I have a 50mm prime lens, chosen due to great reviews. I bought mine second-hand from a very reputable store. Unfortunately, the 'sweet spot' (middle part of the image) is slightly fogged in my images. I think this comes from marks in the coating on the back glass of the lens. Cleaning with lens cleaning fluid has not altered the marks. Is there something else I can do?
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2\$\begingroup\$ Could you be more specific regarding the marks on the lens? Posting a picture would be best. \$\endgroup\$– EmilCommented Aug 6, 2017 at 9:53
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1\$\begingroup\$ The marks are marks in the coating - some tiny and short (but they don't seem to be scratches) and the others resemble wipe marks (which is why I expected cleaning with lens cleaning fluid would work). I've added a picture taken with my laptop camera, but it's not very clear so I will try to upload a better picture later. Thanks! \$\endgroup\$– user59085Commented Aug 6, 2017 at 11:43
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1\$\begingroup\$ My advice would be to contact the reputable store and explain the problem because handling problems with used lenses is part of what makes a camera shop reputable. \$\endgroup\$– user50888Commented Aug 6, 2017 at 13:52
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\$\begingroup\$ Usually if a stain on the lens doesn't come off after using light soap and cloth to clean it it's probably a permanent damage. Could be from previous fungus or improper cleaning. Hard to tell exactly from the image. \$\endgroup\$– EmilCommented Aug 6, 2017 at 14:55
1 Answer
Yep, I'd recommend returning it since if mild cleaning doesn't affect it, the coatings are likely scratched, and more vigorous rubbing will only make things worse (though I'd recommend trying a lens pen if you have one handy). In my experience, defects on the rear element are much more problematic than those on the front element, but that said, if it was a really good deal and you're set on keeping it, test it under some challenging lighting conditions and see how it fares in terms of sharpness and flare, maybe it'll be fine. High contrast areas are the first place I'd look for problems.