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4 Days Ago - 1 Like   #1
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Use of UV filters to reduce purple fringing?

In a recent thread, one of our members - @MossyRocks - educated me as to the use of certain UV filters with certain lenses to improve digital astro photography, and kindly provided a link to another thread by @Lew Dite; with off-site links discussing this application:
Deneb Region 100mm Astrotracer - Astrophotography - PentaxForums.com
Having read the linked content, it seemed to me that this use of UV filters mightn't just be limited to astro photography, but potentially all instances where "purple fringing" is present. So I did a little Googling and, sure enough, I found a few references to the use of UV filters to reduce fringing.

So, I wanted to ask, has anyone successfully used a UV filter to reduce purple fringing on an affected lens / camera combo in general use (rather than astro specific)? I can test this myself and fully intend to - possibly using the D FA 100mm f/2.8 Macro WR where purple fringing can be easily induced at maximum aperture. But I can only use those UV filters I own, which are mostly Hoya HMC UV(c) - and, as I understand it, the spectral filtering of UV filters varies considerably. Hence, my tests may not be conclusive.

I imagine some folks will say that any benefit can be duplicated using CA / fringe removal in post-processing, but of course this isn't the same, since it's basically desaturating specific colour ranges in the affected areas.

And, of course, I'm fully aware of the potentially detrimental effects of using UV filters. This thread is just addressing whether-or-not there is any benefit in purple fringing reduction

Any information and thoughts would be much appreciated


Last edited by BigMackCam; 4 Days Ago at 03:47 PM.
4 Days Ago   #2
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I tried this some time ago on a SMC-M 80-200/4.5 1st version, and I'm afraid the potentially detrimental effects are one and the same with PF reduction.
That lens is prone to PF on high-contrast edges, and it goes hand in hand with its high resolving power.
Now, the fact is that different wavelengths focus at different distances, and, before ED glass, one could focus 2 primary colors out of 3, but never all three at the same time, hence the fringing.
UV filters just muddle the image, kill resolving power and PF with it.
So, yes, one can use an UV filter to reduce PF, but the price to pay is too much IMHO, and has nothing to do with cutting certain wavelengths, which is what one might be tempted to infer at first glance.
4 Days Ago - 1 Like   #3
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I have used the Hoya HMC UV[0] filter with my Sigma 400mm f/5.6 APO Tele Macro and have noticed no reduction in purple fringing.
4 Days Ago - 1 Like   #4
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UV 2a on a Tokina 400 f5.6 kinda worked, small color shift. IIRC there's a warming filter I tried that worked OK. I'll have to dig around and find it to get the number. PF tool and newer glass works better.

4 Days Ago   #5
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I have a B+W 010 UV Haze 1x MRC filter mounted on my Sigma DC 17-70mm 1:2.8-4.5 zoom. I see some occasional slight purple fringing in high contrast areas. I haven't tried an A-B comparison between using and not using the filter, though.
4 Days Ago - 1 Like   #6
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The only reliable article I've read about this required a very strong filter that isn't easy to find. It also specifically pertained to Olympus and Panasonic m43 use - I can't recall whose lenses on which have issues due to differences in uv filtering in the bodies vs lenses.
4 Days Ago   #7
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Since most digital cameras have a UV/IR blocking filter in front of the sensor, it doesn't make too much sense that an additional UV filter over the lens would have any effect. Perhaps on a film camera where the film has noted UV sensitivity, but I don't think it would be worth the effort with a digital camera (there might be some exceptions since some lower cost digital cameras forego the blocking filter) .

Last edited by Bob 256; 4 Days Ago at 05:13 PM.
4 Days Ago   #8
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It is probably much better to invest in a new lens, a lens that is corrected from aberration of colour (chroma/fringing). The idea that a UV filter can be put on and that is the end of it will do nothing to fix the inherent failing of the lens optical properties.

