Originally Posted by mark_pw
I think I'm new to this stuff.
This lens has the aperture blades exposed.
I wonder if any dust or particles could be trapped between the blades and scratch or stuck them. They look fragile.
I was surprised when I bought the first AF version of Nikon's 180mm f2.8 ED lens (the one with the shiny plastic barrel and skinny MF ring that people dislike for mainly aesthetic reasons). And lo and behold - it has no rear element to close the innards and protect the aperture blades. Not even an optically flat element that has no optical purpose.
Apparently the 300mm f/4 AF-S has the same "feature" (Provided by Nikon at no extra cost :^) )
I have seen plenty of old long lenses with nothing at the rear of the focusing mount (all the elements are at the front) but never with the aperture exposed to this degree - usually the iris has at least one element behind it and at least a couple in front.
So I was a bit gobsmacked when I got mine but I have had that lens for 10 years and so far...so good.