In article <48t6n5$19sh@saba.info.ucla.edu>, myid@ucla.edu says...
>I am considering buying a 500mm/f8.0 mirror lens. It will be
>used on my Minolta X-700. The original Minolta would be too
>expensive for me, so I am thinking of some off brand stuff.
>The ones in the market are:
> 1. Vivitar, about $110
> 2. Tokina, about $230
> 3. Tamron, about $350
> 4. Sigma(?)
> 5. Crambon or whatever really off brand thing
>Could anybody there tell me their experience with these
>lenses? Especially do you think the Tokina etc. really worth
>twice or three times the money of the low end Vivitar?

Minolta makes some excellent mirrors - I would be inclined to look for
a used MF Minolta 500mm (should be no more than some of the prices
quoted above, and my guess is that it would be better than any of the ones you mentioned [I have tried some of them]). A poor mirror is a
VERY poor lens! Get a good one, if you can.
Hope this helps.