4 Days Ago   #9
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QuoteOriginally posted by BigMackCam Quote
In a recent thread, one of our members - @MossyRocks - educated me
I would hardly say educated, only pointed out what another member had done the work on.
3 Days Ago   #10
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QuoteOriginally posted by LensBeginner Quote
the fact is that different wavelengths focus at different distances, and, before ED glass, one could focus 2 primary colors out of 3, but never all three at the same time, hence the fringing
^This^ basically. Achromatic lenses are cheaper to make and require lower tolerances than fully apochromatic lenses do. This is the primary reason I use apochromamtic lenses for macro work* since OOF rendering is so important in macro work (and OOF areas are more frequently encountered) reducing colour fringing is imperative.



Pentax K5IIs - Sigma 180mm f/3.5 APO Macro @ f/5.6 ISO80 1/180th - Godox AD360@ snoot with grid at 1/8th power. Note the complete absence of colour fringing





* The Pentax FA200mm f/4 ED is not explicitly described as an apochromat. Though from the resulting image quality tests I have subjected it to I have no reservations in saying it qualifies as an apochromat.
3 Days Ago - 1 Like   #11
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QuoteOriginally posted by MossyRocks Quote
I would hardly say educated, only pointed out what another member had done the work on.
Call it what you will, you brought something to my attention that I wasn't previously aware of - and I thank you for it
3 Days Ago - 1 Like   #12
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The better and more expensive UV filters are those that can filter out UV without reducing visible light transmission significantly. Hence, the best ones won't filter out purple as much as the cheap ones (which are basically the equivalent of weak yellow gels). And, since cheap ones will affect image quality and light transmission generally at the blue end of the spectrum, I don't see a UV filter being much use for reducing purple fringing. And, since lateral chromatic aberration is the result of the distribution of light at different wavelengths that's coming into the lens rather than an artifact of the lens itself, reducing the magenta that's coming in will affect the photograph generally - i.e., you can't reduce purple fringing with a filter without reducing the blue end of the spectrum throughout the picture. Maybe it won't be perceptible, I don't know.

All theory aside, I use high-quality UV filters on all my lenses, 98% transmission or better. I don't know if that helps with the PF, never actually experimented with it. Couldn't hurt, though.
3 Days Ago - 2 Likes   #13
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QuoteOriginally posted by dlh Quote
The better and more expensive UV filters are those that can filter out UV without reducing visible light transmission significantly. Hence, the best ones won't filter out purple as much as the cheap ones (which are basically the equivalent of weak yellow gels). And, since cheap ones will affect image quality and light transmission generally at the blue end of the spectrum, I don't see a UV filter being much use for reducing purple fringing. And, since lateral chromatic aberration is the result of the distribution of light at different wavelengths that's coming into the lens rather than an artifact of the lens itself, reducing the magenta that's coming in will affect the photograph generally - i.e., you can't reduce purple fringing with a filter without reducing the blue end of the spectrum throughout the picture. Maybe it won't be perceptible, I don't know.

All theory aside, I use high-quality UV filters on all my lenses, 98% transmission or better. I don't know if that helps with the PF, never actually experimented with it. Couldn't hurt, though.
I don't think the visible spectrum is necessarily to blame. Read this: Purple Fringing with Panasonic MFT Lenses on Olympus MFT Bodies This addresses the real world interactions of Panasonic and Olympus uv filtering differences. It may not fully apply here but I think the basic idea is relatively useful in this discussion.
2 Days Ago   #14
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I experimented a bit on the Pentax Q with ir-uv cut filters. I wondered if invisible uv and infrared was being read by the sensor as red and blue. The result was by no means conclusive but I felt the gain outweighed the negative IQ of a filter.
Fringe killing the Q - PentaxForums.com
2 Days Ago   #15
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QuoteOriginally posted by GUB Quote
I wondered if invisible uv and infrared was being read by the sensor as red and blue.
IR would not be seen as red and would just show up as luminance contamination. A good way to test for this is to photograph a highly reflective surface in IR - that isn't reflective at all in visible light against a completely non-reflective surface in visible or IR light. The same testing methodology would work for testing UV, however finding a material outside the laboratory that is easy to come by that reflects UV without reflecting any visible light itself would be difficult.
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