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I got the UG5 to simulate bee vision -- did not really want to combine visual and UV shots to achieve that (call me lazy). This is natural since for my day job I study honey bees. I did not get the nicer green from what UVIRoptic did. He says I have to finetube my white balance. I used in camera white balance, then used Photo Ninja again (using the same white Teflon as reference, for photo2). shot with G5, S8612 (1.75mm) + UG5 (2mm). photo 1. black eyed susan (plenty in my garden). photo 2. black eyed susan on the block of white balance reference. I used Photo Ninja to WB again so the white looks pretty white to me, but the green did not change. UG5's ebay image: http://i.ebayimg.com/00/s/NDQwWDE0MDA=/z/Me4AAOxy3HJTGlcX/$_57.JPG

Here are some thoughts about where "red" may come from in some of our UV images. It is nothing new, but a useful reminder. (Spoiler warning: it may come from at least three different spectral regions) Let's start first with an ordinary Trifolium cf.pratense: VIS (Baader UVIR Cut). Abundant pink, the initial assumption is that this pink comes mostly from the red portion of the VIS spectrum. UV (Baader U). The typically dark, slightly ruddy appearance of highly UV-absorptive flowers. The little red/violet in it should be mostly or exclusively UV recorded as false color. There might also be a (very) little violet leaking in from the short-wavelength end of the VIS spectrum. Normally there should not be any detectable IR contamination with this filter. UV and some VIS blue and violet (stacked Schott BG40 and Thorlabs FGUV5, the latter is an antireflection coated Schott UG5). This rather striking rendering contains lots of blue, but also some red. Most of the blue is false-color UV just below 300 nm. Quite a bit of it is also VIS blue leaking through the "tail" of the UG5. VIS red and NIR are cut away by the BG40, so we can rule them out. We can rule out NIR also because the typical appearance of flowers in NIR is uniformly washed-out reflection, not concentrated in a few spots like we see here. The remaining possibility is the violet region of the VIS spectrum. The red-sensitive pigments in our eyes have a second peak in the violet region, and this is how we can distinguish violet (for us, red + blue) from blue. The pigments used in Bayer sensors are intended to mimic our color sensitivity, and the red filters of Bayer sensors also transmit in the violet region, in addition to red. Mostly UV around 325 nm (325BP10). This UV region is recorded as yellowish green by Bayer sensors. However, with this filter some subjects also produce a bit of orange (which I pushed up in post-processing to make it unmistakable). There is no visible leak with this filter, nor there is any significant transmission of UV above 350-360 nm. The red channel in this case must be recording a NIR leak. Using a fluorescent UV source instead of electronic flash removes all red, which proves the point (UV fluorescent tubes produce very little NIR). Stacked Schott BG40 and Thorlabs FGUV5, electronic flash. Quite a bit of pink, in this case perhaps part from UV false color, part from the violet region of VIS. However, the flower looks uniformly yellow in VIS. Stacked Schott BG40 and Thorlabs FGUV5, "UV-C" reptile fluorescent tube (actually produces UV-B, UV-A and some visible). The flower looks quite different, but not the background. I cannot really explain these differences yet. I did no post-processing, no color channel swapping, no color remapping in this or the preceding image. Perhaps it has to do with the fact that these fluorescent tubes produce a concentrated emission at a number of spectral lines, while electronic flash has a more continuous spectrum.

I read somewhere recently that the Bayer filter over the sensor typically absorbs 2/3rds of the incident light. This makes sense if the photons are in the wavelengths antithetical to the dye. So, if the light is green and the cel green, the R and B don't make it through to the sensor. That is, however, a loss that the human eye, for example, doesn't experience. Here is the normalized absorption spectra of a trout's retina (sorry, didn't have time to dig out a human's): http://overmywaders.com/images/4graphs.jpg As you can see, a photon at 390 nm striking a trout's Red cone will be absorbed by the opsin slightly less than the Green and the Blue - which appear equal at that point. However, no matter the cone type, the 390 nm will be absorbed by, and activate, the opsin of that cone. [Even better with the rods.] What does the absorption spectra for the Bayer filter look like? Do we get the same benefit from RGB at 390 nm as in the graph above? Sorry if this is a stupid question. I'm not fully caffinated yet but curious nevertheless. :)

I have made up & tested the ‘UV Sparticle BandPass Filter Array’ with the Sigma DP2 full spectrum camera & photographed the results. https://www.flickr.c...57644733838706/ Let me know what I can do better please ? Cheers Col

A recent thread by Dave: http://www.ultraviol...olour-spectrum/ and Andrea's reply to it: "Seems like with the Baader-U we get mostly blues, yellows and some very dark greens in UV False Colour Land - or maybe they are very dark cyans, not sure which. It is all a bit tricky nailing down the false colours because of little differences between editors, sensors, bayer filters, lenses, lens coatings and so forth. Then, of course, that colour list can change quite a lot once you stray from the Baader-U. The greyed-blues always look lavender/purple to me. And greyed-yellows look more greenish. Never have gotten any bright greens with the Baader-U." reminded me of some images that I had taken from Scilla bifolia. Unlike most of the times when leaves are pretty dark in the UV-image, they appear cleary (dark) green. WB was done against PTFE like in my other UV-images. I've no explanation why these leaves turn green and I have not seen this effect again since then ... Scilla bifolia. Images taken near Biblis, Germany. 4 March 2013. Images taken with the Panasonic Lumix G1 broadband modified and the EL-Nikkor 80 mm/f5.6. Visible light image: Baader UV/IR cut filter Image reference:NCH-1070564 UV-Image: Baader U filter. Image reference: NCH-1070567

I thought I had posted this on NG, but couldn't find it to reference here. So maybe I didn't. D300-broadband with no internal clear glass filter. 290BP10 UV-Pass filter. Some UV lens, probably either the Ultra-Achro-Tak or the UV-Nikkor. Its written down somewhere but of course I cannot find those notes. (The EXIF is incorrect about the 58mm.) ((Bjørn will now remind me to chip my lenses. :D )) A pair of grocery store Sunflowers in the sunlight. Visible with Baader UVIR-Cut Filter f/5.6 for 1/4000" @ Iso200 UV with Baader-U UV-Pass Filter f/5.6 for 1/2" @ Iso200 This photo is ever so slightly 'flat', I think, because I didn't use the UV-Flash. UV with 293BP10: the original converted to jpg, no edits, no attempt to white balance. f/5.6 for 156" @ Iso200 with Incandescent WB UV with 293BP10 Edit 1: tweak contrast. UV with 293BP10 Edit 2: tweak B/W points, shadows. UV with 293BP10 Edit 3: boost saturation, play with colours a bit. This revealed a light leak? I was holding the filter onto the lens by hand. UV with 293BP10 Edit 4: deal with noise.

