“The simple answer is "yes", adding any filter to your lens will degrade the image to some extent.”
“Yes, there is plenty of visual evidence if you just take the time to look for it (or do your own tests).”
The correct answer to the first statement is, yeah it will, at least in a laboratory. The correct answer to the second statement is not nearly so cut and dry. For one point, it depends on how you intend to show your work.
The agreed upon “degrade” is closely tied to that fact.
Take time to “do your own tests”? OK here is a shot I was about to delete but decided it was a good example to show exactly what is a real world situation. Nothing going for it and a lot not optimal, to say the least.
This photo could not have had any worse conditions to shoot with. Unless it was raining, I guess.
This was taken with my 120-300mm f2.8 zoom lens. Yes this photo has a filter on the lens. And in addition it had a 1.4x tele converter! In addition I was walking and it is hand held. Look for yourselves. Would this do for Facebook? Would it print?
Can you pixel peep it? Is any body going to say if only it didn't have a filter on it. Here is a 100% crop and better yet a 200% crop. That is about as tough as it gets for scrutiny.
I am not wanting any critical acclaim, this is just an example. Make up your own mind.
