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Finalized: Work in progress. Last Update: Leitz 30mm f/4.5 Milar Macro Manufacturer: Ernst Leitz, Wetzlar Manufacturer's lens designation: Milar f=30mm 1:4.5 Currently manufactured: No Lens type: Macro Lens, Aristophot System Focal length: 30mm Aperture range: 2/6/12 (=reduction rate?), No click stops, Manual, 10 blades Design: TBD Flange Focus distance: - Recommended magnification range: TBD. Optimal magnification: TBD Mount: RMS, Microscope thread Sensor format/coverage: up to 90mm x 120mm, or more Front filter: No Lens coating: No Introduction year: pre 1940? S/N of test object: 25246 Working distance graphs: Image of test object: Transmittance SummaryDefinitions of the parameters below Range: The Milar f=30mm f:4.5 lens transmits 1-78% in an increasing slope from 308nm to 400nm. TVISmax (%) = 87% T400nm (%) = 78% T365nm (%) = 69% This high percentage is an indicator for relatively short exposure time under typical UV-pass filtration peaking around 365 nm. λUV HMvis(nm) = 336nm λUV HM400 (nm) = 334nm λUV Zero (nm) = 308nm These three values indicate that the lens is working well for upper UV-B photography with some filters and a few for this, suitable cameras. Spectral transmission graphs:UV-NIR, Milar 30mm 1:4.5 The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, Milar 30mm 1:4.5 UV-Log, Milar 30mm 1:4.5 Numerical Spectra Data available: Yes General comments about the UV-reach: TBD Filters and how to use them on this lens:It is only to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. Handling and focussing:This lens needs to be combined with a helicoid or macro bellows to set desired magnification. The original Aristophot System was big using long extensions. The possible magnification useable is limited by how you can illuminate the motif, if the lens is used for reflected light photography Flare: TBD Sharpness: TBD Lens distortion: TBD Chromatic Aberration / fringing in UV: TBD Image samples:UV: image Filter: UV, Fringing: image Filter: UV, Fringing 100%: image Filter: VIS+NIR: image Filter: NIR: image Filter: long pass 800nm

Finalized: Work in progress. Last Update: Novoflex 60mm f/4.0 Macro-Noflexar Manufacturer: Staeble-Werk? Manufacturer's lens designation: NOVOFLEX-MACRO-NOFLEXAR, Currently manufactured: No Lens type: Macro Lens, for slide copy Focal length: 60mm Aperture range: 4.0 - 16, Manual, 10 blades Design: TBD Flange Focus distance: - Recommended magnification range: 0.6x - 2x ( from the 60/4.5 - version ) Optimal magnification: TBD Mount: M39 x 1 Sensor format/coverage: TBD Front filter: 40.5 x 0.75 Lens coating: Yes Introduction year: after 1969 S/N of test object: 336844 notes: Earlier versions with the same lens speed were marked (NOVOFLEX) STAEBLE-KATAGON and BALFLEX on the rear end surface Even earlier versions had a lower speed of f/4.5 Image of the test object: Transmittance SummaryDefinitions of the parameters below Range: The Macro-Noflexar 60mm f/4.0 lens transmits 1-80% in an increasing slope from 328nm to 400nm. TVISmax (%) = 91% T400nm (%) = 82% T365nm (%) = 72% This high percentage is an indicator for relatively short exposure time under typical UV-pass filtration peaking around 365 nm. λUV HMvis(nm) = 346nm λUV HM400 (nm) = 344nm λUV Zero (nm) = 328nm These three values indicate that the lens is working well for mos UV-A photography with filters and for this, suitable cameras. Spectral transmission graphs:UV-NIR, The Macro-Noflexar 60mm f/4.0 The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, The Macro-Noflexar 60mm f/4.0 UV-Log, The Macro-Noflexar 60mm f/4.0 Numerical Spectra Data available: Yes General comments about the UV-reach: TBD Filters and how to use them on this lens:It is possible to use front and also rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. Handling and focussing:This lens needs to be combined with a helicoid or macro bellows to set desired magnification. Sharpness: High Image samples:UV: Stacked from 4 images, imaging scale ca 1.5:1, 100% Image crop Filter: S8612, 2mm + U-360, 2mm BUG-3: Stacked from 4 images, imaging scale ca 1.5:1, 100% Image crop Filter: S8612, 2mm + BG3, 2mm BUG Stacked from 4 images, imaging scale ca 1.5:1, Image crop Filter: S8612, 2mm + UG5, 1.5mm

I saw that there was a Leitz Focotar-II 100mm f/4.5 for sale at eBay. https://www.ebay.com/itm/285810363319 The price is reasonable for such a good and also rare lens. I think I paid a bit more for my copies. An enlarger lens much better suited for UV is the Focotar-2 50mm f/4.5 Several other versions of 50mm Focotars are almost as good, but a few types are not that suitable for UV. If anyone is tempted to get a 50mm Focotar, please check my evaluations here: https://www.ultravioletphotography.com/content/index.php?/forum/639-uv-lenses-non-helicoidal/ The 100mm Focotar-II is a rather rare lens, produced in small batches, totally maybe 2000pcs, if I remember correctly. Adapted with a suitable helicoid it is a very sharp lens for general photography and especially for close-ups. It is usable for UV to some extent as the shortest wavelength cutoff is rather deep. However the slope of decaying transmission is unusually gradual starting rather early, close to VIS. There has been a rumor that this lens was excellent for UV, so I have bought and tried two copies of them, with different production dates, as I suspected differences over production-time. I returned the first one, that I found lacking for UV, but kept the second as it is such a nice lens for VIS. The second one I got, had a serial number very close to the one copy owned by one of our members, that believed it had a good deep UV-transmission as he got reasonably good images when using the lens.

