Hi,
I think you will be disapointed with a camera mirror lens. I have once tried a Russian Rubinar mirror lens, it was sharp but the contrast was low. I have had some others too, always they have been of low contrast. Most people I believe feel this too when trying to do astrophotographing with camera mirror lenses.
I have collected some links with review that maybe can be interesting to read:
http://www.astrofriend.eu/links/link...my-review.html
As a travel equipment it had been very good if just the quailty had been better.
Maybe there are others that's more optimized to astrophotographing. If you find one, let us know!
Here is a list of what equipment I have/had:
http://www.astrofriend.eu/astronomy/...equipment.html
Lars