I don't think I made myself very clear. I was trying to imply that a
mirror lens made specifically for a 4/3 body might allow a smaller hole
in the primary mirror. That, in turn, would allow a primary mirror of
smaller overall diameter and allow a shorter focal length than the
typical 500/8.
The Tammie 500 was designed for 35mm use and has a perforation in the
primary suitable for passing a 35mm image circle. Had it been designed
for 4/3 it would presumably be smaller as would the secondary. A large
secondary mirror is the cause of contrast robbing diffraction. Or maybe
it was me who has misunderstood you...
Chuck Norcutt
Andrew Fildes wrote:
> We need someone to test that. Using a Tamron Adaptall or a T mount.
> I've got the Tammie 500 lens but no 4/3 body. Er, Wayne....?
> Andrew Fildes
> afildes@xxxxxxxxxxxxx
>
>
>
> On 03/03/2007, at 10:44 AM, Chuck Norcutt wrote:
>
>> I've never thought much about the problem but in thinking about it
>> now I
>> assume that there are some physical constraints in passing the image
>> through a hole in the primary mirror with the hole being large
>> enough to
>> deliver an image across a full size 35mm frame. (no one is yet making
>> mirror lenses for 4/3 mounts). If the mirror was small then there
>> wouldn't be much left after making a large hole in it. A shorter
>> focal
>> length lens could have a larger mirror if it was a very fast optic but
>> very fast lenses have lots of other downsides not the least of
>> which is
>> cost and weight.
>
>
>
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