STICKY LIST Sticky :: SWIR Photography: Cams, Mods, Lenses, Lights, Links Sticky :: UV-Capable Lenses Sticky :: UV/IR Books Sticky :: UV/Vis/IR Filters (You are here.) 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/Vis/IR Filters by Andrea G. Blum for UltravioletPhotography.com [LAST UPDATE: 1 Nov 2023 Added reference to Best Basic Gear.] 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 at ultravioletphotography dot com. Abbreviations: IR = infrared UV = ultraviolet UV/IR = 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 receives no compensation or income from any source.] CONTENTS UV/IR FILTERS Introduction Filter Care Shooting with Shiny-sided or Dichroic Filters FILTERS and GLASS: IR-PASS Filters: IR-Pass Filter Glass: IR-Pass FILTERS and GLASS: UV-PASS IR Leakage in Some UV-Pass Filters Filters: UV-Pass with Minor or No IR-leakage Filters: UV-Pass with Unknown IR-leakage Filters: UV-Pass with Major IR-leakage (Dual Bandpass) Filter Glass: UV-Pass Filter Stacks: UV-Pass + IR-Block FILTERS and GLASS: IR-BLOCK Filters: IR-Block Filter Glass: IR-Block FILTERS: UV/IR-BLOCK (Visible Pass) UV/IR FILTERS Introduction When referencing filter transmission and blocking ranges, the reasonable assumption is made that Visible light covers the range 400-700 nm, Ultraviolet light is the range 300-400 nm, and Infrared light has a 700-1100 nm range. These divisions cover the approximate range of a converted digital camera sensor. The filters listed here are all pre-mounted and circular. Non-circular filters can of course be used in appropriate adapters and links to any such filters are welcomed. We have tried to give both a manufacturer's link for each filter brand and link to a transmission chart. Because Hoya or Schott glass is a reference standard and used in the manufacture of many filters, it is also discussed. Please Note: Stated transmission ranges are approximate as charts may be difficult to read or not precisely accurate. Also, a manufacturer's transmission chart may be for a thickness standard that is not necessarily the thickness used by a finished filter supplier. Less reputable finished filter suppliers may provide a manufacturer's chart that is not valid for the thickness of their supplied filter. Filter Care Clean your filters carefully after use and before storage. Blow off any dust and particles with a bulb blower. Use a cleaning fluid that is made for use on coated filters. Clean and dry with a microfiber cloth or lens tissue because some coatings or special glasses are easily scratched. Dust, pollen, perspiration and contact with stronger acids or alkalines can damage filters. Some filters may deteriorate over time from solarization effects due to overexposure to Ultraviolet light. Chemical changes such as oxidation of the glass or of the coatings can also occur especially on uncoated filter glass. And fungus can attack filter glass or filter coatings just as it attacks lenses. If a filter becomes filmy or sticky or develops small crystals, clean it immediately to preserve it for future use. Oxidation on uncoated or unclad filters can be delayed by storing filters with dessicant packs. Using hydrogen peroxide or a fine-grade cerium oxide glass polish can remove light oxidation. Regular cleaning will prolong the life of all filters. Store filters as you would store your lenses - in a warm, dry place. See more about filter care in the later section Filter Stacks: UV-Pass + IR-Block. Shooting with Shiny-sided or Dichroic Filters One problem with hard-coated, shiny-sided filters is that they can sometimes induce reflections and flare within the lens barrel and/or camera chamber from any entering light, but most particularly from off-axis light. The reflections can cause a general lack of contrast or create interesting annular patterns in the photo in addition to the typical aperture-shaped light blobs along a diagonal. Ideally with such shiny filters, the photographer remembers not to shoot contra jour. Move yourself or your photographic subject to prevent backlighting. Turning the shiny filter side outward to face the photographic subject, using a lens hood and rear mounting a small version of the filter all help mitigate potential reflection and flare problems. With a filter like the UV-pass BaaderU, just as one example, 98 times out of 100, you won't see any problem from its shiny side. But some hard-coated (industrial) filters with two very shiny mirrored surfaces cannot be adapted for general outdoor UV photography and are extremely difficult to use in the studio as well. Informal observations indicate that transmission of the desired wavelengths is not affected by which direction the shiny side of a filter is facing. A dichroic filter also can create some concentric discoloration on the edges of a photo. It is often observed when the dichroic filter is used over a wide-angle lens but may also occur with longer focal lengths. Dichroic discoloration in a long focal length photo can be easily cropped away. In either a narrow-angle or a wide-angle photo, such discoloration can often be mitigated by a suitable monochrome or split-tone conversion and use of vignetting tools. An example can be found in one of the SEU Gen2 filter tests: Monochrome Conversions of Dichroically Discolored Photos FILTERS and GLASS: IR-PASS Note that "red leak" mentioned below in conjunction with IR-Pass filters is not a bad thing. Many IR photographers want a bit of red leak in their IR photos because it can be manipulated to give pleasing IR false colour by red/blue channel swapping or other processing techniques. Filters: IR-Pass Listing order is alphabetical by company. Order does not imply preference. (1) Baader-Planetarium IR-Pass Filter #2458386 The Baader-IR transmits above 685nm, passes high red + IR and has some IR false colour capability. Transmission chart is not currently available. Baader filters may be found at many astrophotography and astronomy retail/online shops as well as at Baader-Planetarium. Baader-Planetarium GmbH Home page. In German. Baader-Planetarium GmbH Home page. In English. Baader Filters Baader filter types with further links and search. Baader IR-Pass Filter General information, examples, articles. 2" and 1.25" versions available. (2) B+W 099, 092, 093 IR-Pass Filters B+W 099 passes orange, red & IR, reaches 50% transmission at 550nm, has IR false colour capability. B+W 092 ("dunkelrot") passes high red & IR, reaches 50% transmission at 695nm, has some IR false colour capability. B+W 093 ("schwarzrot") passes IR only, reaches 50% transmission at about 830nm. Schneider-Kreuznach Home page of parent company. (In German) B+W Photo Filters General information. B+W Filter Types B+W IR-Pass Filters Both B+W 092/Dunkelrot-695 and B+W 093/Schwarzrot-830 are on same page here. Schneider Optics Home page of U.S. subsidiary of Schneider Kreuznach. B+W Filter Handbook PDF. B+W IR filters are on page 29. Transmission charts on page 61. B+W 092 Spectral Analysis by Shane Elen. Scroll down. B+W 093 Spectral Analysis by Shane Elen. Scroll down. (3) Heliopan RG Series IR-Pass Filters Heliopan IR-Pass filters are made with a Schott glass substrate.RG645/665/695/715 pass IR & red (in varying amounts) and have some IR false colour capability. RG780/830/850/1000 pass only IR. Heliopan Home page. In German. Heliopan Filters for Digital Photography PDF. In English. Heliopan Infrarotfilters In German. A small combined transmission chart is shown. (4) Hoya R Series, RM Series IR-Pass Filters Hoya IR-Pass filters are made with a Hoya glass substrate, of course.R-70, R-72 pass high red & IR, reach 80% transmission at approx. 745/765nm and have some IR false colour capability. RM-90, RM-100 pass IR only and reach 80% transmission at approx. 1050/1200nm.The IR transmission cut-ins begin at 700/720/900/1000nm, respectively.These are the pre-mounted, circular filters which are commonly available.See the Hoya glass entry below for more information. Hoya Candeo Corp Company profile. Hoya Colored Glass Filters List. Hoya IR Transmitting Filters Combined transmission chart. Data given below that. (5) LifePixel IR-Pass Filters for Internal Conversion of Camera LifePixel is a retail camera conversion shop. There are five internal IR-pass filters used in their conversions: Deep BW (50% at ~825nm), Standard (~710nm), Enhanced Color (~665nm), Super Color (~600nm) and Super Blue (~275-460nm in UV/violet/blue and ~710+ in IR). LifePixel Home page. LifePixel IR-Pass Filters Transmission charts.On this FAQ page, scroll down to the question"What kind of filters do you use for conversions?" and click it to see charts. (6) MaxMax X-Nite Series IR-Pass Filters R + IR: X-Nite 630/665/715 with some IR false colour capability. X-Nite 780/830/850/1000 pass IR only. (These look like Schott glass numbers?) MaxMax (LDP LDC) Home page. MaxMax (LDP LDC) Table of contents. X-Nite IR-Pass Filters Transmission charts. (7) MaxMax BP Color Series IR-Bandpass Filters This set of 3 IR-bandpass filters might enable an interesting RGB channel mapping from the IR band. Note that the shiny metallic surface of these filters indicates that they are dichroic. With a dichroic filter, transmission varies with incidence angle and can lead to variable wavelength performance across the filter, especially for wide angle lenses. Longer wavelength IR is more affected by this. MaxMax (LDP LDC) Home page. MaxMax (LDP LDC) Table of contents. BP Color Series BPR, BPG, BPB. Scroll down. BPR transmits 50% between 662-753nm. BPG transmits 50% between 795-860nm. BPB transmits 50% between 921nm-958nm. (8) Peca 900 Series IR-Pass Filters These filters are sold in a 62mm mount size. Peca 902/914 pass high red & IR and have some IR false colour capability. Peca 908 passes some violet/blue/UV below 450nm, but has no red or near-IR leak. Peca 904/906/910 pass IR only. Peca 912 is a wideband IR-pass between appox. 700-1200nm. Peca Home page. Peca IR-UV Filters List. Peca 902 Filter Wratten #70. Peca 904 Filter Wratten #87. Peca 906 Filter Wratten #87A. Peca 908 Filter Wratten #87B. Peca 910 Filter Wratten #87C. Peca 914 Filter Wratten #89B. (9) Singh-Ray I-Ray IR-Pass FilterThis filter is advertised to transmit 90% of near-IR light between 700-1000nm. No transmission chart is currently available. Singh-Ray Filters Home page. Singh-Ray I-Ray Information. (10) Tiffen 87 IR-Pass Filter The filter transmits above 725nm, so is IR-pass only. Tiffen Home page. Tiffen Filters General info with more links. Tiffen 87 There no longer seems to be specific info on the Tiffen website about this IR-pass filter. Tiffen 87 Spectral Analysis by Shane Elen. Scroll down. . Filter Glass: IR-Pass Listing order is alphabetical by company. Order does not imply preference. (1) Hoya R, IR, RM, RT Series IR-Pass Filter Glass Hoya Candeo is a Japanese manufacturer of optical products including filter glass and pre-mounted, circular filters. Their glass is used by many photographic filter manufacturers. In addition to the R and RM series glass used in Hoya mounted filters listed above, the chart shows IR 76N, 80N, 83N and 85N glass with IR transmission cut-ins beginning at 760/800/830/850nm, respectively, and having a 60nm interval prior to reaching peak transmission (not given). Hoya Candeo Optronics Corp Company profile. Hoya Colored Glass Filters List. Hoya IR Transmitting Filters Combined transmission chart. Data given below that. (2) Schott RG Series IR-Pass Filter Glass Schott AG is a German manufacturer of optical products (and other products). Their glass is used by many photographic filter manufacturers. The Schott "RG" prefix denotes IR transmitting glass. The number indicates the wavelength where 50% IR transmission is reached. R + IR: RG 9/610/630/645/665/695/715 with some IR false colour capability. IR Only: RG 830/850/1000. Schott Advanced Optics Home page. Schott Optical Filter Glass Links to all filter glass data sheets. Schott Optical Filters 2013 PDF. Optical filter catalog. RG9 RG610 RG630 RG645 RG665 All PDF data sheets with transmission charts. R695 R715 R780 R830 R850 R1000 All PDF data sheets with transmission charts. FILTERS and GLASS: UV-PASS Editor's Note: I have decided to be out of the business of judging how much IR leakage any of these UV-Pass filters have. Learn how IR leakage can contaminate a UV photograph and be sure to examine the transmission