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11-10-2011, 05:12 PM   #1
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Pentax 35-70mm 2.8 AF saw blade aperture?

I recently came into this lens and it's been great fun to play with. It can get a little too dreamy wide open, but it's tack sharp stopped down and seems distortion free on the shots I've taken so far.

Its aperture geometry, however, has left me puzzled. From wide open to f8 the blades form more a saw blade shape than a simple octagon, as if they're misaligned and that misalignment can only be hidden from f8 and beyond. Of the lenses at my disposal, only my FD mount Kalimar 28mm 2.8 exhibits something similar, and only at f4.

Excuse the question if it's indicative of my inexperience, but is this normal for this lens?

11-10-2011, 06:03 PM   #2
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Don't worry, our copy looks exactly the same!
11-11-2011, 05:55 AM   #3
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Good to know, thanks!
11-11-2011, 06:05 AM   #4
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There are several other pentax lenses that have *teeth* too. Normally, near wide open. They all look the same as yours...
Until I take a closer look of the K28/3.5shift at f8 ;-)


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