28mm is 28mm > > > Bob >
I think this is an oversimplification. Certainly the design of the front of the lens housing (not the optics) has an impact upon whether or not a filter of a particular thickness will cause vignetting. So while 28mm is 28mm, not every 28mm lens will behave the same when it comes to filters.
Does this make sense to anyone else?
Yes, I was thinking the same thing. Some lenses are built further out in front of the front element, perhaps to the design limit of vignetting, causing anything additional to show. I'm not claiming this is the case with the lenses under discussion, and I've had no vignetting problems with my 28-135. But I don't own a 28-105. But I think it's a valid question. F-stop makes a difference as well. I have lenses that vignette wide open with any filter but not when they're stopped down a bit.
Ken
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