charts for any filter you buy. Dual Bandpass of UV+IR in Some Old UV Filters and in Filter Glass The filter glass substrates used to make UV-pass filters are dual bandpass with significant transmission in the IR range. (Reference below Filter Glass: UV-Pass.) To create an UV-pass only filter, dichroic coatings, hard coatings or ionic layers are added to the filter glass to block IR. We recommend that you look for IR-blocking between at least OD3.5-OD4.0, (more is better), for use in digital UV photography. Some older UV-pass filters created for use in astronomy or for use with UV-film do not reach the OD3.5 level of IR blocking because that was not needed when using IR-insensitive UV-film. For example, the old BaaderU, the ScheulerU or the B+W 403 will not work well for digital UV photography due to IR contamination. To use one of those dual-bandpass filters successfully for digital UV photography, you must stack it with an IR-blocker made from some type of blue-green glass such as the Schott 8612. (Reference below Filter Glass: IR-Block.) Dichroic, hard-coated UV-pass filters or commercial ionic UV-pass filters are typically quite expensive. A less expensive approach to UV-pass filtration is achieved by stacking one of the Hoya or Schott dual-bandpass (UV+IR) filters together with a IR-blocker made from some kind of BG glass. This do-it-yourself stacking saves some money, but you must remember to frequently check your uncoated filter stacks for possible oxidation. It is mentioned above in Filter Care that hydrogen peroxide baths or fine-grained glass polish can remove early signs of oxidation. Filters: UV-Pass with Minor or No IR-leakage Listing order is alphabetical by company. Order does not imply preference. (1) Baader-Planetarium BaaderU UV-Pass Filter #2458291 350FWHM60 This absorptive/dichroic UV-Pass filter transmits 78% at its peak of 350 nm. Its half-maximum range of greater than 39% transmission is between 320-380 nm. The BaaderU has a Schott UG11 absorptive substrate with dichroic (interference) coatings. The filter was developed for astronomy and may be found at many astrophotography and astronomy retail/online shops as well as at Baader-Planetarium. It is available mounted in 2" and 1.25" sizes. Prior to photographic use, it is recommended that the BaaderU be reversed in its mounting ring so that the pink side faces the subject, not the sensor. When the pink side faces the sensor there can be increased internal flare off its highly reflective surface. The orientation of the filter does not seem otherwise affect the UV image although the pink side is supposedly more IR-reflective. With a dichroic filter, transmission varies with incidence angle and can lead to variable wavelength performance across the filter, especially for wide angle lenses. Be sure to read above: Shooting with Shiny-sided or Dichroic Filters. A conversion suggestion for wide-angle dichroic discoloration is mentioned there. Editor's Note: I have seen some vignetting with the BU on some lenses because of its 2" size. This might be cured with different step-rings or rear mounting. Baader-Planetarium GmbH Home page. In German. Baader-Planetarium GmbH In English. Baader Filters Types with further links and search. Baader U-Filter 2" General information. Baader U-Filter 2" Photo. Baader U-Filter 2" PDF info sheet. Baader U-Filter Transmission Chart I'm not sure the chart shows the claim of 350fwhm60? Baader Ultraviolet Transmission Filters Spectral Analysis by Shane Elen. The Baader UV Filter By Enrico Savazzi. In English. Baader Planetarium U Filter By Company 7. In English. (2) Kolari Vision UV Bandpass Filter 365FWHM40 This absorptive/dichroic UV-pass filter transmits 50% at its peak of 365 nm. Its half maximum range of >25% transmission is between 340-380nm. The minimum OOB rejection is 3.5O OD with an average of 4.3 OD. Substrate info is not provided. On a wide-angle lens the KU will not have the peripheral colour banding sometimes seen with filters having dichroic coatings. Kolari Vision Home page. Kolari Vision UV Bandpass Filter Filter listing with photo. (3) UVR Optics (UVR Defense Tech, Ltd.) Offerings regularly change. Check the home page for the latest. UVR Optics Home page. Filters: UV-Pass with Unknown IR-leakage I'm going to list here a new UV-Pass filter which has not been tested by any of our members but for which the specifications look good. (1) Astrodon UVenus UV-Pass Filter Astrodon has discontinued their Astrodon-Schuler UV-Pass filter. They are now offering a hard-coated UVenus filter which has an average UV transmission of about 90% between 325-381 nm. The filter has a fused silica substrate. The non-UV leakage is given as less than .1% between 420-1100nm, but we have not yet had anyone test this filter for photographic use. It is available in a 1.25" mounted size and a 49.7mm unmounted size. Astrodon Home page. Astrodon Filters Products. The UVenus Filter Includes transmission chart. . Filters: UV-Pass with Major IR-leakage (Dual Bandpass) Listing order is alphabetical by company. Order does not imply preference. RECOMMENDATION: You must stack an IR blocker over these filters for use on a digital camera. See "IR Leakage in Some UV-Pass Filters" above. (1) B+W UV Black 403 UV-Pass Filter This dual bandpass filter transmits 320-385nm (50% bandwidth) with a large IR bump around 740nm (approx 50% transmission). Most visible light is blocked although there is still a 10% toe at 400nm, so a bit of violet/blue is leaked. The 403 must be used with an IR-block filter to prevent IR contamination of a UV photograph. This filter has a UG1 substrate. Note that some of the English translations are incomplete in the following links. Schneider Kreuznach Home page of parent company. (In German) (In English) B+W Photo Filters General information. B+W Filter Types B+W 403 UV-Pass Filter (In German) (In English) Schneider Optics Home page of U.S. subsidiary of Schneider Kreuznach. B+W Filter Handbook PDF. B+W 403 is on page 27. Transmission chart is on page 61. B+W 403 Spectral Analysis by Shane Elen. Scroll down. (2) MaxMax X-Nite 330 UV-Pass Filter This filter transmits up to 78% UV between 240-400nm with a peak at 330nm and a 10% IR leak around 720nm. MaxMax recommends that it be used with their X-Nite BP1 filter to prevent IR contamination of a UV photograph. This will affect UV transmission below 300nm in case you have a lens that can transmit UV that low. MaxMax (LDP LDC) Home page. MaxMax (LDP LDC) Table of contents. X-Nite UV-Pass Filter Transmission charts. Scroll down. (3) Peca 900 UV-Pass Filter This filter transmits approximately 250-400nm with a 25% IR bump around 715nm. It must be used with an IR-Block filter to prevent IR contamination of a UV photograph. (A Peca UV-Pass 901 is listed but the link is broken for its transmission chart.) Peca Home page. Peca IR-UV Filters List. Peca 900 UV-Filter Transmission chart. Labeled as equivalent to a Wratten #18A. . Filter Glass: UV-Pass Listing order is alphabetical by company. Order does not imply preference. It is important to briefly discuss the types of glass commonly used as substrates in UV-pass filters to better understand their construction and characteristics. View the linked transmission charts directly for the most accurate analysis of each type of glass. (1) Hoya U Series UV-Pass Filter Glass Hoya Candeo is a Japanese manufacturer of optical products including filter glass and pre-mounted, circular filters. Their glass is used by many photographic filter manufacturers. The number indicates the peak UV wavelength of each filter.Currently only U-330/340/360 are listed by Hoya. The U-325C and U-350 seem to no longer be produced.Uncoated or unclad glass may be prone to oxidation. Store U-glass with a dessicant and regularly polish it with a cerium oxide glass cleaner. U-330 Maximum UV transmission of approx. 85% for 2.5mm thickness between 230-400nm.Leaks small amount (less than 10%) of violet/blue between 400-420nm.Big IR leak beginning at about 650nm, peaking at 50% around 720nm. U-340 Maximum UV transmission of approx. 78% for 2.5mm thickness between 260-400nm.Leaks IR between 680-740nm, peaking at 3% around 720nm.WARNING: There is yellow-green visible leakage from thin versions of U-340 filter glass. For example, at a 1.0mm thickness you can easily see the U-340 greenish leak. Go thick when purchasing U-340 glass for use in UV-pass work. U-360 Maximum UV transmission of approx. 72% for 2.5mm thickness between 290-400nm.Leaks IR between 700-800nm, peaking at 10% around 740nm. Hoya Candeo Optronics Corp Company profile. Hoya Colored Glass Filters List. Hoya UV Transmitting Filters Data and transmission charts. Hoya U-330 Spectral Analysis by Shane Elen. Scroll down. (2) Schott UG Series UV-Pass Filter Glass Schott AG is a German manufacturer of optical products (and other products). Their glass is used by many photographic filter manufacturers. The Schott "UG" prefix denotes UV transmitting glass.Uncoated or unclad glass may be prone to oxidation. Store UG-glass with a dessicant and regularly polish it with a cerium oxide glass cleaner or give it an overnight H2O2 bath. UG1At 1mm thickness, this glass transmits about 80% UV (at peak) between 275-425nm,passes some violet/blue between 400-425nm,is flat between 425-675nm in the Visible range,passes some red between 675-700nm, andpasses large amounts of IR (50% at peak, 5% minimum) from 700nm onwards. UG2A Info to be added. UG5At 1mm thickness, this glass transmits the most UV, up to 98%, between 225-400nm,passes varying amounts in the Visible range (50% or more at max and 1% at min),passes large amounts of IR (70-80%) starting at 700nm. UG11At 1mm thickness, this glass transmits up to 92% UV between 235-410nm,passes only a tiny amount of violet/blue,is flat between approx. 400-650nm in the Visible range,passes some red (1-20%) between 675-700nm, andpasses moderate amounts of IR (1-20%) starting at 700nm. Schott Advanced Optics Home page. Schott Optical Filter Glass Links to all filter glass data sheets. Schott Optical Filters 2013 PDF. Optical filter catalog. Schott UG1 UG5 UG11 PDF. Data sheets with transmission charts. Schott UG1 Spectral Analysis by Shane Elen. Scroll down. (3) Chinese ZWB Series UV-Pass Filter Glass Warning: Unfortunately we cannot at this time wholeheartedly recommend inexpensive ZBW UV-pass filter glass sold on Ebay because of problems with excessive striations, pits and other flaws reported by members. There also seems to be some problems with Visible leakage. (Please remember that the occasional little bubble in good filter glass or lens glass is not considered a problem.) Update: 24 August 2021. There seems to have been some improvement in the ZBW manufacturing. Some members are reporting that their ZWB filters perform well. There are still reports of excessive striations or other flaws along with refusals by the sellers to refund money. Check the forum posts to see latest discussions about ZWB filter glass. (4) Other Filter Glass Manufacturers: Kopp Glass, Newport Industrial Glass There are a lot of other optical glass manufacturers besides Hoya and Scnott. Here are two which we know about because we like their glass equivalencies charts. Kopp Glass Home page. US. Kopp Filter Glass Equivalency Guide for Kopp, Corning, Schott, Hoya, Izusu, Optima. Newport Industrial Glass Home page. US. Newport Filter Glass Cross Reference for Schott, Kopp, Corning, Hoya, Optima, Isuzu. . Filter Stacks: UV-Pass + IR-Block Manufactured, coated UV-pass filters are usually expensive. It is possible to save a bit by making a DIY stack of mounted UV-pass glass together with some type of mounted blue-green IR-blocking glass. Currently the preferred choice for IR-blocking is Schott S8612, if you can find it. If not then look for Schott BG glass. There are some possible drawbacks to stacked filters which you should be aware of. Chemical changes such as oxidation can occur on uncoated glass. Oxidation can be delayed or prevented by storing stacked filters with dessicant packs. An overnight hydrogen peroxide bath or a cerium oxide glass polish can remove light oxidation. Regular cleaning will prolong the life of stacked filters. A filter stack can induce flare. If it should occur, try a lens hood and don't shoot into the light. A filter stack may have reduced transmission of desired