Protective Filters Part II: Is it worth covering the face of your lens?
When I wrote about the thorny dilemma of whether or not to fit your lens with a UV filrer (primarily as protection for the front element) I had no official angle from any lens manufacturer. As it turns out, however, I was unintentionally stirring a hornets' nest.
I quoted Lens Rentals' experience from a damage and repair aspect and Roger Cicala’s investigations into the possibility of image degradation, including perceived disadvantages of additional reflection from that extra bit of glass, however refined. Some of the most expensive filters, including a very costly 77m Leica glass, suffered from the lowest degrees of reflection. So, again, you get what you pay for and it is clearly risky to attach an inferior filter to a £1,000 or £5,000 lens.
Thanks to regular reader Frank Neunemann I came across some interesting side information, including a presumably unguarded comment from a "Leica person at the factory":
"If we had intended our lenses to have flat pieces of glass in front," he said sternly, "we would have designed them that way."
That comment will gladden the heart of colleagues such as William Fagan who made precisely this point in a comment on the original article. And there will be many readers to agree with him.
It is definitely a trade off between the very slight possibility of image degradation against the added safety and convenience of the pesky bit of glass. If you hate lens caps, then the trade-off might just be worth it. At the moment I’m still a filterer, but who knows what I could decide in the future?
See the first part of the discussion on using filters — and don't forget to check the comments section of that article.