Those fortunate enough to own or use a Coastal APO 60 mm f/4 lens know this is a superb performer in nearly all areas. On its own the lens focuses to 1:1.5 (so is not quite 'macro') and it is virtually parfocal over the entire spectral range 300 to 1100 mm. The sharpness is mind-boggling and the clarity of its colour rendition has to be seen to be believed. So, what's the caveat? It has been known for a while that this lens produces a strong hot spot when focused close. I believe NG member Andrea G.Blum was the first user to report this issue. I was quite puzzled at her findings, since my initial testing hadn't shown this issue, but I was able to corroborate them later. It turned out I had largely avoided the hot spots by using added extension to get beyond 1:3 instead of using the built-in helicoid mechanism and had not stopped down beyond f/8-11, both of which measures mitigate the issue to some extent (according to Dr. Brian Caldwell, the optical designer). A little later I moved the Coastal lens onto my broad-band modified Panasonic GH-2 cameras and largely forgot about the hot spot issue as it by some magic apparently had disappeared. The reasons for that will be clear later. Once in a while, when the lens saw use on some of my Nikons, the issue resurfaced though. So the magic had its limitations. Fellow UV shooter Enrico Savazzi posted an interesting article http://savazzi.freeh...60_hotspot.html that indicated the hot spot issue could be tamed by using a specially crafted lens hood on the Coastal lens. He verified that the hot spots had gone on his Panasonic camera, but could not tell if the same solution would work on a larger sensor format. Now, this intrigued me as I rarely if ever encountered the hot spot problem on my own GH-2 camera and I hadn't done anything special as far as I could recall. Why was that? This is one of my work-horse Panasonic GH-2 cameras with the standard setup for UV. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-74985600-1376729737.jpg To protect against the dangers of field work (rain etc) the lens had an improvised shade consisting of K-4 + K-5 rings. The Baader U2" filter is inside the lens mount adapter. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-00019400-1376729888.jpg So, could this explain why no hot spots were observed at all? Let us return to the Nikons. Here is another work-horse, a broad-band D600 with the Coastal lens attached. The Baader U2" sits in a step ring on the front. This setup does indeed produce a strong hot spot. On the Nikons I cannot use rear-mounted filters unless I aim for higher magnification using a bellows device or a focusing helicoid. So the filter(s) usually go to the front of the lens. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-51693200-1376730176.jpg Thus we need to add some kind of shading to the lens. As the Baader U2" has the unusual and (to photographers) awkward 48 mm thread, the filter needs to be inserted in some kind of retainer. I use a K-4 ring and a small gasket to make the filter sit tight inside the K-4. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-39707300-1376730464.jpg However, something has to be put in front to prevent the filter from dropping out. Another K-4 ring could be used. but for now I used a spare lens hood for the Voigtländer 90 mm f/3.5 SL.2 lens. Anything in terms of step rings could be used, starting with 52 mm threads and ending with a clear aperture of approx. 40 mm (so, for example, 37.5 or 39 or 40.5 mm to 52 mm would do But the Voigtländer item was next to me on the work table). http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-48962900-1376731418.jpg Add this to the K-4 retaining the Baader filter, and the hot spot issue now vanishes for good. The basic configuration will not vignette towards infinity. If a better shading is required, add another K-4 or a K-5 or the small 39 mm ring for the Voigtländer. Be warned you now have vignetting before you reach 1:3. So remove the additional ring(s) for medium- to long-distance work and you'll be just fine, no vignetting occurs. This is the final setup for the Nikons. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-33870500-1376730920.jpg Now we are in a position to understand why the Panasonics behaved differently. Firstly, the filter pack was by default shaded as it was in the rear not in the front, and secondly, the K-rings I added as a makeshift lens hood prevented off-axis stray light into the lens. For the same proactive measures to work on the Nikons with their larger sensor formats, you need a conical lens hood with a clear opening slightly larger than the front element of the lens. If the makeshift hood was removed from the Coastal when it was attached to a Panasonic, the hot spot reappears. This clearly indicates the underlying issue is inside the lens assembly and is not per se caused by the filter. Perhaps an edge of an optical cell is insufficiently coated or some reflective surfaces inside the casing remain. We are reminded that an optical design, no matter how good, ultimately is limited by the physical structure it is placed into. I have tested these setup (Panasonic and Nikon D3200/D600) and even at f/45 there no longer is any hot spot. Without any hood (D600) a strong hot spot is obvious. It starts to manifest itself from f/8 onwards and here at f/45 is pretty prominent. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-74253700-1376732081.jpg Now, without altering anything of the set up otherwise, add the lens hood. Poof - no more hot spot. Contrast is improved so all the dust on the filter is clearly visible. http://fotozones.com/live/uploads/monthly_08_2013/post-15-0-86014500-1376732115.jpg By the way, the Coastal 60 APO is amazingly sharp even at f/45. [Also posted on fotozones.com http://fotozones.com...-apo-60-mm-f4/]

Just to be clear - this is about the 135mm lens, not the 35mm. A couple of years ago I got a Prinz Galaxy 135mm f/3.5 lens for some reason. The aperture wasn't working properly, so I got my money back but the seller didn't want it returned as it was only a cheap item. I found it at the back of a drawer yesterday, and partially dismantled it and managed to fix the problem. So I thought I'd try it in UV - which was probably why it was bought in the first place. There are several versions of this lens, and an f/2.8 model. This is what the tested lens (with a T2-EOS adapter) looks like: The same lens appears under other brand names, inc. Hanimar (Hanimex). It has a typical solid, all-metal construction of lenses from the 1970s. UV Reach I checked the UV reach by comparing exposures through 380BP20, 345BP25, and 315BP20 filters and comparing filter factors normalised to 1 for the 380BP20. Here is a comparison against the UV-friendly Focotar-2 and the Yongnuo/Canon 50mm lenses compared in another recent post. The lower the filter factor, the better the lens transmission at that wavelength range. The Prinz Galaxy is remarkably good at 345nm - far better than the 50mm lenses. But, like the 50mm lenses, it can't produce an image at 315nm. This good performance at the upper part of the UVA range means it is probably OK for general purpose broadband filters like the Baader U. Baader U The following images compare the Prinz Galaxy with the Focotar 2 when using a Baader U filter. Images have been cropped so that they show approximately the same area. In all cases, the Focotar-2 images are shown first. The left image has been WB-ed using PTFE, and the right image is with increased saturation. A couple of things to note about the Prinz Galaxy: It was possible to WB against PTFE in the usual way - I was unable to do this when I tested the 50mm lenses. Surprisingly the Prinz Galaxy is showing more yellow (representing the area around 350nm) than the Focotar-2, which has a much deeper UV reach. This is evident in the second image, and you can see it on the full resolution version of image 3 around the figure's heir and lapels. I'm not sure what's happening here. Image Quality These images compare the Prinz Galaxy against the Focotar-2 when using a Baader U filter. The Prinz Galaxy appears to perform better at the corners at f/3.5 than at f/8! Obviously not what you'd expect. Initially I assumed a mistake, but a repeat of the exercise gave the same results.

Finalized: Work in progress. Last Update: Nikon 80mm f/5.6 EL-Nikkor: Nippon Kogaku Japan Manufacturer: Nikon Manufacturer's lens designation: EL-NIKKOR 80mm f/5.6 Nippon Kogaku Japan Currently manufactured: No Lens type: Enlarger lens for film up to 56mm x 72mm ( Ø100mm ) Focal length: 80mm Aperture range: f/5.6 – f/45, Manual, 8 blades Design: 6 elements in 4 groups Flange Focus distance: 70mm Recommended magnification range*: 0.067x – 0.5x. Optimal magnification *: 0.2x Mount: M39 x 26tpi thread + hidden 32.5 x 0.5mm thread behind a built in step ring. Sensor format/coverage: up to 56mm x 72mm ( Ø100mm ) at 0.2 x magnification Front filter: 34.5 mm x 0.5 mm Introduction year: pre 1960? S/N of test object: 805773 * Definitions reversed from normal enlarger definition, referring to the motif not the negative-plane Lens review (VIS), on the web: Lens Manual on the web: http://www.savazzi.n...El-Nikkor_2.pdf Image of test object: Transmittance SummaryDefinitions of the parameters below Range: The EL-NIKKOR Nippon Kogaku lens transmits 0-70% in an increasing slope from 315nm to 400nm. TVISmax (%) = 88% T400nm (%) = 84% T365nm (%) = 67% This high percentage is an indicator for relatively short exposure time under typical UV-pass filtration peaking around 365 nm. λUV HMvis(nm) = 349nm λUV HM400 (nm) = 348nm λUV Zero (nm) = 316nm These three values indicate that the lens is UV-capable into the upper UV-B range under appropriate filtration. Spectral transmission graphs:UV-NIR, EL-NIKKOR 80mm f/5.6, Nippon Kogaku Japan The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, EL-NIKKOR 80mm f/5.6, Nippon Kogaku Japan UV-Log, EL-NIKKOR 80mm f/5.6, Nippon Kogaku Japan Numerical Spectra Data available: Yes General comments about the UV-reach: ffff Filters and how to use them on this lens:The front filter thread is rather odd, but suitable adapter can be found at RafCamera: https://www.ebay.com...amera?_bkw=34.5 It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear element mount ring. The rear lens element is recessed and thus safe and the ring provides a good reference plane for orienting the filter normal to the optic axis. My Omega 330W80 Improved Ø25mm, is mounted in a 27mm-filter ring and works well to mount as it is. Handling and focussing:This lens needs to be combined with a helicoid or macro bellows to set desired magnification. With short enough minimum length of those it is easy to obtain focus at infinity even for DSLRs with long back-focus distance. https://www.ultravio...__fromsearch__1 Flare and sun-stars: TBD Sharpness: I have found the lens impressing sharp. My main usage has been for closeup UV and UV+VIS photography. Lens distortion: The lens Chromatic Aberration / fringing in UV: C Image samples:UV: image Filter: UV, Fringing: image Filter: UV, Fringing 100%: image Filter: VIS+NIR: image Filter: NIR: image Filter: long pass 800nm