wavelengths. There will be more layers of glass and some air between the filters. A filter stack may require longer exposure times. As a consequence of the preceding point, a UV flash may be necessary. But then, a UV flash is almost always useful in UV photography with any filter. The UV-pass glass and IR-block glass much be carefully matched to suppress IR leakage. Study the glass transmission charts carefully to match up the IR-leaky ranges in your choice of UV-pass glass with an IR-block glass which suppresses that range - but which may very well leak elsewhere. IR leakage cannot always be fully suppressed without coatings. Even the best manufactured UV-pass filters may leak tiny amounts of IR, so the goal is to reduce IR-leak by enough that its effects are negligible on the UV photo. This goal can be aided by choosing thick enough IR-blocking glass which is yet not so thick that exposure times become painful. A filter stack can cause loss of fine detail. I'm not sure what causes it specifically, but this can look like faint fog on or around fine details. Here are some filter stack experiments I made with some known IR-leaky UV-pass filters. The results were good. B+W 403 Hoya 340 & 360 FILTERS and GLASS: IR-BLOCK IR-block filters find use in multi-spectral photography, are used as hot mirrors or are needed as IR suppressors when stacked with IR-leaking UV or Visible filters of various types. Many of the older manufactured IR-block filters are not so great at supressing all the IR. However, recently Schott has developed some new and better IR-block glass for use as an internal hot mirror in digital equipment. Ideally we shall soon see some manufactured filters made with this. Filters: IR-Block Some of the manufactured IR-block filters listed here do a rather poor job of completely suppressing the IR. The benefit of listing them here anyway is that you can avoid buying them if it is pure IR-blocking which you need. They may still be useful in filter stacks if their IR suppression interval matches another filter's IR leaking interval. (1) B+W 489 IR-Block Filter This filter, having a KG3 substrate, has a gradual slope between 700-780nm, so it transmits approximately 50% IR at 700nm. It is not recommended as an IR-block for use in UV work. Schneider Kreuznach Home page of parent company. (In German) B+W Photo Filters General information. B+W Filter Types [/b] [/i]Home page of U.S. subsidiary of Schneider Kreuznach. B+W Filter Handbook PDF. B+W 489 is on page 27. Transmission chart is on page 61. . (2) Kenko DR655 Deep-Red Cut IR-Block Filter This filter transmits from 350-700nm with a very steep slope between 650-700nm, so cuts IR very effectively. It cuts violet/blue by half between 400-450nm. Between 450-650nm the chart is bumpy. This is an interference (dichroic) type filter. Kenko-TokinaHome page. In Japanese.. Kenko Tokina Global International home page. In English.. Kenko Tokina DR655 No transmission chart. (In Japanese.) (In English) Kenko DR655 Transmission Chart [/b] 日本語で. Click third tab.DR655 Transmission Chart Featured by Lloyd Chambers of diglloyd.com . (3) MaxMax X-Nite CC1, X-Nite CC2, X-Nite BP1 Color Correction or IR-Block Filters The CC1, centered at 483nm, transmits between 310-700nm reaching below 5% transmission at 700nm and mostly suppressing the 700-900nm range. After 900nm, IR leakage climbs again. The CC1 might work well as an adjunct when stacked with some IR-leaky UV-Pass filters if the transmission charts match up.The CC2, centered at 500nm, allows significant IR leakage, transmitting between 70-40% IR between 700-800nm.The CC1 and CC2 filters are meant to be used on cameras whose Visible colour is altered by removal of the internal IR blocking filter. However, the CC2 looks a little dicey to me.The BP1 transmits between 350-700nm with a sharp right-hand slope down to 10% at about 660nm. Between 700-800nm IR leakage appears to be below 2.5%. After 800nm, IR leakage rises again. However, the BP1 works fairly well as an adjunct when stacked with the MaxMax XNite 330C UV-Pass filter. MaxMax (LDP LDC) Home page. MaxMax Table of Contents X-Nite Filters General filter info and transmission charts. X-Nite CC1, CC2, Transmission Chart Scroll down to 3rd chart. X-Nite BP1 Transmission Chart Scroll down to 6th & 7th charts. . (4) Tiffen Standard Hot Mirror IR-Block Filter Transmits 380-700nm then slopes down to about 780nm, so leaks some UV and leaks some IR with additional bumps past 780nm. No transmission chart is available from the manufacturer. We do not recommend this for use on a broadband converted camera. Tiffen Home page. Tiffen Filters List. Tiffen Hot Mirror Spectral Analysis by Shane Elen. Scroll down. . Filter Glass: IR-Block Listing order is alphabetical by company. Order does not imply preference. (1) Schott BG Series, S Series, VG Series IR-Block Filter Glass Schott AG is a German manufacturer of optical products (and many other things). Their glass is used by many photographic filter manufacturers. The Schott "BG" prefix denotes blue or blue-green glass, and "VG" denotes green glass.There are many Schott IR-block glass types not mentioned here. I've tried to choose the glass most often found as a substrate in manufactured filters. And I've listed some of the newer IR-supressing Schott glass - the newest version being VG20. Schott Advanced Optics Home page. Schott Optical Filter Glass Links to all filter glass data sheets. Schott Optical Filters 2013 PDF. Optical filter catalog. The older Schott IR-block glass is labeled BG 38/39/40/42. It transmits both UV and Visible wavelengths between approximately 300-700nm. The right shoulders of the transmission curves vary in their slopes and cutoff points.At the 700nm mark BG 39/42 in 1mm thickness are the best IR supressors at a .01% level with BG39 transmitting slightly more Visible light. Schott BG38 BG39 BG40 PDF. Data sheets with transmission charts. BG38 Spectral Analysis by Shane Elen. Scroll down. BG39 Spectral Analysis by Shane Elen. Scroll down. . The newer Schott IR-block glass is labeled BG 60/61/62/63/64. It differs from the older versions above by the addition of a protective coating against corrosion. The glass transmits both UV and Visible wavelengths between approximately 300-700nm. The right shoulders of the transmission curves vary in their slopes and cutoff points.At the 700nm mark BG 60/61/62 in 1mm thickness are the best IR suppressors at a .01% of lower level with BG61 transmitting slightly more Visible light. Schott Blue Filter Glass PDF. Product brochure with combined transmission chart. Schott BG60 BG41 BG62 BG63 BG64 PDF. Data sheets with transmission charts. . A very good Schott IR-blocking glass is S8612. At the 700nm mark the IR supression is at a .01% level for a 1mm thickness. S8612 has a high UV and Visible transmission at a peak of 98%. Currently S8612 is the preferred choice for IR-blocking here on UVP. Schott S8612 PDF. Data sheet with transmission chart. The newest Schott IR-block glass is VG20, a green glass. At the 700nm mark the IR suppression is already at the 1E-04% level for a 1mm thickness. Schott VG20 PDF. Data sheet with transmission charts. . (2) Hoya C Series Color Compensating Filters Hoya Candeo is a Japanese manufacturer of optical products including filter glass and pre-mounted, circular filters. Their glass is used by many photographic filter manufacturers.The C Series glass is manufactured for use in digital devices to suppress IR contamination. The C types - C500S, E-CM500S, C5000, CM5000, CD5000 - all have similar transmission between 310-700nm reaching about 85-90% transmission of visible light between 400-550nm, then dropping to about 50% transmission between 600-620nm. The E-CM500S, with about 3% transmission at 700nm, appears to be the best at suppressing IR between 700-1100nm. Hoya Candeo Optronics Corp Company profile. Hoya Colored Glass Filters List. Hoya C Series Filters Transmission charts (combined) and technical data. FILTERS: UV/IR-BLOCK (Visible Pass) Listing order is alphabetical by company. Order does not imply preference. Just call them Visible bandpass filters. They are necessary if you want to use a full spectrum camera for Visible light shots or for UV-induced fluorescence in the Visible range. Small leakage on the UV side is not as troublesome to a Visible photo as IR leakage can be. Here is a good reference: UV/IR-Block & IR-Block Filters on a Converted Camera. {Add URL.} As stated there, the bottom line is that for accurate converted-camera visible colour under a UV/IR-block filter you must: pre-measure white balance in-camera against a white/grey card, and make a converter colour profile for your particular camera+lens+filter combination. . (1) Baader-Planetarium UV/IR-Cut Filter 2" #2459210A = Version A This filter transmits 410-680nm with the only IR bump way out there past 1200nm. Very minor UV leakage. It is considered one of the best UV/IR blocking filters. Cuts some blue between 400-410nm. Baader filters may be found at many astrophotography and astronomy retail/online shops as well as at Baader-Planetarium. ADDED 23 May 2023: The Baader UV/IR-Cut filter stacked with Schott BG 38 provides a slightly better color rendition by tapering the left (violet-blue) and right (red) shoulders. Some magentas, pinks and blue tones look better with this stack. Baader-Planetarium GmbH Home page in German. Baader-Planetarium GmbH Home page in English. Baader Filters Filter types with further links and search. Baader 2" UV/IR-Cut Filter (In German) (In English) General information on the "Sperrfilter" includes transmission chart. Baader 2" UV/IR-Cut Filter PDF. (In German) (In English) Baader UV/IR-Cut Spectral Analysis by Shane Elen. Scroll down. . (2) Astronomik UV/IR-Block Filter This is a filter made primarily for astronomical use. It transmits quite a lot of UV, so it would not be suitable as a UV/IR block filter when making UV-induced Visible fluorescence photos. It appears to block IR quite well. Astronomik Home page In German. Astronomik Home page In English. Astronomik UV-IR Blocker Scroll down for transmission chart. . (3) B+W 486 UV/IR-Block Filter This is an interference (dichroic) type filter. It has a 10% transmission toe at 700nm. Its left-hand shoulder transmits some UV between 360-400nm so it may not be suitable for UV-induced Visible fluorescence work. Schneider Kreuznach Home page of parent company. (In German) (In English) B+W Photo Filters General information. B+W Filter Types B+W 486 UV/IR Cut Filter In German only. Schneider Optics Home page of U.S. subsidiary of Schneider Kreuznach. B+W Filter Handbook PDF. B+W 486 is on page 27. Transmission chart is on page 61. . (4) Heliopan Digitalfilter #8025 UV/IR-Block Filter The filter transmits 325-710nm, so seems to allow UV and leak a little IR. It is probably not suitable for UV-induced Visible fluorescence work. Heliopan Home page. In German. Heliopan Filters for Digital Photography PDF. In English. Heliopan Digitalfilter #8025 Info and transmission chart. In German. . (5) Marumi UV-IR Cut UV/IR-Block Filter This filter transmits 400-700nm with a very, very sharp slope between 380-400nm and 675-710nm. There is the tiniest IR bump at 750nm and larger IR bump way out past 1075nm. Marumi Optical Co Home page. In Japanese. Marumi Digital Pro International page. In English. Marumi UV-IR Cut Filter Transmission chart on AstroArts website. . (6) Peca 700, 916, 918 UV/IR-Block Filters Peca offers three UV/IR blockers. Each transmits 400-700nm, but varies in how the near-IR and near-UV is handled. Evaluate the charts carefully to determine whether you will get the needed UV/IR suppression for your particular use. Peca Home page. Peca IR-UV Filters List. Peca 700 Transmission Chart The 700 filter reaches an 80% transmission of UV between 360-400nm. It transmits 80-90% IR between 700-725nm and leaks varying amounts of IR past 775nm with about 2.5% peaks. It must be stacked with IR-blocking glass. Peca 916 Transmission Chart The 916 cuts UV well but again it leaks 80-90% IR between 700-725nm and leaks varying amounts of IR past 775nm with about 2.5% peaks. So it must be stacked with IR-blocking glass. Peca 918 Transmission ChartThe 918 filter cuts some red in the 650-700nm range with about a 2% leak at 700nm and a minor bump around 850nm. It has minor UV leakage between 375-400nm.

