The Filters We Need With Digital...

Started Oct 5, 2008 | Discussions thread
OP Joseph S Wisniewski Forum Pro • Posts: 34,136
Now that is just weird...

Iliah Borg wrote:

I have just bought a
Tamron SP 300mm f2.8 LD IF and while searching for sites with more
info about it I came across a lens test with a remarkable
finding...As you probably know, Tamron used to offer an optional
112mm "normal" filter for the front of the lens. I dont know what a
"normal" filter is but apparently the tester has found his Tamron
300/2.8 to be considerably sharper with this filter on the lens than
without it!!!

I had a similar experience with Canon 1D MkII and long lenses. A UV
filter improved AF performance of the camera.

Iliah, that is just plain weird. Not that I'm doubting you, I've seen enough weird stuff in this world to know that "weird happens".

But I can't imagine how, unless the AF system was unusually sensitive to UV, so that whatever was making it through the lens was enough to drift the AF system off a bit (since the lens isn't corrected for near UV, or even for violet). Even then, a long lens should block pretty much as much UV as a filter...

Were you using a stronger UV filter, a UV(1) or something that cuts off near (or even above) 400nm, like those 415nm UV filters I use for blacklight sessions...

-- hide signature --

Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

 Joseph S Wisniewski's gear list:Joseph S Wisniewski's gear list
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