In a previous topic I asked for some advice on softwares to simulate/design lenses, and I ended up using Winlens 3D by Qioptiq (the free version), which was suggested me by rfcurry. You can watch a tutorial on YouTube to learn how to use it, and it is pretty simple to use. I was able to simulate commercially available lenses as well as designing my own. All lenses shown here were simulated/optimized for infinite conjugate (object at infinity, in my case either at -infinity or - 1 km). Lenses usually perform differently when focuses at infinity or close up. Basics Here you can see some examples of common lens aberrations (and why a single element, especially if it has spherical surfaces, will make soft images). This is a simple fused silica plano-convex lens (Thorlabs LA4052), with the aperture 1 mm behind the lens and set at f/1.4: You can clearly see spherical aberration. The external rays are focused closer than the central ray, which will make the image soft. Stopping down to f/4 greatly reduces the aberration: Also, longer focal length lenses generally suffer less from this problem because if the lens' diameter is kept constant, the aperture is narrower (higher f-number). Below Thorlabs LA4380 at f/5: Off-axis rays may not be focused to a point, and often they are focused closer to the lens (Petzval field curvature). Also, they may suffer from coma (another type of aberration). The same lens, with off-axis rays: Magnification: Achromatic lenses The refractive index of all materials is not constant with wavelength, but changes slightly (it usually increases for decreasing wavelengths). This means that a lens will split colors exactly how a prism would (in fact lenses can be modelled as a stack of prisms), showing chromatic aberration. To partially solve this, two different types of glass are used, a low index low dispersion crown glass and a high index high dispersion flint glass, so that the chromatic aberrations of the two lenses cancel out, focusing two wavelengths (usually blue and red) in the same plane. This can be done in UV, usually using fused silica as "flint" and CaF2 as "crown". Andy is interested in Thorlabs UV achromatic doublets, so I decided to simulate them. The shortest one they offer has a focal length of 100 mm (Thorlabs ACA254-100-UV). Here I simulated it at f/5. I used a diameter of 25.4 mm (one inch) which is more than the clear aperture of this lens (18 mm). The horizontal beam is nicely focused to a point with very little spherical aberration, while the off-axis beams are not as good. Things improve at f/11: Since this is an achromatic lens, I tested its chromatic aberration, and for the UV range I got this (blue: 254 nm, green: 313 nm, red: 365 nm): Apart from a small area near 200 nm, every UV wavelength is focused to a different spot, which surprised me. This is a wider view (300-1100 nm): This lens will focus UV and SWIR in the same spot. The weird UV graph is confirmed by Thorlabs: The longer versions of this lens behave as expected. This is the focus shift for the 150 mm version, between 300 and 500 nm: Edmund Optics sells UV-to-NIR corrected triplets. This is the 90 mm version, at f/5, showing some field curvature: ...and at f/8: Chromatic aberration (200-1100 nm): Custom lenses Using two Thorlabs ACA254-100-UV lenses, I made a 63 mm lens with good performance. The distance between the doublets is 9 mm measured from the centers (middle). The aperture is in the middle. Lens at f/3.5: Chromatic aberration (300-1100 nm): Next, a 142 mm f/7 lens made only with custom elements: Lens at f/7: Chromatic aberration (300-1100 nm): And lastly, a 46 mm f/2 Cooke triplet made only with fused silica elements (no chromatic aberration correction). f/2: Magnification of the on-axis spot: f/2.8: f/4: Left element: Thorlabs LA4148, middle element: Thorlabs LD4735, right element: Thorlabs LB4096. Distances (measured between the lens surfaces, in the middle of the lenses): left-middle: 5 mm middle-right: 16 mm aperture 12 mm behind the rightmost surface of the right lens (the exact placing is not strictly important, it could very well be between the middle element and the right element, which it almost is).

A friend has suggested that the Voïgtlander Nokton 25mm f0.95 in m4/3 mount is a good UV lens ?

I did a few series oftest shots to compare my ZWB1, 8mm with my U-340, 4 + 4mm - stack to see if my 8mm filter was flawed. Both filter sets were OK in that respect. However I was disturbed by the difficulty of WB those shots. my camera is a full spectrum modified Sony A7III where both dust-shaker and BG-glass has been removed. Jonathan (JMC) has earlier showed that the sensor's protective window do mot give this camera a very deep UV-reach, making it usable for exploring UV-B. So far this has not given me any problems as I am not into such more extreme UV-photography. It works quite well for UV-images including the false-yellow colour band. For the filter test above I used my EL-Nikkor 80mm lens that is one of the better accidental UV-capable lenses. The UV-reach of this lens is normally greater than needed and many lenses with less reach work well too. As I had problems doing a proper WB I decided to redo the test with a lens that has a really good UV-reach down to 200nm. I tested with my 70mm fused silica PCX-assembly and found that lens gave images that was easy to WB in a normal way. My FS PCX lens element is uncoated and has a transmission similar to the graph under the "Graphs"-tab on this page: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=123 Here are some images selected from my tests. they are jut screen shots from FastRawViewer after WB at the roof surface in the foreground. ZWB1, 8mm on EL-Nikkor 80mm old metal type ZWB1, 8mm on PCX FS 70mm assembly ZWB1, 8mm on PCX FS 70mm assembly, 100% detail:

Last Update: 03 April 2021 agb/label/spacing Finalized: Work in progress. Canon 40mm f/2.8 EF STM Manufacturer: Canon Lens Label: CANON LENS EF 40mm 1:2.8 STM Currently manufactured: No Lens type: Auto focus, Prime, Wide Angle, Pancake lens Design: 6 elements in 4 groups Focal length: 40mm Aperture range: f/2.8 – f/22, electronic control only, 7 blades circular aperture Magnification range: to 0.18x at 0.3m. Sensor format/coverage: up to 24 mm x 36 mm Mount: Canon EF Flange Focus distance: EF-standard, 44.00mm Front filter: 52 mm x 0.75 mm Introduction year: between 2012 S/N of test object: 3261100252 Lens review (VIS), on the web: https://www.kenrockw...0mm-stm.htm#rex Lens info on the web: https://global.canon...duct/ef419.html Image of test object: Transmittance Summary Definitions of the parameters below Range: The Canon EF 40/2.8 STM lens transmits 1-84% in an increasing slope from 347nm to 400nm. TVISmax (%) = 94% T400nm (%) = 84% T365nm (%) = 40% λUV HMvis(nm) = 368nm λUV HM400(nm) = 366nm λUV Zero(nm) = 347nm These three values indicate that the lens is only working for some upper UV-A photography. Spectral Transmission Graphs UV-NIR, Canon EF 40/2.8 STM The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, Canon EF 40/2.8 STM UV-Log, Canon EF 40/2.8 STM Numerical Spectra Data available: Yes General comments about the UV-reach: tba Filters and how to use them on this lens: NOTE: The filter threads are plastic. So you must be very careful when mounting filters. A large filter stack may stress the filter threads. The front filter thread is 52mm standard filter thread. It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear surface, that provides a good reference plane for orienting the filter normal to the optic axis. The rear lens element is not recessed and thus needs a filter mounted in a filter ring to place the filter's glass surface at a safe distance from the rear lens element. Handling and focussing: Must be assisted electronically by the camera. Only possible on Canon cameras or with suitable active lens adapters. Autofocus in UV might work with enough light present. TBD Flare and sun-stars: TBD Sharpness: High according to net reviews. For UV ? Lens distortion: TBD Chromatic Aberration in UV: TBD Image samples:

Finalized: Work in progress. Last Update: Steinheil München 50mm f/2.8 Cassar S Manufacturer: Steinheil München Manufacturer's lens designation: Steinheil München Cassar S 1:2.8 f=50mm Currently manufactured: No Lens type: Manual focus, Prime, Normal Focal length: 50mm Aperture range: f/2.8 – f/16, Manual, 10 blades, no click stops Design: 3 elements in 3 groups Flange Focus distance: Mount dependable Mount: M42 x 1.0**, EXA, Also as a fixed mounted lens on several cameras Sensor format/coverage: up to 24mm x 36mm Front filter: 40.5 mm x 0.75 mm Introduction year: early 1950? S/N of test object: 2020691 **Mount of test object Lens review (VIS), on the web: Image of test object: Transmittance SummaryDefinitions of the parameters below Range: The Cassar S 1:2.8 f=50mm lens transmits 0-74% in an increasing slope from 309nm to 400nm. TVISmax (%) = 90% T400nm (%) = 74% T365nm (%) = 68% This moderate to high percentage is an indicator for a short exposure time under typical UV-pass filtration peaking around 365 nm. λUV HMvis(nm) = 337nm λUV HM400 (nm) = 331nm λUV Zero (nm) = 309nm These three values indicate that the lens is working well for UV-B photography with some filters and a few for this, suitable cameras. Spectral transmission graphs:UV-NIR, Cassar S 1:2.8 f=50mm The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, Cassar S 1:2.8 f=50mm UV-Log, Cassar S 1:2.8 f=50mm Numerical Spectra Data available: Pending Filters and how to use them on this lens:The front filter thread is 40.5mm standard filter thread. A step-up filter ring might be needed. It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear flat parts. The rear lens element is recessed and thus safe and the ring provides a good reference plane for orienting the filter normal to the optic axis. My Omega 330W80 Improved Ø25mm, is mounted in a 27mm-filter ring and would work well to mount as it is. Handling and focussing:This lens has a focusing helicoid that smoothly turns almost a full turn for focus at infinity to around 1m. To focus closer external bellows, focusing helicoids or extension rings are needed. Then image quality might improve by reverse mounting the lens. Flare and sun-stars: TBD Sharpness: The lens has a rather curved focus plane and on a full frame sensor the corners are quite soft even when stopped down. Lens distortion: TBD Chromatic Aberration / fringing in UV: TBD Image samples:

Last Update: 03 April 2021 agb/label Finalized: Work in progress. Kuribayashi 105mm f/3.5 K.C. Petri Orrikkor Manufacturer: Kyoei Kogaku Lens front ring label: Kuribayashi K.C. Petri Orrikkor 1:3.5 f=105mm No.<serial number> Introduction year: 1959 Currently manufactured: No Lens type: manual focus, prime, short telephoto Design: 3 elements in 3 groups Focal length: 105mm Aperture range: f/3.5 – f/22, 16 blades, manual preset Magnification range: tbd. Closest focus 1.2m. Sensor format/coverage: up to 24 mm x 36 mm Mount: M42 x 1 Flange Focus distance: M42: 45.46 mm Front filter: 46 mm x 0.75 mm S/N of test object: 35888 https://w.atwiki.jp/...i/pages/75.html Image of test object: Transmittance Summary Definitions of the parameters below Range: The Kuribayashi 105mm f/3.5 K.C. Petri Orrikkor - lens transmits 1-89% in an increasing slope from 330nm to 400nm. TVISmax (%) = 90% T400nm (%) = 89% T365nm (%) = 75% λUV HMvis(nm) = 346 nm λUV HM400(nm) = 345 nm λUV Zero(nm) = 318 nm These three values indicate that the lens is working for UV-A and some UV-B photography. The rather high transmission at 365nm gives comparably short exposure times for a typical UV-pass filter-stack or a Baader U. Spectral Transmission Graphs UV-NIR, Kuribayashi 105mm f/3.5 K.C. Petri Orrikkor The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, Kuribayashi 105mm f/3.5 K.C. Petri Orrikkor UV-Log, Kuribayashi 105mm f/3.5 K.C. Petri Orrikkor General comments about the UV-reach: The lens do reach quite deep into UV for a 105mm lens. This reach will be enough for most UV-photography, with sun or UV-converted flash as light source, together with a typical UV-pass filter-stack or a Baader U. Filters and how to use them on this lens:The front filter thread is 46mm standard filter thread. It is also possible to use rear mounted filters, in lens mount adapters, or placed directly in the camera. Handling and focussing:Due to the long 45.46mm flange focus distance this lens will be possible to mount with lens mount adapters and focus at infinity with most DSLRs. Sharpness: TBD Lens distortion: TBD Chromatic Aberration in UV: TBD Image samples:

If f/2.8 is not fast enough for you, here's an f/2 lens. The focal length is about 47 mm. The lens is not yet optimized for "buildability". Also, the distance from the rear element to the sensor required for infinity focus is less than that of lens #2. Mounting a helicoid would be more difficult. The lens does not correct for chromatic aberration. Lens simulated using WinLens3D Basic. Simulated at 340 nm. The lens has some barrel distorsion and vignetting at wide apertures. I will post more detailed information when I will optimize the lens for buildability.

Lenses used in this test: Aldis 120/7.7 Uno Anastigmat Bausch & Lomb 180/8.0 Rapid Rectilinear Canon 200/2.8L EF EL-Nikkor 80/5.6 (metal version, enlarger) EL-Nikkor 105/5.6 (metal version, enlarger) Ensign 75/4.5 Ensar Anastigmat Leitz Wetzlar 50/4.5 Focotar-2 (enlarger) Meyer Optic Görlitz 50/2.9 Trioplan Prinz Galaxy 135/3.5 Steinheil München 50/2.8 Cassar S Voigtländer 105/6.3 Voigtar Anastigmat Zeiss Ikon 75/4.5 Nettar Zeiss Ikon 50/4.5 Novar Virtually all of the UV-friendly lenses we use date back to the 1950s-1970s and typically have M42, M39, or Exakta mounts. But how about lenses that are older than that, from the days before AR coatings and interchangeable mounts – how good might they be for UV? As a lockdown project I acquired some of these older lenses to try them out in UV (and also in IR). The criteria for the choice of lenses was: Made pre-Second World War, and preferably much earlier. Although plenty of pre-First World War lenses are available they are generally of long focal lengths (up to 180mm) because of the large format films in use. You have to go to the 1930s to find 75mm lenses, and wait to the late 1930s (when 35mm and 16-on-127 cameras become more common) for 50mm lenses. Multi-element lenses On or from folding cameras, to make lens removal and adaptation to M42 easy. Maximum price of £20 (inc. any camera still attached to them) – so no Leitz or even Tessar lenses. A working T function on the integrated shutters A working aperture These were the lenses tested: A couple of observations: The Bausch and Lomb Rapid Rectilinear had apertures marked from 4 to 128. It turns out these markings used the U.S. scale (U.S. = Universal Standard rather than a reference to former British colony). U.S. 4 is equivalent to f/8. The Meyer Trioplan 50mm f/2.9 illustrates why I sometimes find it hard to understand the modern world. It is a mid-range 1930s triplet and yet the early post-WW2 copies in M42 or Exakta mounts demand ridiculous prices of £150-300 (a new Canon 50mm f/1.8 costs just £130). The only thing the Trioplan has going for it is its “distinctive soap bubble bokeh” when used fully open. So if you want a lens that gives you so-so mages with an annoying, distracting background then this is the lens for you. More amazing still is that Meyer Optik Gorlitz is back in business making their range of 1930s lenses – a previous crowd-funded incarnation offering the Trioplan at $2,000 failed a couple of years ago, and the current owners are selling Trioplans and the other 1930s models at a mere $1,000. I think some people just have too much money UV Transmission The transmission of the lenses through my three UV bandpass filters (380BP20, 345BP25, 315BP20) were compared with the metal El Nikkor 80mm. The El Nik was chosen as the benchmark because it is perfectly usable with the 315BP20, whereas benchmarking against the best transmitters (Focotar-2, Cassar S) would have set the bar unfairly high. It turns out that all of these lenses perform at least adequately at 345nm, and so would work well with general-purpose filters like the Baader U. The Voigtar and Trioplan lenses showed good UV reach down to at least 320nm (the peak transmission of the 315BP20), and the Ensar could be used at a push. These are all air-spaced triplets. Unsurprisingly, the lenses with cemented elements (Rapid Rectilinear, Aldis Uno) performed poorly – too poorly to be used at 320nm. But surprisingly the two worst transmitters at 320nm were air-spaced triplets – the Zeiss Ikon Nettar and Novar. Obviously at least one of the elements is made of a UV-absorbing glass. Fluorescence of the lens seems to be the best predictor of UV transmission – it looks like the rear elements of these lenses is the culprit. Resolution The table below compares resolution provided by these lenses in UV, Vis., and IR, and compares them with some other lenses to provide context. In visible light (at f/8 or f/11), the Rapid Rectilinear and Ensar performed very badly. The other lenses hold their own. (I’m sure the poor number for the Trioplan in the centre at f/8 is some kind of an error on my part.) In UV (at f/8 or f/11), the Rapid Rectilinear again performs very poorly. The Aldis Uno is somewhat weak. The Trioplan and Ensar are OK at the centre, but drop off badly towards the corners. The Novar, Nettar, and Voigtar perform reasonable well. In IR (at f/8 or f/11), the Rapid Rectilinear completes its lamentable performance. The Trioplan and Ensar are again let down by poor performance at the edges. The other lenses perform adequately. The characteristics of the Trioplan are similar to those of the Cassar S. Other Aberrations The lenses are clear of pincushion and barrel distortion. Astigmatism is also almost completely absent (as it should be as they all claim to be anastigmats). But there is a significant amount of chromatic aberration – especially in the Rapid Rectilinear, Ensar, and Nettar.

