Image degradation with UV filters

Started Mar 23, 2012 | Discussions
DAVID MANZE
Senior MemberPosts: 1,405Gear list
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Image degradation with UV filters
Mar 23, 2012

Hi guys,

After receiving my Pentax 50mm F1.4 lens and setting up the AFFA, from F2.0 the sharpness was very good, but on rising to F5.6 there was a deterioration in the bottom right of the photo, which improved on further stopping down.

Scratching my head I found this strange, what was causing that? sharper @ F2 than at F5.6! Hang on, I'll try it again with without the UV filter. The same series of photos at all apertures,this time all is good, so it was the UV filter causing the problem! Admittedly, it wasn't an expensive one but of a reputable make.

I like to protect my lenses with UV filters and they all have one, so I decided to check out another acquisition, my Carl Zeiss jena 75-300mm F4.5/5.6, I had just received the UV Hoya multicoated (highly rated at LensTip.com) The AFFA had been set up to +10 without a filter and all looked good,but when taking photos of views over the sea with a filter, I noticed that there were "interference" patterns (newton's rings) which were visible only on the sea,also the +10 AFFA didn't seem sufficient,taking off the filter cured both problems.

So maybe it's worth a check next time you are looking at photos that for some reason don't seem to have sharpness that you expected, to check out the effects of the UV filter.

Conclusions with these two lenses, 1. there was a deterioration in the quality of resolution(Pentax), an alteration in the AF and the newton's rings(CZJ),even with top quality Hoya SMC UV filters!

I haven't seriously checked my other lenses but I'm keeping my eye open.Now with both lenses I don't use a UV filter.

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 DAVID MANZE's gear list:DAVID MANZE's gear list
Sigma 50-500mm F4.5-6.3 DG OS HSM Pentax K20D Pentax K-5 Pentax K-01 Pentax K-3 +16 more
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jamesm007
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Re: Image degradation with UV filters
In reply to DAVID MANZE, Mar 23, 2012

Interesting. I have no answer or even an idea as to why.

I do use Hoya PRO 1 Digital UV and Protect filters and one Kenko Digital filter. I also have Hoya CPL (regular) filters for all my lens.

I have used a filter and it did harm IQ I was just starting and did not know how bad a bad filter could be. The filter was not even coated, but I did not know it should be! I did have a bad CPL filter that would distort the pic under certain heat/humidity conditions. I have since purged my system of all bad filters.

I do check clean and test occasionally my filters. I even test for flair. So far using Hoya Digital filters I can not prove they help or harm any pic in any situation I have tested. My Sigma 10-20mm is one lens I keep a real close eye on the filter because of flare issues. However anytime there is flair in the picture removing the filter has not helped at all.

I agree people should check now and then that the filter is not doing something they don't want.

 jamesm007's gear list:jamesm007's gear list
Pentax K20D Pentax K-5 Sigma 10-20mm F4-5.6 EX DC HSM Pentax smc DA 55-300mm F4.0-5.8 ED Sigma 17-70mm F2.8-4 DC Macro OS HSM +9 more
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ccd
ccd
Regular MemberPosts: 370
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Re: Image degradation with UV filters
In reply to DAVID MANZE, Mar 23, 2012

I noticed this with my new K-r immediately.....with both new kit lenses. The same UV filter I was using with my *istDL created considerable image degradation on the K-r. Which is interesting since the older DL with the older 18-55 does not suffer any loss with the same filter.

I now use one of those ultra thin UV filters and they work perfectly for the K-r and any lens so far.

I have not tried putting the old filter on the new lenses with the old DL.....but now I'm curious.

Confused?

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