Another Allamanda flower with a Violet Blue Cyan Green filter about 380nm to 530nm. For those interested, I have uploaded this file .X3F to DropBox, it is free. It is about 10mb. https://www.dropbox....20380-530nm.X3F It is a Sigma .x3f file from a Sigma DP1 compact camera. Because it is an original (older) Sigma compact some propriety photo editor programs will open it, BUT it is best to open it with the Sigma Photo Pro RAW converter, convert it to a .tiff file & work it that way. I am a novice at PP & only use Sigma Photo Pro, I have next to no experience with the other editors. Windows & Mac versions..... http://www.sigma-dp1.com/software/spp/ Straight out of Sigma DP1 full spectrum camera, with about a 380-530nm filter .JPG This is a astro 1.25inch filter so it is a circle on the sensor. Please excuse my hairy arms & legs, it is high summer in Queensland :) Good luck & please share your results. Cheers Col

Hi Everyone I have uploaded this file to DropBox, it is free. It is about 10mb. https://www.dropbox....%20Sunlight.X3F It is a Sigma .x3f file from a Sigma DP1 compact camera. Because it is an original (older) Sigma compact some propriety photo editor programs will open it, BUT it is best to open it with the Sigma Photo Pro RAW converter, convert it to a .tiff file & work it that way. I am a novice at PP & only use Sigma Photo Pro, I have next to no experience with the other editors. Windows & Mac versions..... http://www.sigma-dp1.com/software/spp/ I have some differently processed versions here too... I haven't cropped these, to show the issues I having with this camera with a wide lens & the 1.25inch AstroDon UVenus. The Sigma DP2 that I killed has a narrower field of view & I didn't have the reflection issues. I am looking for another DP2 to replace mine. Mono conversion Blue / Black conversion Custom WB Straight jpg covversion Good luck & please share your results. Cheers Col PS IMHO I strongly feel the pink / magenta cast is an artefact response of over-exposure, as the blue in it is clipped. Col