A triplet lens that comes attached to the soviet Smena 8M rangefinder that I've routinely seen go for 2€ on local flea markets. As is obvious from the name, it has the focal length of 40mm and a dark maximum aperture of f/4. The in built aperture goes all the way up to f/16 and has 8 blades. The lens seems to have a 35mm filter thread, I haven't messured it precisely though. Only disadvantage I can already see is that the tiny ring around the front element controls the aperture, so if a filter is mounted, it is impossible to adjust aperture. The elements seem to have a single coating. To test the UV performance, I mounted the notoriously UV capable Soligor 35mm f/3.5 on my camera with a stack of QB39+ZWB1. I pointed the lens at the sky, color balanced on the sky as well to exaggerate the tint. There is barely any. I would do a pinhole test or such but I don't own bleeding edge filters like the Baader U or other trusty formulas, I also don't have any UV lenses to compare this to. I might try it if I make a pinhole though, unless anyone here is quicker. Here's a review of the image quality this lens provides in the visible, it's not amazing but the major downfall seems to be field curvature, which means that shouldn't be much of an issue for closeups, it gets better stopped down too. https://radojuva.com/en/2017/08/lomo-t-43-40-4/ For anyone out there with a good filtering solution and a mirrorless camera, this could be an interesting option.

I recently had to put an order in with Thorlabs and while I was there, I thought I'd try out another one of their lenses for UV photography - a 79mm UV fused silica aspheric (https://www.thorlabs.com/thorproduct.cfm?partnumber=ASL10142M). In the past I've played around with some of their 40mm lenses in a setup built from their parts, but I got a lot of distortion at the image edge with that (not a big surprise). See here for the thread on that - https://www.ultravioletphotography.com/content/index.php/topic/3754-back-to-basics-40mm-singlet-lens-from-thorlabs/page__view__findpost__p__33674 Moving to a longer focal length and an aspheric lens design, I hoped would help get some of the distortions under control and make the lens more usable. Here's the lens. And mounted on the camera using a range of parts. The weather here is dull and rainy today, but I went out and tried to get a photo anyway, taking a Nemo UV torch with me to boost the 365nm UV a bit. Baader U filter used and whitebalanced in Darktable. This the full frame image from the A7III, just with some denoising and contrast boosting done, with the lens stopped down about half way (I guess about f8). Resized for sharing obviously. And a crop from the original, kept at the original image resolution. The Buttercup photo was done at ISO6400 and 1/15s with a mix of daylight (no sun) and Nemo 365nm UV torch. Overall, I'm quite impressed with this little singlet. I'll hopefully do more with it when the sun comes out, but I also want to try it for UVB (or even UVC) imaging.

Finished: 04 Jan 2021 Last Update: Sunex 5.6mm f/5.6 185° SuperFisheye Manufacturer: Sunex, Inc., 5963 La Place Court, Suite #309, Carlsbad, CA 92008 Manufacturer's lens designation: Sunex, 185° SuperFisheye 5.6mm F/5.6 Note that Sunex includes defishing software with new purchase of this lens. Introduction year: 2008? Currently manufactured: Yes Lens type: Fixed focus, Circular fisheye Focal length: 5.6mm Aperture range: f/5.6, fixed, circular Intended Focus range: 0.5m - Infinity, fixed. Sensor format/coverage: APS-C, image circle 14.5mm. Available mounts: Canon EF, Nikon F, other via adapters. Front filter: None S/N of test object: C-2L05AG219 Lens review (VIS), on the web: https://www.kenrockw...per-fisheye.htm Transmittance SummaryDefinitions of the parameters below UV Range: The Sunex lens transmits 0-65% in an increasing slope between 345-400nm. TVISmax (%) = 85% T400nm (%) = 64% T365nm (%) = 16% This low percentage is an indicator for a longer exposure time under typical UV-pass filtration peaking around 365 nm. λUV HMvis(nm) = 382nm λUV HM400 (nm) = 375nm λUV Zero (nm) = 350nm These three values indicate that the lens is best in the near-UVA range. Spectral transmission graphs The transmission measurement accuracy into the NIR range is less good due to limitations in the light source and spectrometer configuration. UV-NIR, Sunex, 185° SuperFisheye 5.6mm F/5.6 UV, Sunex, 185° SuperFisheye 5.6mm F/5.6 UV Log, Sunex, 185° SuperFisheye 5.6mm F/5.6 Numerical Spectra Data available: Pending General comments about the UV-reach:Wide angle lenses from 28mm and shorter normally have a poor UV-transmission. They also give problems with filters and filter stacks due to vignetting and in some cases flare and colour shift at the corners when using dichroic filters. Wide angle lenses normally do not need a very deep cutoff for the typical usage in landscape photography as sunlight contains little UV below 330nm. Even some transmission closer to 400nm might be enough for that. For such a wide lens as the Sunex the transmission is unusually good and still useable, after a proper white-balancing. Filters and how to use them on this lens: Fisheye lenses cannot be used with front-mounted filters and this lens has no holder for rear mounted gelatin-type filters. It is possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc., or placed directly in the camera. An alternative, if space in the camera allows, is to putty-mount a filter directly against the lens's rear element mount ring. The rear lens element is recessed and thus safe and the ring provides a good reference plane for orienting the filter normal to the optical axis. Here a filter glass from a B+W 550nm long-pass filter is putty mounted. The rear element's diameter is small enough that it is possible to mount 25mm filters. My Omega 330W80 Improved, used for the UV-image below, is mounted in a 27mm-filter ring and works well to mount as it is. When using rear mounted filters, it is important to realise that they shift the focusing towards infinity as the filter-glass gives a shorter optical path length mimicking a forward shift of the lens. For wide-angle lenses even a short shift is very critical and can destroy sharpness at infinity. The Sunex lens has a factory set critical focus point which can be readjusted. That has to be done if introducing rear mounted filters. The massive lens-block is mated to the lens-mount parts with an external M42 x 1mm thread. The lens-block is then locked with four grub screws placed in its cylindrical side. The screws can be loosened with a 1.5mm hexagonal (Allen) screwdriver or bit. When these screws are loosened, the lens-block can be rotated in the mount and thus shifted back and forth to set a proper sharp infinity. When using different filters, there is an optimal setting for each filter so it is convenient to make a scale to quickly set the proper focus-point when changing filters. Here is my scale for the filters for which I have so far found the settings. Canon EF mount mechanical quirks: The mount does not have any coloured indication dot for guiding the rotation angle when mounting the lens. When mounting the lens by turning it correctly, it distinctively clicks into place at the end point as any normal lens. The mount also lacks the feature that normally stops the reverse rotation beyond the engage/release-point when removing the lens from the camera. These are not big problems when you get used to them, but at first they can cause confusion. Aside from these quirks, the mount is made with a very good precision. Handling and focusing: As the aperture is fixed, then either Aperture priority or manual mode is the only way to use the lens. If a scale with focus settings is used, it is easy to reset to infinity focus. If a closer focus is desired, loosening the locking screws and turning the lens to a closer focus is easy. However, then do not expect any flat field as the lens is not being used as intended. The main difficulty when using this lens is to avoid getting your feet or shadow in the picture. You also have to look for different compositions than with a normal lens as everything is shrunk and distorted. This effect is shared with all super-wide-angle lenses. Flare and sun-stars: The lens design and coatings are very good so there are seldom big problems with flare even with the sun in the image. There are no sun-stars as the fixed aperture is circular. Sharpness: I have found the lens impressively sharp. My main usage has been for IR and VIS+NIR photography. Fisheye projection: The lens deviates a bit from the ideal fisheye projection, pronouncing the central parts and squishing the edges. This can be corrected almost completely by software like Hugin or LensFun by mapping the error and generating correction coefficients. Darktable might be used to make the projection more pleasant by applying the lens-correction for another fisheye lens. I prefer the correction made for Sigma 8mm 3.5 FX for that, but often no processing or correction is needed. Chromatic Aberration / fringing in UV: In extreme situations in UV, the lens has a distinct fringing near the edges of the circle. That can often be more or less cured by software in the postprocess. The second UV sample below shows such a situation with dark beams in silhouette against the UV-rich sky. The third image shows a partial section at 100%. IMAGE SAMPLES Reflected Ultraviolet. Filter: Omega 330W80 Improved UV-Pass Fringing in Reflected UV. Filter: Omega 330W80 Improved UV-Pass. Fringing in Reflected UV at 100%. Filter: Omega 330W80 Improved UV-Pass. Reflected Visible and Near-Infrared. Filter: ZWB3 Dual Bandpass. Reflected Near-Infrared. Filter: 800 nm Longpass. Full Resolution Reflected Near-Infrared. Filter: 800 nm Longpass. Double-click to see the full resolution image. Find the second bird against the sky!

