[OM] Re: Tamron 350/5.6 cat

[Moose]

Chuck Norcutt wrote:
> The easiest way would be to apply an aperture mask to the front element. 
>   Aperture ranges would be pretty limited though if the aperture had to 
> be round.  No reason why it can't be oval or kidney bean shaped though.
>
>   
Chuck Norcutt wrote:
>> It's not impossible to put a diaphragm in there, just mechanically 
>> difficult.
>>     
That is just what they did 
<http://www.excite.co.jp/world/english/web/?wb_url=http%3A%2F%2Fhomepage3.nifty.com%2F3rdpartylens%2Dom%2Fohnar.htm&wb_lp=JAEN&wb_dis=2>.

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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