Mirror lenses of less than 500mm focal length are quite rare as are
apertures larger than f/8. I think someone made a 350mm mirror lens
long ago but I can't remember who it was.
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.
I think you'll find that the industry has settled on 500mm f/8 as the
smallest practical size they'll produce.
Chuck Norcutt
Allen Coltrin wrote:
> Hello whoever has a lens to sell. So, if you are interested in selling to me
> first, I need to replace the lens that went down in flames on ebaay. I am
> looking for a lens of 350 or 400mm lens with a 2x TC. I just want to keep
> the weight down without loosing too much in distance. I woulld prefer a
> mirror lens if possible. Zuiko, Tamron, Tokina.
>
> Thanks a lot,
> Allen
>
> _________________________________________________________________
> Rates near 39yr lows! $430K Loan for $1,399/mo - Paying Too Much? Calculate
> new payment
> http://www.lowermybills.com/lre/index.jsp?sourceid=lmb-9632-18226&moid=7581
>
>
> ==============================================
> List usage info: http://www.zuikoholic.com
> List nannies: olympusadmin@xxxxxxxxxx
> ==============================================
>
>
>
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|