There's not much information I could find on these lenses. As always, I have no affiliation with the seller. https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://wavelength-oe.com/application-notes/uv-lens-detectors/&ved=2ahUKEwjaloHY8JmDAxW1cPEDHXX4DfUQFnoECBkQAQ&usg=AOvVaw1B0AN844MuygAHm6tXEKee https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://wavelength-oe.com/wp-content/uploads/2020/02/UV-Lens-Detectors-Application-Note.pdf&ved=2ahUKEwjaloHY8JmDAxW1cPEDHXX4DfUQFnoECBoQAQ&usg=AOvVaw3fy3QIx9Ur54cGyzp4axIz

Finalized: Work in progress. Last Update: Note: Additional information or links about this lens are welcomed and will be incorporated into the first post as time permits. Carl Zeiss 105mm f/4.3 UV Sonnar Manufacturer: Carl Zeiss / Hasselblad Designation/Label: Carl Zeiss UV-Sonnar 4.3/105 (Serial number) Currently Manufactured: No (?) Lens Type: prime/telephoto Design: 7 elements in 7 groups, sonnar, elements are silica (quartz) and calcium fluoride, probably uncoated Focal Length: 105mm nominal (107.5mm according to product literature) Aperture Range: f/4.3 - f/32, 5 blades Magnification: ? Macro: Not a macro lens, but can be used with extension tubes Working Distance: 1.8m - ∞ Format Coverage: designed for medium format (6x6cm). Negative size 56.5 x 56.5mm according to product literature Mount: Hasselblad V mount Helicoid: Not required Flange Focal Distance (FFD): 74.9 mm Front Filter: B50 or B60 depending on model (C or CF version). Can be adapted to take 52mm filters or others. Introduction Year: ? Serial Number: ? Photos of Lens TBD Transmittance Summary Product data sheet quotes the spectral range for the lens as being 215-700nm, but does not give a transmission curve. Transmission beyond 700nm will take place, however this is likely beyond the range it is designed for in terms of minimizing and refocusing. Spectral Transmission Graph Measured transmission between 280nm and 420nm. As expected based on the design with quartz and calcium fluoride lens elements, transmission between 280nm and 420nm is relatively flat. Photos Made with Lens Original post - https://www.ultravio...dpost__p__23494 Equipment [Canon EOS 7D ACS UV conversion + Zeiss 105mm UV Sonnar + EOS/Hasselblad adapter + EOS 35mm Extension tube, full size and cropped] Ultraviolet Light [f/8 for 1.6s @ISO 400 in Sunlight using ACS in-camera filter] Other example images given here - https://www.ultravio...dpost__p__27482 Additional information The lens has a built in leaf shutter for use on the Hasselblad V mount cameras. Link to the product information brochure: https://www.zeiss.co...ar-43105-en.pdf When advertised for sale, the adverts often say "Super rare, 1 of 73 made". This is not correct. Having spoken with Zeiss, they think around 400 are out there. However their records are not complete. When I contacted them about mine, they discovered it was from a batch that they previously did not have in their digitised records (presumably not all the records have been transfered over from hard copies). Can be adapted for 35mm usage using the relevant Hasselblad V mount adapter. Lens designed for NASA - mentioned in the Apollo 16 equipment inventory (https://history.nasa...photoequip.html). The Apollo 16 image atlas lists 83 UV images here, presumably taken with the 105mm UV Sonnar (https://www.lpi.usra...0mm/mission/?16). Also used at Los Alamos for UV imaging of hydrogen flames (https://permalink.la...t/LA-UR-88-1121). There is adequate space behind the lens for rear mounting a filter if required, especially if being mounted on a 35mm camera or equivalent. Anecdotally, based on my experience, it is not as sharp as the Rayfact 105mm UV lens, but is by no means a soft lens.

