We all have been in that situation at the camera store where the salesman asked us if we want to add a protective filter to protect the front element of the expensive lens that we have just bought.
And the argument of the salesperson sounds plausible at first. The front element is exposed the most to the elements and most at risk to be damaged. But here are a few points from my experience that should have you think twice about buying and adding one to your lens:
Do you really want to put an inferior piece of glass in front of you top grade optical lens glass? The extra piece of glass can cause unwanted reflections, flare, loss of contrast and slow down AF. You may be able to catch those unwanted reflections as “ghost lights” if you take a picture of your lit Christmas tree. And those are hard to cure in post processing.
Many lenses will have the front element slightly recessed behind the filter thread. If the lens ever touches a flat surface such as a wall, it’ll most likely damage the filter thread part first. And (wide-angle) lenses where the front element sticks out you can’t add a filter in front anyway.
I have been photographing for more than 30 years. And I have never damaged a front element so far. What has been most effective for me is using the lens hood in situations where the lens could take a beating. And you have the added benefit of increasing the image quality and contrast of the lens by cutting out stray light from hitting the front element, too. Win-win :)
Those are the reasons why I don’t use any “protective” or “skylight” filters for any of my digital cameras. I only use filters for special purpose such as ND or polarizing that give me a real benefit of an effect that I can’t get in post processing.
Wishing all of you all a Merry Christmas without unwanted reflections from “protective filters” and Happy Holliday’s!