Andrea B. Posted May 18, 2018 Share Posted May 18, 2018 Editor's Note: To avoid persistent HTML formatting problems in the first post of this topic, at Dmitry's suggestion, I have transferred his topic here to my name so that I can help with the editing. This forum software does not seem to permit a member to have full HTML privileges. Similar Experiment by Colinbm: http://www.ultraviol...__fromsearch__1 http://www.ultraviol...ch__1#entry1640 http://www.ultraviol...ch__1#entry1826 Lens Spectra with Jeweler's Spectroscope by Dmitry K. Goal: To test and compare lenses for UV-capability using photographs of the solar spectrum made through a jeweler's grated prism spectroscope. Filters are used to reveal the UV and IR areas of the spectrum while hiding the Visible portion. The Fraunhofer lines can be seen for estimation of wavelengths. This topic will contain an index and short summary for each tested lens. Comments and discussion about the methodology is welcome here. Comments about specific lenses should be made in the link lens topic. Spectroscope: Jeweler's grated prism spectroscope from China (about $30). Example LINK. Spectroscope and camera assembly Filters Filter Thickness Equivalence ZWB1 2 mm U-340, UG11 ZWB2 2 mm U-360, UG1 ZWB3 2 mm U-330, UG5 QB21 2 mm BG38 Camera: Olympus E-PM1 full spectrum conversion. I converted the E-PM1 myself. The internal blocking filter was not replaced with clear glass. The sensor assembly was adjusted using thin shims between the case and assembly. The original internal blocking filter is about 2.6mm thick (dimensions: 2.6 x 17.3 x 22.3 mm). The shims are 0.6 mm on average. So without replacement glass I needed to move the sensor plane about 0.7 mm (or 0.9 mm ?). Therefore I omitted the reinstallation of the shims which leaves a 0.1 mm distance increase in the flange focal distance. For native AF lenses this is acceptable. For adapted lenses I use a shortened adapter to reach infinity focus. Lens List For all lenses spectral tests were made in sunlight. For some lenses an additional spectral test was made using a mercury (Hg) arc lamp. The approximate reach was estimated using the results found here. Any lens reaching below 370 nm is given a 'yes'. A lens reaching 370-375 nm is labeled as 'ok'. If the lens cannot reach below 380 nm, then it is given a 'NO'. Brand Type & Solar Link Hg Lamp Link Focal Length Speed Mount AF/Man OK for UV? Focus Shift Reach Est Helios 44M-4 58 mm f/2.0 M42 man Yes 360-370nm Industar 50-2 link 50 mm f/3.5 M39 M42 man Yes 360-370nm Industar 26m 50 mm f/2.8 M39 man Yes 350-360nm Industar 61LD 53 mm f/2.8 M39 M42 man Yes 365-375nm Jupiter-3 Юпитер-3 3 50 mm f/1.5 M39 man Yes 355-360nm Lomo T-43 link 40 mm f/4.0 custom man Yes 330-360nm Meike aka Kaxinda Neewer 28 mm f/2.8 MFT APS-C man Yes yes 360-370nm MIR МИР 1B 37 mm f/2.8 M42 man ok 370-375nm Olympus M. Zuiko Digital 12 mm f/2.0 MFT AF ok 375-385nm Olympus M. Zuiko Pro 12-40 mm f/2.8 MFT AF NO 385-390nm Olympus M. Zuiko EZ 12-50 mm f/3.5-6.3 MFT AF ok 375-385nm Olympus M. Zuiko EZ link 14-42 mm f/3.5-5.6 MFT AF ok 365-375nm Olympus M. Zuiko II R 14-42 mm f/3.5-5.6 MFT AF ok 370-375nm Olympus M. Zuiko Digital 17 mm f/1.8 MFT AF ok yes 370-375nm Olympus M.Zuiko Digital link 25 mm f/1.8 MFT AF ok yes 370-375nm Olympus M.Zuiko Digital 45 mm f/1.8 MFT AF ok 370-375nm Olympus M.Zuiko Digital Macro 60 mm f/2.8 MFT AF NO 385-390nm Panasonic Lumix G Vario 12-32 mm f/3.5-5.6 MFT AF NO 390-395nm Panasonic Lumix G 14 mm f/2.5 MFT AF Yes yes 360-370nm Panasonic Lumix G Vario 14-42 mm f/3.5-5.6 MFT AF ok 375-385 nm Petzval link 85 mm f/2.2 Canon Nikon etc man Yes 355-360 nm Sigma EX DN 30 mm f/2.8 MFT APS-C AF Yes 360-370 nm SLR Magic Hyperprime Cine 25 mm T0.95 MFT man ok 375-385 nm Link to comment
Dmitry Posted May 18, 2018 Share Posted May 18, 2018 Spectrum does contain UV part of second-order spectrum on right side overlapping IR part. Wavelengths are guessed, based on this topic spectrum labels. Brand Type & Solar Link FL Speed Mount AF/Man OK UV? FShift Reach Est Helios 44M-4 58 mm f/2.0 M42 man Yes 360-370nm Industar 50-2 50 mm f/3.5 M39 M42 man Yes 360-370nm Industar 61LD 53 mm f/2.8 M39 M42 man Yes 365-375nm Lomo T-43 40 mm f/4.0 custom man Yes 330-360nm Meike/Kaxinda/Neewer 28 mm f/2.8 MFT APS-C man Yes yes 360-370nm MIR/МИР 1B 37 mm f/2.8 M42 man ok 370-375nm Olympus M.Zuiko Digital 12 mm f/2.0 MFT AF ok 375-385nm Olympus M.Zuiko Pro 12-40 mm f/2.8 MFT AF NO 385-390nm Olympus M.Zuiko EZ 12-50 mm f/3.5-6.3 MFT AF ok 375-385nm Olympus M.Zuiko EZ 14-42 mm f/3.5-5.6 MFT AF ok 370-375nm Olympus M.Zuiko II R 14-42 mm f/3.5-5.6 MFT AF ok 370-375nm Olympus M.Zuiko Digital 17 mm f/1.8 MFT AF ok yes 370-375nm Olympus M.Zuiko Digital 25 mm f/1.8 MFT AF ok yes 370-375nm Olympus M.Zuiko Digital 45 mm f/1.8 MFT AF ok 370-375nm Olympus M.Zuiko Macro 60 mm f/2.8 MFT AF NO 385-390nm Panasonic Lumix G Vario 12-32 mm f/3.5-5.6 MFT AF NO 390-395nm Panasonic Lumix G 14 mm f/2.5 MFT AF Yes yes 360-370nm Panasonic Lumix G Vario 14-42 mm f/3.5-5.6 MFT AF ok yes 375-385nm SLR Magic Hyperprime Cine 25 mm T0.95 MFT man ok 375-385nm Sigma EX DN 30 mm f/2.8 MFT APS-C AF Yes 360-370nm Pending updates to table Link to comment
dabateman Posted May 19, 2018 Share Posted May 19, 2018 I think you are using a prism spectroscope which is why your images look different than I am used to. This may be fine for uv detection, as they tend to spread to shorter wavelengths and compress the larger ones. Link to comment
Dmitry Posted May 19, 2018 Share Posted May 19, 2018 I seen scheme of this spectroscope. It does have both prism and grating. Prism is to line up things to compact cylinder. Single prism never give second-order spectrum. Link to comment
Andrea B. Posted May 24, 2018 Author Share Posted May 24, 2018 Dmitry - Thank you for all this work and the index !!I am eager to get one of the jeweler's spectro loupes and try this myself. :) Link to comment
Dmitry Posted May 24, 2018 Share Posted May 24, 2018 Trying my best :) Cloudy week, had few minutes to catch sun before sunset.If someone want to use 12-40pro for UV and have large filter, its possible to use on not modified Olympus body without loss of UV range.I think its 380+ nm Link to comment
colinbm Posted June 2, 2018 Share Posted June 2, 2018 Hi Dmitry K " Spectroscope usedJewelry spectroscope from China (about $30). " Where can we see what this is please ? CheersCol Link to comment
Dmitry Posted June 2, 2018 Share Posted June 2, 2018 Posted photo of assembly here. You may search for "gem spectroscope" or "diffraction spectroscope" on aliexpress or ebay. Link to comment
colinbm Posted June 2, 2018 Share Posted June 2, 2018 Thanks Dmitry KYes it is a diffraction grating spectroscope.The wavelength scale across the image is quite linear.CheersCol Link to comment
Dmitry Posted June 2, 2018 Share Posted June 2, 2018 Yes, it is. You may notice magnified second order spectrum on right side on some of images. Its not possible on prism only spectroscope. Link to comment
colinbm Posted June 2, 2018 Share Posted June 2, 2018 Yes that is the problem with the diffraction grating, the second order overlapping the first :-(I have found that the Amici Prism spectroscopes are very suited for UV research, as the UV scale is expanded compared to the IR scale. Link to comment
Dmitry Posted June 16, 2018 Share Posted June 16, 2018 New test with Hg lampsLomo T-43Olympus 25/1.8Industar-50-2 334nm not visible on both lenses, but Olympus lens can reach 365nm!Reference link - http://zeiss-campus....mercuryarc.html Link to comment
Dmitry Posted July 1, 2018 Share Posted July 1, 2018 Got Kaxinda/Meike/Neewer 28mm f2.8 myself and did quick test manual focusreach est 360-370nmMounts - MFT, APS-C sized others (Sony E, Nikon 1,Canon EOS M,Fujifilm X)focus shift - yes Link to comment
Dmitry Posted July 10, 2018 Share Posted July 10, 2018 Since July 7 my e-pm1 is tuned for infinity. Worked with a file for a while. B) Link to comment
Dmitry Posted July 11, 2018 Share Posted July 11, 2018 Found Olympus 14-42mm II R cheap and huge kit lens and tested it.It have nearly same 370-375nm range like compact pancake EZ version. Link to comment
Dmitry Posted July 17, 2018 Share Posted July 17, 2018 Got few minutes to test friend's Lumix 14-42mm kit lensReach is around 375-385nm Link to comment
Andrea B. Posted July 21, 2018 Author Share Posted July 21, 2018 Dmitry, it would be interesting to see UV scenes made with each lens when you get the time to set up some kind of comparative test. For example, how would a photo made with the Meike 28mm lens compare to the same subject shot using a 28mm setting on the Lumix 14-42mm lens which is less UV-capable? Link to comment
Dmitry Posted July 21, 2018 Share Posted July 21, 2018 Andrea, its interesting task, but I need idea about scene, filters and lenses :) I can't take everything with me, can you please list most interesting lenses?Oh, waiting for portable UV-tube lamp to arrive for more testing and as light source for scenes at home. Link to comment
Dmitry Posted July 21, 2018 Share Posted July 21, 2018 4 more lenses Helios-44M-4M42 mountmanualreach 360-370nm Mir-1BM42 mountmanualreach 370-375nm Olympus 60mm MacroMFTAFreach 385-390nm Olympus 12mmMFTAFreach 375-385nm Link to Lumix 14-42 is incorrect Link to comment
Dmitry Posted July 21, 2018 Share Posted July 21, 2018 Its all lenses I have with filter threads 52mm or smaller :D Link to comment
Andrea B. Posted July 22, 2018 Author Share Posted July 22, 2018 Dmitry, sorry about the bad link !! I did a copy/paste but forgot it included an old link. Your updates are scheduled for this evening. Link to comment
Dmitry Posted August 1, 2018 Share Posted August 1, 2018 One more lens tested, glass monster :) SLR Magic 25mm T0.95 (note it have T-number, not f-number)MFTmanualreach 375-385nm Link to comment
aphalo Posted October 9, 2018 Share Posted October 9, 2018 Hi Dimitry, Andy, Michael, Andrea, et al., A couple of weeks ago I did some measurements of my objectives using an Ocean Optics Maya 2000Pro spectrometer and the Godox AD200 flash with the bare lamp recommended by Enrico as light source. I had not seen this thread until today. I estimated wavelengths at -3 EV compared to the average of the central part of the visible band (430-660 nm). Some of the objectives are the same as measured by Dimitry and with data in the table at the top of this thread computed with Andy's MATLAB script. My measurements are: M.Zuiko 12-50 mm, 376 nm; M.Zuiko 25 mm, 372 nm, M.Zuiko 45 mm, 371 nm, M.Zuiko 60 mm Macro, 388 nm. So, agreement is almost perfect! I guess we can conclude that both approaches are reliable, with this not-planned but useful cross-validation. :) :) As an aside, the Sigma 30 mm f:2.8 DN A 013 in MFT mount reaches 356 nm at -3 EV and 369 nm at -1 EV, so this explains why it works nicely in UV. Link to comment
Andrea B. Posted October 9, 2018 Author Share Posted October 9, 2018 Pedro, thanks for this very interesting confirmation. It's great to hear that Dmitry's jeweler's spectroscope method provides an excellent estimate for UV lens transmission. At Dmitry's suggestion I have transferred this topic to my name in order to avoid the HTML formatting problems we have periodically experienced. I'll add a note to the first post to clarify this. Link to comment
colinbm Posted October 10, 2018 Share Posted October 10, 2018 Hi Pedro, is this a recently made lens ? Link to comment
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