Andrea B. Posted May 3, 2015 Share Posted May 3, 2015 EDITOR'S NOTE: 2021 December 10. This AndreaU UV-pass filter was an earlier version which is no longer sold. I like the AndreaU - and not just because it shares my name! This UV-pass filter is robust against IR under typical UV exposures in strong sunlight. And and it can be used artistically for interesting false colours by setting an in-camera white balance or by making converter/editor tweaks. Under good strong sunlight, I found no particular benefit to stacking the AndreaU with an IR-blocker like the S8612. FWIW, the UV index was at 8-9 while I was shooting according to my weather app. With any of our UV-pass filters is always useful to keep an IR-blocker handy for longer exposures or exposures under certain artificial UV illumination that might also be outputting some visible or IR light too. I did find minor false colour changes with using the S8612 over the AndreaU. In the technical stacked filter tests, I needed long exposures to push any leaked light through the stacks. I decided, somewhat arbitrarily, to show you the set of 10 second exposures and one 5 second frame. Light may leak through sooner - or later - than that depending on the strength of the illumination in the scene. I don't know whether there is a solid way to pin that down. But the point should be made that it is not particularly easy to leak a lot of visible or IR light through the AndreaU. Equipment: UV-Nikkor 105/4.5 + D600-broadband + Sunlight Reference Fotos Dandelion for its classical UV-absorbing bullseye and false yellows. CC Passport for its false blues. Visible dandelion and BaaderU dandelion for comparisons. Baader UVIR-Cut Visible BaaderU UV-Pass Profiled false colour and white balance. AndreaU UV-Pass Profiled false colour and white balance. There is a bit of green tint in the bullseye. AndreaU UV-Pass Raw composite made in Raw Digger. AndreaU UV-Pass An in-camera white balance which gives some pretty magenta/violet false colours. AndreaU UV-Pass The CC Passport in profiled false colour and white balance. Stack: AndreaU UV-Pass + S8612 IR-Cut To test whether AndreaU benefits from additional IR-blocking. Profiled false colour and white balance. There are only minor false colour changes - less green than in the preceding set. Stack: AndreaU UV-Pass + S8612 IR-Cut Raw composite made in Raw Digger. Stack: AndreaU UV-Pass + S8612 IR-Cut An in-camera white balance. Stack: AndreaU + S8612 IR-Cut The CC Passport in profiled false colour and white balance. Technical Tests Even though the AndreaU does not particularly benefit from the addition of an IR-blocker during normal exposures in strong sunlight, it is important to test for the types of leakage which can be "pushed" through the filter. I stacked the AndreaU with some other filters and made fotos of my Labsphere reflective standards set. Only the fotos of the 99% white standard are shown here. The exposures were 10 seconds long with the exception of the visible test which was 5 seconds long. We know the AndreaU passes a very small amount of visible violet and violet-blue wavelengths so a shorter exposure length is not unexpected for that test. With certain white balance settings some violet/blue can be brought out in UV shots for a very pretty effect. These fotos are all raw composities made in Raw Digger unless otherwise noted. Following each foto is a histogram made from sampling as large an area as possible inside the Labsphere circle. These reading are not absolute, of course. They are only valid for the light in which I was working while shooting. But they do serve to indicate in which channels visible or IR light leakage might be recorded. A range from -4 EV to +2 EV was chosen with a bin of 1/96 EV in size except for the very last IR test which only started to record at -6 EV. AndreaU UV-Pass Raw composite. Histogram. Stack: AndreaU + S8612 IR-Cut To test whether AndreaU benefits from additional IR-blocking. Almost the same as the preceding set. Raw composite. Histogram. Stack: AndreaU + Baader UVIR-Cut To test for Visible leak. Exposure is pushed to 5 seconds. Violet and/or blue light has been recorded. This is known from the AndreaU's transmission chart. Raw composite. Histogram. Stack: AndreaU + GG420 UV-Cut Completely cut UV and see what happens. Exposure pushed to 10 seconds. Red and/or IR may have been recorded. Note that to prevent UV-induced visible fluorescence from contaminating the photo, stack the GG420 on top of the UV-pass filter. Raw composite. Histogram. Stack: AndreaU + 092 Red+IR-Pass To test for Red or IR leak. Exposure pushed to 10 seconds. Red and/or IR may have been recorded. Raw composite. Histogram. Stack: AndreaU + 093 IR-Pass To test for IR leak. Exposure pushed to 10 seconds. Almost nothing has been recorded. Raw composite. The out-of-camera shot was black. Histogram. Link to comment
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