Effects of Filters on Image Sharpness

There are many discussions on the internet about whether a filter in front of a lens reduces the sharpness.

It is obvious that by using a filter in backlight situations, by using a cheap low-quality filter or by stacking two or more filters you will reduce the image quality.

But the question of whether a single high-quality filter will reduce the image sharpness even in situations with diffused light is not yet clearly answered. Therefore I did some tests by myself.

The tests were done with my Nikon D800E on a stable Gitzo tripod with a self-timer and mirror-lock-up. The focus was done in live-view at max zoom on the center of the frame.

As a test object I used a flat wall at a medium distance of 5-10m:

Test Wall

First I tested the Zeiss 2.8/21mm ZF.2 wide-angle lens with different filters.

Zeiss 21mm, no filter, f/8, 100% crop of the center:

Zeiss 21mm no filter

Zeiss 21mm, B+W 007 Neutral MRC F-Pro protection filter, f/8, 100% crop of the center:

Zeiss 21mm protection filter

Zeiss 21mm, B+W KSM C-POL MRC SLIM polfilter, f/8, 100% crop of the center:

Zeiss 21mm polfilter

Then I tested the Zeiss Otus 1.4/55mm standard lens with and without a filter.

Zeiss 55mm, no filter, f/5.6, 100% crop of the center:

Zeiss 55mm no filter

Zeiss 55mm, B+W 007 Clear MRC nano XS-Pro protection filter, f/5.6, 100% crop of the center:

Zeiss 55mm protection filter

Short conclusion: I don’t see any significant differences between the images shot with and without a filter. If I don’t see it in a 100% crop it shouldn’t matter on large prints.

Of course, if I shoot against the sun I will still remove my filters but in all other situations, I will not hesitate to use a protection filter (or a polfilter, if the situation requires this).

By the way, the main purpose of a protection filter is not to protect the lens from an impact but from dust, mud, fingerprints, cleaning marks, and especially salt spray near the sea.

One thought

  1. Thank you. Very informative. I used two filters on a bright day when shooting a highly polished silver metal building. I loved the effect. I never noticed a loss in clarity

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