John Mitchell Posted April 22, 2016 Share Posted April 22, 2016 Just wondering, has anyone found that protective, multi-coated UV filters can sometimes cause (or contribute to) chromatic aberration with some lenses? Link to comment Share on other sites More sharing options...
hdh Posted April 22, 2016 Share Posted April 22, 2016 Very interesting question. never thought about this so far and am very curious to the answer. Also an interesting topic to test, the next time I am out taking photos. Link to comment Share on other sites More sharing options...
spacecadet Posted April 22, 2016 Share Posted April 22, 2016 There's no optical reason for it to happen. Link to comment Share on other sites More sharing options...
Niels Quist Posted April 22, 2016 Share Posted April 22, 2016 Protective filters are a religion, for once I am for. I don't think they contribute to CA. Link to comment Share on other sites More sharing options...
DDoug Posted April 22, 2016 Share Posted April 22, 2016 It seems to me that the raw conversion software which corrects CA based on the amount it detects in the image would not be thrown off by any additional bit added by a filter. If a good brand of filter such as Heliopan or B+W is used, the already negligible (or perhaps nonexistent) risk of added CA would be even less. Link to comment Share on other sites More sharing options...
giphotostock Posted April 22, 2016 Share Posted April 22, 2016 A flat plate of glass in front of a lens in an imaging system should introduce zero chromatic aberration. It will introduce non-zero spherical aberration but that will be noticeable only for very thick plates. GI Link to comment Share on other sites More sharing options...
CarlMillerPhotos Posted April 22, 2016 Share Posted April 22, 2016 If it's not there for a reason, like polarization or color correction, then why put another piece of (possibly very cheap) glass in front of your expensive lens? Link to comment Share on other sites More sharing options...
hdh Posted April 22, 2016 Share Posted April 22, 2016 If it's not there for a reason, like polarization or color correction, then why put another piece of (possibly very cheap) glass in front of your expensive lens? Depends on the environment you are in. Say desert (or beach) plus lots of wind can easily ruin your lens outer glass. It is much cheaper if it is the UV filter which is ruined. Also when carrying two bodies and you bump one glass into something. Its for pure protection. Also it is philosophical, generally I agree, why put something on it if its not there in the first place. So not all my lenses have UV filters - only the ones that I need ruggedized for one reason or another. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 22, 2016 Author Share Posted April 22, 2016 Thanks for the responses. It sounds as if no one has found CA in their images that can be traced to a UV filter. I use pretty good ones, B+W and Hoya HMC. Reason I'm asking is that I'm sometimes seeing what looks like very fine lateral CA (I think) in the centre area -- not the edges -- of images when I use a particular zoom lens. It's almost impossible to correct using CA sliders, so it might just be due to reflection. I put on a new Hoya UV filter on this lens not long ago and wondered if it might be the culprit. Shall have to do some tests with and w/o the UV filter. Link to comment Share on other sites More sharing options...
spacecadet Posted April 22, 2016 Share Posted April 22, 2016 Beware of CA that is actually unfixable colour flare. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 22, 2016 Author Share Posted April 22, 2016 Beware of CA that is actually unfixable colour flare. Right, this might be what I'm dealing with here. I've never seen any colour flare this fine, though. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 23, 2016 Author Share Posted April 23, 2016 P.S. I don't see "colour flare" listed anywhere in Alamy's reasons for QC failure, so I imagine that a certain amount of un-fixable flare is acceptable. Correct? Link to comment Share on other sites More sharing options...
TABan Posted April 26, 2016 Share Posted April 26, 2016 By color flare, I think SC means purple fringing, which isn't CA. I commonly see it in tree branches against a bright sky with lenses that otherwise have low CA. Lowering exposure a bit helps. Link to comment Share on other sites More sharing options...
spacecadet Posted April 26, 2016 Share Posted April 26, 2016 It can be various colours- orange with a sunset, for example. I've noticed it but not worried about it. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 26, 2016 Author Share Posted April 26, 2016 I only get purple fringing with very wide lenses, and it's usually easy to correct, or crop out if necessary. Link to comment Share on other sites More sharing options...
spacecadet Posted April 26, 2016 Share Posted April 26, 2016 Colour flare has been discussed on the forum a time or two. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 26, 2016 Author Share Posted April 26, 2016 Colour flare has been discussed on the forum a time or two. Yes it has. Not 100% sure that what I'm seeing is colour flare, though. Guess I'll have to add it to my list of unsolved optical mysteries. Link to comment Share on other sites More sharing options...
spacecadet Posted April 26, 2016 Share Posted April 26, 2016 Do share if you care for a bit of endless pontificating. Link to comment Share on other sites More sharing options...
John Mitchell Posted April 26, 2016 Author Share Posted April 26, 2016 Do share if you care for a bit of endless pontificating. Thanks, but it's already in my "cold case" file. Link to comment Share on other sites More sharing options...
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