Does anyone have a Andrea U filter in 52mm ring to sell to me Please ? Cheers Col

Introduction It is a given that both the Baader-U and the Precision-U (old version) leak some small amounts of Visible and IR light. We already know from our experience of using both filters in our work that they both produce satisfactory UV photographs. So the primary purpose of this test is not to determine whether the filters leak, per se, but rather to get some practical information about using these filters. Equipment: Nikon D600-broadband + Nikon 105mm f4.5 UV-Nikkor The D600 was set to a Neutral [4,0,0,0,0] Picture Control and a particular white-balance preset to enable best judgement of proper exposure. For each shot I chose an exposure that kept my Lab Spheres 99% white standard from blowing out in the red or blue channel because I wanted to use the standard for white balance. This means that the UV exposures could probably be pushed a bit more if they did not contain this bright standard. The photos were converted in Photo Ninja using a D600 colour profile preset to present a standardized UV colour palette. Only minor tweaks were made to the endpoints of the histogram to the Black and White points. No other edits were applied. Please do not read too much into the exposure times. The afternoon light was very clear and steady, however I did have to move twice when a tree shadow began to encroach on my set-up. And outdoors, all exposures change with time. ********** Baseline Photographs The first photograph provides a baseline Visible image to illustrate the subject matter. The next two UV images give a UV baseline photo for each UV-Pass filter in full sunlight with no artificial UV illumination. Note that the UV signatures of both flowers were satisfactorily captured in each case. 1. The Subject: Rudbeckia hirta 'Denver Daisy' on left and Leucanthemum x superbum on right together with Color Checker Passport and Lab Spheres 99% Reflective Standard. 2. Baader-U: Filter used alone. The UV signature of the right-hand L. x superbum is very dark. Typically, I would further edit this photo to open up the shadows a bit in order to see more of the UV-dark details. 3. Precision-U(old): Filter used alone. The Precision-U(old) captures the UV pattern with slightly different false colours and slightly more open shadows. This is beneficial to seeing the very dark UV signature of the right-hand L. x superbum. ********** Trapping 'Pure' IR Leaks Past 800nm In the this experiment I stacked the Baader-U and then the Precision-U(old) with a B+W 093 pure IR-Pass filter to try to trap any IR leaks beyond 800nm in 15" and 30" exposures in full sunlight. The photos were white balanced against the Labsphere 99% standard, but no other edits were applied. The results of this experiment were interesting. The Baader-U seems to have some pure IR-leakage and the Precision-U(old) does not. To review, the Baader-U transmission chart shows tiny IR bumps between, approximately, 735-750nm, 800-825nm and 860-875nm. Kindly note: Long exposures like this are bound to trap even the smallest amount of leaked IR. Please Remember: For typical UV exposures under 4 seconds, this IR leakage is not significant enough to seriously contaminate the UV exposure. B+W 093 IR-Pass Filter: This is a pure IR-Pass filter beginning around 800nm and reaching 50% transmission at 830nm. It is equivalent to RG 830 glass or a Wratten 87C. Reference: Filter Handbook: B+W Filters, page 29. 4. Baader-U + B+W 093 IR-Pass Filter: 15" The Baader-U shows some IR leakage past 800nm in a 15" exposure. 5. Baader-U + B+W 093 IR-Pass Filter: 30" Compare this Baader-U 30" exposure to the next Precision-U(old) 30" exposure - very interesting. 6. Precision-U(old) + B+W 093 IR-Pass Filter: 30" There is some contamination on the top and left but there is definitely not any IR leakage past 800nm from the Precision-U(old). EDIT: We are not sure of the source of the IR leakage in this photo. I have speculated that it might be from the D600 IR shutter monitor or from my filter step-ring fittings. ********** Trapping Red/IR Leaks Past 695nm In this experiment I stacked each of the UV-Pass Filters with a Red + IR-Pass filter, the B+W 092, to try to trap any near-IR leaks beyond 695nm in 15" and 30" exposures in full sunlight. I then compare the results to the previous experiment. The photos were white balanced against the Labsphere 99% standard, but no other edits were applied. Again, the results were interesting. Both the Baader-U and the Precision-U(old) show leakage under the 092, with the Baader-U leakage being somewhat less. There are also colour differences between the filters after white balance. I don't know what that signifies, if anything, because false colours are at play here. To review, the Baader-U transmission chart shows tiny IR bumps between, approximately, 735-750nm, 800-825nm and 860-875nm. Kindly note: Long exposures like this are bound to trap even the smallest amount of leaked IR. Please Remember: For typical UV exposures under 4 seconds, this IR leakage is not significant enough to seriously contaminate the UV exposure. B+W 092 IR-Pass Filter: This is a Red + IR-Pass filter beginning at about 650nm and reaching 50% transmission at 695nm. It is equivalent to RG 695 glass or a Wratten 89B. Reference: Filter Handbook: B+W Filters, page 29. 7. Baader-U + B+W 092 IR-Pass Filter: 15" There is obvious leakage by the Baader-U under the 092. Is it Red leakage or IR leakage, or both? I don't know. Let's just call it 'near-IR' leakage. After the white balance step, the photo shows some blue false colour. 8. Baader-U + B+W 092 IR-Pass Filter: 30" Interestingly, the amount of the Baader-U's near-IR leakage under the 092 does not increase as much as I thought it would with a doubled exposure time. 9. Precision-U(old) + B+W 093 IR-Pass Filter: 15" Compare this to the first Baader-U 092 15" photo to see that the Precision-U(old) has slightly stronger near-IR leakage. Again, I don't know if this is Red leakage or IR leakage, or both. Most likely, the near-IR leakage of the Precision-U(old) is in a different portion of the near-IR waveband from the Baader-U. ********** IR Leakage Test Conclusion I would say that in these long 15" and 30" exposures, the Baader-U has wider overall IR-leakage than the Precision-U(old) and that the Precision-U(old) has slightly stronger near-IR leakage than the Baader-U. Again I feel that I should remind you: we know from extensive experience that for purposes of UV documentary photographs, both filters satisfactorily capture UV signatures. Because of slightly different UV transmission and minor colour differences, editing will be different for work produced with each filter with respect to white balancing, opening up shadows or other such tasks. ********** Controlling IR Leakage in Both Filters (if you feel you really must...) If you stack BG39 or S8612 filter glass with either your Baader-U or Precision-U(old), then the minor IR leakage they have is cut even further in spite of the fact that the both supplementary filters also pass some IR. 10. S8612 UV/Vis-Pass Filter: This is a blue-green filter which passes UV and Visible wavelengths and which can serve an IR-block. The S8612 glass is very similar to BG39 glass. Note that both these BG filters do pass some IR. Here is a transmission chart from Schott's optical filter catalogue: Schott: Glass Made of Ideas, 2009. I darkened the graph along the 1% line to make it more obvious. At 700nm both filters go below a 1% transmission of IR. 11. Baader-U + S8612 + B+W 092: 30" This long exposure shows no IR leakage. 12. Precision-U(old) + S8612 + B+W 092: 30" This long exposure shows no IR leakage. 13. UV Photograph with Baader-U + S8612 Here is the Baader-U UV photograph with additional IR blocking. There is not much change from the first Baader-U UV photograph (#2 above). 14. UV Photograph with Precision-U(old)+ S8612 Here is the Precision-U(old) UV photograph with additional IR blocking. There is some colour shift from the first Precision-U UV photograph (#3 above). ********** Trapping IR Leaks in IR-only Illumination I had wanted to try to show, as per Bjørn's suggestion below, that repeating the IR leakage tests in IR-only illumination would yield similar results to the IR leakage tests made in full sunlight. It appears as though this is true, but I'm having trouble determining whether I have "pure enough" IR illumination using my little IR-LED hotshoe light. Also, this IR LED light source - even when combined with some light from an (impure) Incandescent light bulb - does not seem strong enough to boost exposure times above 30 seconds. So I'm going figure out how I can set this experiment up better before I post anything here.

Hello, Ladies and Gentlemen. This is my first post here at Ultraviolet Photography. I have spent a lot of time reading through all of the various posts available already, and I am impressed by the amount of information available on this forum. However, I still have some additional questions (and, being more of an artistic personality than a scientific one, I am having difficulty coming to certain conclusions). Here it goes: I am just starting out in the world of UV Photography. As I stated in my introductory post here, I am interested in creating UV Portraits. However, as I am new, I am starting slowly. With that in mind, I have purchased some equipment that I think should help me get into the world of UV photography, but I don't seem to be quite there yet. I have had a company called LifePixel convert my Canon 20D into [what is known on this website as] a "broad-spectrum" camera (they call it a full-spectrum camera). This is my only camera body capable of capturing any type of UV light. I have also gone out and purchased (used on eBay) an El-Nikkor 50mm f/2.8 enlarger lens and an adapter ring (M39 thread mount to Canon EOS) and bellows to fit the lens to my camera body. Additionally, I have also purchased (again, used on eBay) a B+W 403 UV Pass filter and a Tiffen Standard Hot Mirror filter. I realize that the B+W 403 filter does leak some infrared. I also realize that the Hot Mirror filter also leaks some infrared. My hope was, with the two of them together, I'd be able to cut enough of the infrared to not have to worry about contamination, but I'm beginning to think this is not the case. I don't yet have the funds available to purchase the coveted Baader Venus U (it is on my list, however). Does anyone have any other suggestions of a less-expensive way to go to begin capturing RAW UV images? Perhaps a different IR Cut filter that I don't know about yet? I have scoped out the filter section, but a lot of what I see there have dead links or refer to glass types that, when Googled, seem to lead me nowhere. I do have two additional questions (which, perhaps, should be in a separate post - please let me know if I should make that correction): 1. Do flowers need to be "alive" in order to reflect UV light? There is often quite a bit of wind where I live, so picking a flower and bringing it indoors to photograph is helpful, though I'm sure there is far less UV light indoors, so I have a conundrum there. 2. I have Capture One for my white balancing (as we all no ACR doesn't work very well in the non-visible spectrum). Is there a certain color temperature I should be aiming for in my UV photographs (once I finally achieve them)? This is a JPG of the RAW capture before any white balance. This was taken in mid-morning sunlight on a boat dock above water (I'm sure there was some reflectivity). She is holding a MacBeth Color Checker Chart (as well you know). It was shot with the B+W 403 stacked with the Tiffen Hot Mirror. I wasn't sure if including the image would help troubleshooting at all. I assume I'm still seeing quite a bit of IR leak. Thanks again for any advice. Ahr Neely

With the D600-broadband and a Nikon 105mm f/4.5 UV-Nikkor, I photographed, in sunlight, a Color Checker Passport, a small Melampodium paludosum flower and three Labsphere Reflectance Standards (99, 75, 50) using four UV-Pass filter options. Baader-U Precision-U: the older version Hoya 340 + S8612(1.75mm) Hoya 360 + S8612(1.75mm) The NEFs were converted in Photo Ninja. White balance was set on the top white Labsphere 99 Standard. For saturation and contrast, the Scenic option was chosen. This corresponds approximately to a Nikon Picture Control of Standard with perhaps a +1 for contrast and saturation. For colour accuracy, a Photo Ninja D600 profile made with the Color Checker Passport was applied. Minor tweaks were made for white point, black point and highlight control. Some dust bunnies were removed in Capture NX2. The standard curve applied during demosaicing was left untouched. Therefore the reflectance standards are not accurately reproduced with respect to brightness. If the curve were adjusted to reflect the actual brightness, then the photo would appear too dark. The flower is out of focus. The purpose of the experiment was to see what the differences are between the four photos made with the listed UV-Pass filters after the resulting photos have been both colour- and white-balanced. Apparently, for these particular subjects, there is not much difference once colour and white are standardized. However, for other subjects, you might see some variations in the presence of green or intensity of yellow. And the intensity of violet or blue shades might vary somewhat for any subjects. I will try to repeat this test with some floral subjects to see if I can show more about these minor differences. Baader-U f/11 for 1/8" @ ISO 400 Precision-U(old) f/11 for 1/5" @ ISO 400 Hoya 340 + S8612 f/11 for 1/6" @ ISO 400 Hoya 360 + S8612 f/11 for 1/6" @ ISO 400

I tested four UV-Pass filter options. This is different from the test of 4 filter options I ran recently and posted on Nikongear.com. The subject was one of our classic UV-bullseye flowers - a Rudbeckia. These are grocery store Rudbeckias, so I don't know their genus/species although it is probably an R. hirta. All fotos were converted in Photo Ninja using a D600 colour profile preset I created. For the UV fotos: White Balance was made on the same area of the photos. It isn't an exact science so you might reach other conclusions on the WB if you were doing it yourself. "-) The Exposure, Highlights and Black sliders were applied as needed to adjust the histogram ends. This is primarily about setting the black & white points. The Shadow slider was used as needed to lift the shadows a bit because the fotos were made in strong contrasty sunlight to gain maximum UV. The Details slider was applied at the default 15 because it is awesome. Default Photo Ninja sharpening and noise reduction were used. Saturation was kept moderate. In my typical workflow, after conversion in PN, these UV fotos would move to an editor for local edits dealing with shadows/highlights and refinement of sharpening and so forth. But not today. This is enough to make the point that there are multiple options available for UV-Pass filters. Equipment: D600-broadband + 105/4.5 UV-Nikkor + UV-Pass Filters + Sunshine All fotos shot at f/11 and ISO 400. Exposure times varied a bit because there were some clouds playing around with me so we will just ignore exp times. Some other day in non-changing light I might try to make a call as to which filter is "faster". The key thing to note is that while there may be some variations in False Colour, each filter does record the UV signature of these Rudbeckias. [1] B+W 403 & S8612 (1.75mm thick) [2] B+W 403 & B+W BG39 [3] Precision-U: Old Version [4] Baader-U

While I was outdoors broiling the D600 and some filters in this intense summer heat, I also grabbed a shot with my tiny little 340AF15 bought off the internet. Had to handhold it to the UV-Nikkor, but didn't do too well at that. You can see the Light Leak in the lower left quadrant. I think the filter is deteriorating a bit. One side seems to be becoming filmy. It wouldn't clean up. Or perhaps this filter is layered and the humidity got to it out there in Swamplandia. I just don't know. It's not a good shot. However, the photograph, while obviously deficient, does at least serve to show there is UV-signature capturable 25nm below where our filters normally peak. And, it doesn't look all that much different from what we normally shoot with a Baader U. D600-broadband + 105/4.5 UV-Nikkor + 340AF15 + Sunshine f/11 for 6" @ ISO 400. This needed a long exposure time !! Today the same shot with the Baader U need only 1 second. (And that is actually a little big long, but I had some other variables at play today - location, clouds and so forth.)

This is one of my first images with my new D300 broad band, using a Precision U filter in front of a UV-Nikkor 105mm. Shot near Sønderled in Norway, wet spring forest, the remains of an old rusty chassis. WB adjusted in Capture One Pro. The D300 is now modified with the Precision U filter replacing the internal filter pack and shaker filter.