[OM] Re: Tamron 350/5.6 cat

[Jeff Keller]

I think the Sigma cat lens had a large lens cap which had a single circular 
hole in the center which had another removable lens cap.  That combination 
offered the one additional aperture setting when the big lens cap was 
installed but the smaller center one was removed. I just vaguely remember a 
description of it. I never saw it.

I think some of the soft focus lenses use(ed) numerous off axis holes but 
evenly distributed around the axis to give variable softness. As the lens is 
stopped down different holes are covered up. I guess the multiple holes 
would give a shallower DOF than the aperture setting would imply and also 
add more diffraction.

I located two for sale listings for the Ohnar 300/5.6. Both were in the UK. 
The cheapest was 20 pounds. Apparently one sold on yabe not too long ago. It 
showed up in google but yabe said it was an invalid no.

-jeff

----Original Message Follows----
From: Moose <olymoose@xxxxxxxxx>


Jeff Keller wrote:
 > There was a very fast fairly long Sigma cat that used the lens cap to 
stop
 > down the aperture. I've only seen one offered for sale. It was at Adorama
 > several years ago and had a price tag of very roughly $1000.
I seem to recall that some cat lens with a cap to change the aperture
used a series of circles evenly distributed around the glass portion of
the front element. Or was that soem other thing?

Moose



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