STICKY LIST Sticky :: SWIR Photography: Cams, Mods, Lenses, Lights, Links Sticky :: UV-Capable Lenses (You are here.) Sticky :: UV/IR Books Sticky :: UV/Vis/IR Filters Sticky :: UV Induced Visible Fluorescence Sticky :: UV Photography: Cams, Mods, Lights, Links Sticky :: White Balance in UV/IR Photography Best Basic Gear: Goggles, Filters, Torches Beginners might want to start with this topic. Then return here for more details. Sticky :: UV-Capable Lenses by Andrea G. Blum for UltravioletPhotography.com [Last Update :: 13 Nov 2023. Sticky formatting was cleaned up.] This Sticky is presented in separate posts within this topic for easier maintenance. Section 1. You are reading it now. "-) Section 2. UV-Dedicated Lens :: Photography :: Currently Manufactured Section 3. UV-Dedicated Lens :: Photography :: Historical Section 4. UV-Dedicated Lens :: Special Use Section 5. UV-Capable Lenses This section contains a brief summary of our UV LENS TECHNICAL DATA board and a list of possibly good lenses which have not yet been measured. UV LENS TECHNICAL DATA contains a detailed analysis of some of the best lenses for reflected UV photography. This board is produced and directed by our member Ulf Wilhelm. This board is briefly summarized in Section 5 of this topic. Note from Editor: This Sticky began as a joint effort by the members of various forums who enjoy UV/IR photography. Thanks to everyone for their suggestions, comments, proofreading, lists, links, measurements, experiments and all round good fellowship. Please PM Andrea B. on UltravioletPhotography.com with any corrections, additions or suggestions. Or write to rudbeckia ultravioletphotography com. Abbreviations: IR = infrared UV = ultraviolet UVIR = ultraviolet and/or infrared [ultravioletPhotography.com does not endorse any specific products as a website. We simply offer reports, reviews and gear lists for your further investigation. Any opinions in such reports/reviews/lists belong solely to the poster writing them. UltravioletPhotography.com as a website is non-monetized and receives no compensation or income from any source.] UV-Dedicated Lenses There are UV-dedicated, UV-capable lenses and ordinary lenses. A UV-dedicated lens is one which was designed and manufactured specifically for reflected UV photography. One of the most familiar UV-dedicated lenses is the UV-Nikkor 105/4.5. Others are discussed in later sections. Such lenses are very expensive and out-of-reach for most who want to try shooting UV. The next section will discuss the alternative: less expensive, non-UV-dedicated but UV-capable lenses. For the record, here are some characteristics of a UV-dedicated lens suitable for reflected UV photography. Transmittance is high. Transmittance is (usually) an even 60-70% or more across the lens range. Elements are typically made from fluorite and/or quartz for higher transmittance. Other glass is sometimes used. Non-fluorescing elements, element glue and internal lens parts under UV light. Wavelength range is wide. The lens should reach to at least 310-300 nm. Some reach all the way to 200 nm. Lens is corrected for chromatic aberration in the UV range. Although please note that many UV-dedicated industrial lenses - designed for use with narrowband filters - are not corrected. Lens is corrected for focus shift between the Visible and UV wavebands. This would permit focusing in visible light before placing the dark UV-pass filter over the lens. This has become lless important with the advent of Live View and UV-LED torches together which permit focusing directly in UV for many scenes. Again, it must be noted that some UV-dedicated industrial lenses not intended for typical photography are not corrected for UV-Vis focus shift. . UV-Capable Lenses from Birna Rørslett Here at UVP, we term a non-UV-dedicated lens as a UV-capable lens if the following criteria hold. The lens must: Easily disclose well-known UV-signatures. For example, floral signatures of familiar flowers like dandelions and sunflowers should be easily capturable. This first requirement can sometimes be met with an ordinary lens. Have elements, element glue and internal lens parts which are non-fluorescing under UV light. Render subjects with acceptable lack of chromatic aberration in UV. This second requirement is much harder for most ordinary lenses and even for some UV-capable lenses which are uncorrected. Provide sufficient resolution, sharpness and contrast. An ordinary lens which can transmit some UV is useless if it also produces a blurry mess. Require at most EV+3 more exposure for the same scene than would a dedicated UV lens. This requirement is the one with which most ordinary lenses cannot adequately cope. It is unlikely that any modern multi-coated, multi-element lens can be truly designated as a UV-capable lens. If the aim just is to detect flower patterns, such a lens might do adequate service in the 380 - 398 nm range. However, this in no way ensures the lens will render all there is of floral UV signatures or UV signatures of other subjects. For this reason alone using a UV-dedicated lens or a non-dedicated, but very UV-capable lens is advantageous. There's no predicting whether a given lens is UV-capable if it was not specifically designed for UV shooting. As noted, with a very long exposure an ordinary lens can often leak enough near-UV to produce an image, but it likely will not record the fine surface details that UV can reveal. What we can say generally about non-dedicated, UV-capable lenses is that they tend to have the following construction: Uncoated elements Little or no element cement. If cemented, cement must be non-fluorescing. A small number of elements, 3 or 4 Of course, there are some exceptions to this general rule. Do note that most non-dedicated, UV-capable lenses have an axial chromatic aberration problem called 'focus shift' to deal with (see later). Birnian Rule of Thumb for UV-Capable Lenses from Birna Rørslett A decent UV-capable lens should require at most 3 stops more overall compared to the Nikon 105/4.5 UV-Nikkor or the Coastal Optics 60/4 APO. Measuring UV Transmission of a Lens I asked member Shane Elen what was needed to accurately measure the UV transmission of a given lens. from Shane Elen Ideally you need a CCD spectrometer, or spectrophotometer (preferably in a dual beam configuration) with a monochromator, an integrating sphere, and a stable output UV-V-IR source. The integrating sphere helps ensure that the readings are independent of the incoming light ray angle. This will provide you with wavelength specific transmission response. To informally test UV lens transmission, it is possible to collect a set of narrow UV bandpass filters, mount them in some kind of holder and estimate a lens UV transmission by taking a UV photo of the mounted filters. Although the idea has been used before, Steve Smeed was the first in recent years to implement mounted UV bandpass filters in his clever Sparticle Board. Here is another example shown in an article by Enrico Savazzi: Filter Strip for Testing UV Lenses. See also Links to Informal Lens Transmission Tests. UV Focus Shift Focus shift between the Ultraviolet & Visible wavebands in a lens is a form of axial chromatic aberration that occurs because shorter, higher frequency UV wavelengths focus at a different distance along the longitudinal axis of a typical lens than do longer, lower frequency Visible wavelengths. Such wavelength-induced focus shift is a topic of particular interest in UV photography when using an external filter and a camera that has no Live View. First you must focus the lens in Visible light before mounting the dark UV-pass filter. After mounting the filter you might have to adjust your initial focus if the lens has not been designed to also bring the UV rays to the Visible plane of convergence. With a bit of trial and error you should be able to determine the proper correction at various apertures and note it for future reference. UV focus shift is less of a worry with an internal UV filter because during conversion the auto-focus can be adjusted a bit to compensate for UV for most lenses at most apertures. Focus shift is not problem at all when using Live View if you have sufficient UV illumination. Attaining sufficient illumination to use Live View for focusing in the UV case is not always easy especially for UV between 300-350 nm. Other Lens Terms of Interest Chromatic Aberration Spherical Aberration Achromatic Lens Apochromatic Lens Superachromatic Lens Diffraction In photography, diffraction is the interference of light waves with one another caused by their passage through a lens aperture. The narrower the aperture, the more the diffraction. The spreading light waves' interactions cause interference patterns around the Airy disk which is recorded on a digital sensor as a loss of sharpness in an image. In UVIR photography, a key fact to note is that longer IR wavelengths spread more at a given aperture than shorter Visible or UV wavelengths. Hence IR shots are more prone to the effects of diffraction and UV shots less so. Thus, for example, if you make a Visible light photo with a sensor & lens combo that begins to show diffraction blur past f/8, then you might have to open up your lens to f/5.6 (or larger) to shoot a sharp IR version of the same photo. On the UV side, you might be able to stop down to f/11 (or smaller) and still stay sharp. Opening up in IR to reduce diffraction must be balanced against the need for stopped-down depth of field. Some diffraction can be compensated for in the editor by various sharpening tools. Relevant Links: Diffraction Huygens-Fresnel Principle Airy Disk George Biddell Airy Lens Diffraction and Photography About the UV Lens List For a lens to be on our UV Lens List, it must have at least one member or contributer who has either used it or tested it to confirm that the lens is UV-capable in some portion of the UV bandwidth. Our lists are by no means exhaustive, so please experiment and let us know of your discoveries. Please Note the following: UV-Capability ? The amount of UV-capability of the lenses on this list varies. We have tried to list lenses that reach at least 350nm, but not all lenses have been formally tested. Investigate before purchase! Mount Type ? Many lenses on this list may need modification of the lens mount and the use of focusing helicoids and/or bellows for use on your particular camera body. Under such modification, the lens may not focus to infinity. Investigate before purchase! UV Focus Shift ? Most of the lenses listed below have some degree of the UV focus shift discussed above. Lenses without such focus shift are noted. Consider converting a camera with Live View to avoid dealing with focus shift. Investigate before purchase! Warning about Lens Scams The original UV-Nikkor 105/4.5 has become a very high-priced collectible. Prices have skyrocketed to the $4000-5000(US) range, maybe more. The lens has been seen offered at a much lower price in several lens scams across the internet. Do not fall for these scams! No one who is reputable will be selling the UV-Nikkor or any other rare UV-capable lens at a price under its current market value. Enlarger Lenses for UV An enlarger lens (EL) is used in a photographic enlarger for producing a print from a film negative. Some alternate photographic print processes require UV light to produce a contact print: cyanotype, platinum/palladium, gum, carbon, Kallitype and Van Dyke. So, most ELs pass some ultraviolet light between 370-400nm, some beyond that. But note that there is no generally accepted range of UV transmission for ELs. The range will vary by brand and lens construction. Enlarger lenses also, of course, magnify and have a flat-field construction. So ELs can be very useful for UV macro work when reversed. There are several enlarger lenses listed in the Lens Sticky, but it is not intended to be exhaustive. Use what is listed there for further explorations and experiments. Enlarger Lens References: Enlarger Lenses in Photomacrography by Enrico Savazzi Reversed Enlarger Lenses by Johan J. Ingles-Le Nobel Ultraviolet Light Sources for Printing with the Alternative Processes by Sandy King 35mm f/3.5 Lenses for UV - not the only category Any reader of the lens lists here in this Sticky will have noticed a predominance of non-dedicated, UV-capable lenses in the 35mm f/3.5 category. As has been remarked elsewhere, simply constructed lenses with minimal coatings and no UVIR-reflecting or fluorescing glues or other fluorescing or problematic inner parts, have been proven useful for UV imaging. Many of the older 35/3.5 lenses with manual apertures or preset apertures fall into that category. Read this post by Enrico Savazzi for a bit more insight into this: 35mm lenses for UV photography. With the research done by Klaus Schmitt, Enrico Savazzi and others and several nice 35/3.5 finds made by Oleksandr Holovachov, Steve Smeed and others, we have accumulated a good listing of UV-capable 35/3.5s. This, of course, has spurred others to look into this category where they discovered that there were quite a few UV-capable 35/3.5 designs produced by various non-mainstream lens manufacturers. And nice discoveries; were also made in the associated 105/3.5 and 135/3.5 categories and listed here. This is not to say, however, that there are no UV-capable lenses in other categories. There are indeed quite a few. Reed Curry, for example, has found many UV-capable lenses in Exakta mount which are not 35/3.5s: see Exackta Lens List (Partial) for more about Exackta lenses in general. UV shooters such as Boon Tang, Vivek Iyer and Igor Butorsky have found other good UV-capable lenses outside the 35/3.5 category which are listed below. So let us keep up the search! We will continue to add some examples of non-dedicated, UV-capable here as they are brought to our attention. Contributors to the UV Lens List Alex H = Oleksandr Holovachov annedi = Andrea Blum anon = Anonymous brianc1959 = Brian Caldwell Cadmium = Steve Smeed enricosavazzi = Enrico Savazzi igoriginal = Igor Butorsky kds315 = Klaus Schmitt nfoto = Birna Rørslett overmywaders = Reed Curry RKPhotog = Bob Kerr Vivek = Vivek Iyer

