Then what is the explanation? Is in the increase filtering between 380-400nm? Is there cumulative effect, where the filter and stack together are additive in nature? Could it be just my cameras? Is there some fluorescence in these lenses? Or with certain wavelengths the lenses are skewing the wavelengths towards the edges and corners?
Is your test average this across the whole frame or sampling a portion? This curve is exactly the same in the center and at the edges and corners, with no deviation, including with a lens mounted where ray angle may come into play more?
I'll revise my post and soften my comments around the "why". I will say "no one knows" from now on, that seems to be the safest bet.
My last question would be, based on your test, do you feel there should be as noticeable change between bare lens and Kenko filtered lens photos? In other words, is your test confirmed in the test shots I have posted and vice versa?
Here is more info about the Lensrentals test for the Zeiss filter graph I posted:
I only mentioned the manufacturer posted transmission graphs and the Lensrentals one. If the Lensrentals test isn't transparent enough in how the test was done, I guess we have to ignore their test.
realVivek wrote:
Tim, I do not agree with the speculation that there is some edge/corner leakage of the Sony filter stack. I already posted that in reply to inks&paper. The Sony stacks are virtually indistinguishable from that of a Kenko Zeta L41 filter when it comes to UV cutoff.
I used a calibrated Ocean optics spectrometer with a cosine corrector for my measurements. There are no details from the other reported measurements.
The STC595 in that graph refers to a STC drop in filter (meant to be used with a full spectrum camera).
Then what is the explanation? Is in the increase filtering between 380-400nm? Is there cumulative effect, where the filter and stack together are additive in nature? Could it be just my cameras? Is there some fluorescence in these lenses?
Is your test average this across the whole frame or sampling a portion? This curve is exactly the same in the center and at the edges and corners, with no deviation, including with a lens mounted where ray angle may come into play more?
I'll revise my post and soften my comments around the "why". I will say "no one knows" from now on, that seems to be the safest bet.
My last question would be, based on your test, do you feel there should be as noticeable change between bare lens and Kenko filtered lens photos? In other words, is your test confirmed in the test shots I have posted and vice versa?
Here is more info about the Lensrentals test for the Zeiss filter graph I posted:
I only mentioned the manufacturer posted transmission graphs and the Lensrentals one. If the Lensrentals test isn't transparent enough in how the test was done, I guess we have to ignore their test.
realVivek wrote:
Tim, I do not agree with the speculation that there is some edge/corner leakage of the Sony filter stack. I already posted that in reply to inks&paper. The Sony stacks are virtually indistinguishable from that of a Kenko Zeta L41 filter when it comes to UV cutoff.
I used a calibrated Ocean optics spectrometer with a cosine corrector for my measurements. There are no details from the other reported measurements.
The STC595 in that graph refers to a STC drop in filter (meant to be used with a full spectrum camera).
Then what is the explanation? Is in the increase filtering between 380-400nm? Is there cumulative effect, where the filter and stack together are additive in nature? Could it be just my cameras? Is there some fluorescence in these lenses?
Is your test average this across the whole frame or sampling a portion? This curve is exactly the same in the center and at the edges and corners, with no deviation, including with a lens mounted where ray angle may come into play more?
I'll revise my post and soften my comments around the "why". I will say "no one knows" from now on, that seems to be the safest bet.
My last question would be, based on your test, do you feel there should be as noticeable change between bare lens and Kenko filtered lens photos? In other words, is your test confirmed in the test shots I have posted and vice versa?
realVivek wrote:
Tim, I do not agree with the speculation that there is some edge/corner leakage of the Sony filter stack. I already posted that in reply to inks&paper. The Sony stacks are virtually indistinguishable from that of a Kenko Zeta L41 filter when it comes to UV cutoff.
I used a calibrated Ocean optics spectrometer with a cosine corrector for my measurements. There are no details from the other reported measurements.
The STC595 in that graph refers to a STC drop in filter (meant to be used with a full spectrum camera).
