Protective filters and image quality

Started Sep 2, 2013 | Discussions thread
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bkpix Contributing Member • Posts: 734
Protective filters and image quality

Hi all,

I have for many years used protective UV filters on most of my lenses on the assumption that a little bit of degradation in image quality was worth the protection from smudges and scratches.

This afternoon I decided to find out just how much that "little bit" was. In brief, I was very surprised at the price you pay for putting a filter in front of the lens.

I tested two setups: my K5IIs with a 16-50 DA* at 16mm, and my Canon 7D with a 100-400L lens at 400mm, in a simple series of outdoor landscape shots off a tripod. Nothing fancy.

The image quality difference on the long lens on the Canon was stunning. Taking the filter off was like having an entirely new and better lens at my disposal. The difference was in contrast, not in sharpness or resolution, but it was huge. All this time I've been essentially taking photos through a dirty windshield, it seems.

There was much less impact on the wide lens on the Pentax, but it was certainly there. At first you wouldn't notice, but if you look at tree branches out on the horizon, there is a significant difference in fine detail, contrast and color when using a filter.

(Anyone out there own a Pentax DA* 300 or 60-250 want to try this out and report back?)

It's clearly time for me to rethink all this. I may leave the filter on the 16-50, as the front element is very exposed even with the hood on, and remove it for individual photos. But the filter on the 100-400 will be coming off forever (and the lens hood will be taped on, for extra insurance).

Oddly, I have never used filters on my two Limited lenses, the 21/3.2 and the 70/2.4. Both have recessed elements with plenty of protection from their hoods. Maybe that's why they've always seemed extra sharp.

Moral of this tale: Test everything, especially all your assumptions.


 bkpix's gear list:bkpix's gear list
Pentax K-5 Pentax K-5 IIs Canon EOS 6D Canon EOS 7D Mark II Pentax KP +13 more
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