Filter Distortion/Flare

bwcolor

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A recently renovated thread debated the use of filters, especially for protection. I have always used filters as protection, but suspecting that optical quality was of importance, have only B+W MRC on the front of my lenses.

I don't question that such use would demonstrate some level of degradation on an optical bench. I'm guessing that with and without photos might reveal increased flare with a quality filter, but do you have evidence of other optical drawbacks when using a quality filter? To put the question another way, does this degradation show-up in your images?
 
Are you happy with your images?

I suspect a few scratches on the surface of the lens would be far worse than a high-quality filter. If someone gives you a hard time over using a filter for protection, be sure to check the front surface of their lens.
 
I don't question that such use would demonstrate some level of degradation on an optical bench. I'm guessing that with and without photos might reveal increased flare with a quality filter, but do you have evidence of other optical drawbacks when using a quality filter? To put the question another way, does this degradation show-up in your images?

Lots of comparisons on the bench and in the field here.
 
I use mostly B+W or Hoya multi coated filters on all my lenses, simply because I stuff gets dirty quickly, as I live close to the ocean. For B+W using a permanent yellow filter is good, too, improving skin and sky tones.

However: if you like OM Zuikos, you know and likely respect Gary Reese and his tests. He added an interesting note about negative filter impact in one of his tests (50/1.4 MC):

Reese/Norton said:
Notes: Differences are significant at the 1/3 grade level in this paired comparison evaluation. Contrast was slightly lower with the filter, but lower resolution was the most important factor in image deterioriation. Please note that this particular filter is not indicative of Vivitar or Vivitar VMC filters, in general. It just tested as a poor sample. Other filter makers, even the most highly regarded, have been found to have poor samples in selections taken from used and new stocks of filters.

The use of the term "poor" means star test images, viewed on a vertical auto collimeter, which show images that are: multiple and overlapping, fuzzy, off center, and images which rotate when the lens is rotated. More often than not, only one of these faults are found in an examined filter. These filters (including the test filter) often look perfectly good when examined without the aid of instrumentation!
 
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