UV highlights often record non-linearly. I can take a shot and, upon review, the histogram might show exposure peaking near the middle. Add perhaps 1/3 to 2/3 steps more exposure and the histogram is close to or crashing into the right side. This is all done with EL-Nikkor closed down to the same aperture and camera on manual. Light appears the same. Is there something about UV light that causes this? Thanks, Doug A

EDIT: 13th September 2019. These lenses apparently aren't original Resolve Optics 60mm ones. They were reverse engineered by another company. Currently on ebay there is a company selling second hand forensics imagers called Sirchie Krimesite cameras. As far as I can tell, they are using the 60mm f3.5 Resolve Optics UV lens shown here; https://www.resolveo...-forensic-lens/ The ebay link is here; https://www.ebay.co....~0AAOSwHcNc-TVG They have a variety for sale, including full forensics setups, but the one in the link above is cheaper than a full setup and includes the filter holder (which some of the others don't have). I spoke briefly with Resolve Optics earlier, and asked about a new price for one of their lenses. They did not want to give that info out, however when I asked if it was more than £1000, the answer was, "oooh yes". I have no affiliation with the ebay company selling these, however I have bought one myself (which I wont see until November when I next see my family in the US). They accepted an offer of $700 for one. I'm sharing in case it is of interest.

This is a stretch of the forum's general theme as its link to UV is only the recent topic about hummingbirds. This is only partly about visual iridescence. I hope I am forgiven. Last week I was out searching for suitable sites for photos when I stumbled over something I think are very interesting. I had heard about a small nature preserve with bank swallows. When I got there, without any camera, I found a group of nice ornithologists too looking for a more rare visitor, the Bee-eater. They had cameras with fast loong fast tele lenses. The sand bank is fenced off to protect the bank-swallow colony. You have to stay maybe 40m back from the brink. That beautiful bird is rarely seen at my latitudes. It has happened a handfull of times this millennia. It was a privilege just to see the bird hovering in the sky. There is/was a pair feeding small ones inside a deep nest hole in the sand bank. I decided to try to get some images myself. The following day and the day after I got there better equipped and had some luck. The first day the birds only took dragon flies, the second I saw bumble bees, butterflies, and bees in their beaks too. Here are a few of my better images. The last five are from a bird-landing sequence taken at 10 Frames/s Telyt 560/6.8 + novoflex 1.5x extender all images except for the sky image, then Canon EF 400/4.0 IS + EF 1.4x extender

[UV SAFETY] UV-C Light Is Dangerous NEVER look at a UV-C light. NEVER let UV-C light hit your skin or eyes directly or by reflection. UV-C light can cause: severe burns of the eyes and the skin, and DNA damage from broken chromosomes. When working with UV-C illumination, you MUST: cover up completely, wear head & eye protection, and have strong ventilation. Hi, I know this was asked in other threads, but can we make some kind of summary about available UV-C options? To be honest, I can't even find one best light source & filter for this, so I think such kind of topic is needed. I know that there are UV-C light sources like: - low pressure Hg lamps (but are they enough to photograph with, can we have a summary about a distance they are able to lighten so any picture can be made?). - excimer lamps (like 222nm) - aren't they too weak to do any photo with them - I see only input powers but not actual UV-C output when shining at anything from, say, 50cm away? - others? Regarding filters or stacks - I literally find no option. Every filter I see is either just a band-pass filter that only passes 20nm width around some UV-C frequency and then has IR leaks that would make it useless, and if you want to block IR with S8612 then no way - S8612 and similar block UV-C). So I can't find any usable filter, not even speaking about having it in 52mm thread or any similar, they are usually tiny, specific for some laser etc. So can we list possible, most powerful UV-C light sources and possible (if any) filters?

Finished with all the posts, feel free to read and reply Triggered by Kai's thread (https://www.ultravioletphotography.com/content/index.php?/topic/5345-uv-photography-with-a-tilt-lens/), I decided to run some tests of the T/S-lenses. For this, I used the ones I have (17, 24), plus some which I managed to borrow from a friend. I might try to find one of the longer T/S-lenses on ebay, as they are fun to work with. Fortunately, today's weather was overcast, so I managed to get the shots with about the same lighting conditions (at the end I had to hurry else it would have been lightning conditions ). Cameras: UV: Canon EOS 6D, UV b/w by Maxmax IR: Canon EOS 6D, 700nm conversion by Sven Lamprecht VIS: Mobile phone Lenses: TS-E 17mm f/4 L TS-E 24mm f/3.5 L II TS-E 45mm f/2.8 TS-E 90mm f/2.8 TS-E 135mm f/4 L Macro Extenders: Canon Extender 1.4 II Canon Extender 2.0 II I had the cameras mounted on a tripod, but with every change of lenses or filters the position will have changed just a little bit; also I did not take the photos in the order in which I present them, so don't be suprised if there is large change in the field of view. Finally, focussing was a bit tricky (will have to get some reading glasses or one of those magnifying gadgets for the camera), please don't be too harsh. This is especially true for the UV-photos with the 90mm-lens. Five of the UV-shots are takens with an additional S8612 filter, just to get rid of any IR-leaks. I've observered many times, that the S8612 is not really neccesary, escpecially with my Soligor 21mm, but decided to make sure; and indeed, there are couple of shots where there is a difference. Due to the upcoming thunderstorm, I only had time to do a full test in normal-position, plus a couple of tilted or shifted shots with two lenses in UV. I might try another test with my FS-camera in the next couple of weeks, just to see how deep the lenses go into UV, perhaps also some more fun with tilt/shift; but don't hold your breath, work is interfering a lot at the moment. Processing: UV: I only converted to b/w (ooc there is some blueish tinge to the photos) and did global adjustment of exposure, to get the histogramms close to each other. The exposure is noted in the description of the photos. IR: CLiR profile number 5, no further adjustments (there are some differences in the colour casts of the lenses) VIS: nothing If you're interested what's in the photos, it's nothing exciting, just a view in my home-town of Leonding in Austria. Chose this spot because it's not too far away from my place, and it has grass, a field, trees, some buildings, and sky in it. Export was done from lightroom, 1500px long edge, quality 100%. Now, without further ado, the first photo, VIS: