colinbm Posted July 5, 2020 Share Posted July 5, 2020 First up is todays Sun spectrum for comparison, goes down to 321nm. Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Igoriginal refurbished lens, 35mm f3.5, Soligor III, goes down to 336nm. attachment=19563:20200705 Igoriginal 35mm f3.5 Soligor III lens.jpg] Link to comment
Andy Perrin Posted July 5, 2020 Share Posted July 5, 2020 Amazing how Igoriginal can make the sun stronger than without the lens... (You should probably normalize these somehow?) Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Andy I am new to this, can you explain please ? Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Steinheil Munchen Cassar S 50mm f2.8 lens, goes down to 340.5nm. Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Novoflex Noflexar 35mm f3.5 lens, goes down to 345nm. Link to comment
Andy Perrin Posted July 5, 2020 Share Posted July 5, 2020 If you look at the peaks of the graphs, all those graphs have different peaks, and all are HIGHER than the case with no lens in the system (probably the lens is concentrating the light?). Anyway, point is that you can't compare one graph to another to see where it drops off if all the peaks are at different heights. So I'm suggesting that you normalize (divide by) the height of the maximum value so that all the graphs will be comparable. E.g. Divide the Cassar by 0.161, the Noflexar by 0.069, etc. Then you can plot them on top of each other to see what is going on. Link to comment
Cadmium Posted July 5, 2020 Share Posted July 5, 2020 http://www.optimumopt.com/?mod=product&col_key=product&cate_id=49&pro_id=42&t=prodetail&lang=en Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Sigma 30mm f2.8 Art lens, goes down to 360nm. Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 If you look at the peaks of the graphs, all those graphs have different peaks, and all are HIGHER than the case with no lens in the system (probably the lens is concentrating the light?). Anyway, point is that you can't compare one graph to another to see where it drops off if all the peaks are at different heights. So I'm suggesting that you normalize (divide by) the height of the maximum value so that all the graphs will be comparable. E.g. Divide the Cassar by 0.161, the Noflexar by 0.069, etc. Then you can plot them on top of each other to see what is going on. Thanks AndyI think I can see what you mean, I don't know how to change this.Does it make any difference to the lowest UV transmittance results ?CheersCol Link to comment
Andy Perrin Posted July 5, 2020 Share Posted July 5, 2020 Not sure, your device seems to cut off at 350, and with all peaks at different values, it's hard to judge the lens by just looking where it goes to zero. Can you export the data to Excel and just do it there? Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Not sure, your device seems to cut off at 350, and with all peaks at different values, it's hard to judge the lens by just looking where it goes to zero. Can you export the data to Excel and just do it there? Andy the device is supposed to be capable of down to 250nm, I don't have any UV lamps that go this low to check this.The sunlight measured goes down to 321nm today.I will need to learn this business of exporting the data to Excel & making the adjustments & re-displaying them. I am not a scientist or come from a science background.CheersCol Link to comment
Andy Perrin Posted July 5, 2020 Share Posted July 5, 2020 Look also for the option to export to .CSV because Excel can open those. You don't need any math more fancy than division so it shouldn't be too bad. Link to comment
Cadmium Posted July 5, 2020 Share Posted July 5, 2020 They are going nuts outside with fireworks here right about now, not my favorite thing anymore.His sunlight scan goes down to 325nm. His UV Illuminance Spectrophotometer SRI-2000UV goes down to 250-850nm. SRI-2000+, wavelength from 350-950nm, not sure which.There are 4 ranges/models available I think. Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 An oddie, O D Industries 50mm f4.5 lens, goes down to 341.5nm. Link to comment
Cadmium Posted July 5, 2020 Share Posted July 5, 2020 UV Illuminance Spectrophotometer SRI-2000UVFancy little piece of equipment. Link to comment
ulf Posted July 5, 2020 Share Posted July 5, 2020 Amazing how Igoriginal can make the sun stronger than without the lens... (You should probably normalise these somehow?)Any magnifier can do that, locally.A camera lens is normally acting like a very advanced magnifier.Then the intensity at ground level can also vary quite a bit due to atmospheric disturbances. Link to comment
Stefano Posted July 5, 2020 Share Posted July 5, 2020 To avoid this, you should use a PTFE tile instead of the Sun as your light source. Link to comment
ulf Posted July 5, 2020 Share Posted July 5, 2020 The UV Illuminance Spectrophotometer SRI-2000UV is a specialised tool for analysing light sources like lamps and LED panels. To get proper transmission measurements with reasonable accuracy will be tricky and need some other light source than the sun.The math is simple and can easily be st up in an Excel sheet, but the opto-mechanical design of the device is not well suited for such measurements. Link to comment
ulf Posted July 5, 2020 Share Posted July 5, 2020 To avoid this, you should use a PTFE tile instead of the Sun as your light source. A PTFE tile radiate very little light by it self and will disintegrate before it become a meaningful light-source, even in the visual range. Link to comment
ulf Posted July 5, 2020 Share Posted July 5, 2020 For transmission measurements in the UV-region light-sources with deuteriuml-lamps or continuous short arc xenon lamps are used.https://en.wikipedia.org/wiki/Deuterium_arc_lamphttps://en.wikipedia.org/wiki/Xenon_arc_lamp Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Thanks UlfI am looking for suitable lamps. Link to comment
ulf Posted July 5, 2020 Share Posted July 5, 2020 Be VERY careful!!! Those lamps can be very dangerous, in several different ways!!!High voltages and temperatures, strong UV, including UV-C, High pressure and risk of explosions are some of the risks. It is NOT well suited for any DIY. Link to comment
colinbm Posted July 5, 2020 Author Share Posted July 5, 2020 Yes thanks Alf, I would like lamps that have a housing. Link to comment
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