I actually got a Contax-Yashica mount Tokina 500mm f8 mirror lens a very nice gentleman in CS, and then mod the mount to fit Pentax K bodies. I also managed to buy a Russian M42 mount MTO 1000mm f10 mirror lens from another very nice gentleman in CS.
Hard to find Pentax K-mount mirror lens here, I think. That's why the Sigma 600mm f8 K-mount mirror lens was a hot item in a recent BnS bidding. I am sure the successful bidder will treasure the rare find.
Yup...why I appreciated the mirror lens more is because of my love for astronomy also... Thought of using it to take the moon as the lens is too heavy for continuous use. I can't figure if this is a Mak or SCT though...looks more like a Mak disguised as an SCT! Its strange people here call them mirror lenses because I am so used to calling them Maks..or scopes..heh heh
But I had to admit the images were a little soft but this is one moment you really appreciate the K100D anti-shake function.
I was able to get most of the shots without blur.
One quick way to tell if it is a MCT or SCT is to look at the front glass plate upon where the secondary mirror is fixed (remember to take off any front filter first or you will be misled by the filter). A curved-in spherical front glass plate is indicative of a MCT, while a flat front glass plate suggests an SCT.
My Tokina 500/8 mirror lens seems to be an SCT, while my Russian MTO 1000/10 mirror lens is definitely a MCT.
The 'softness' of image is probably due to less contrast (the central obstruction has to do with it). If you shoot with highlights on background, you'll get donut-shaped bokehs. That's why I mentioned to you that the images obtained through these mirror lenses can never compare to refractor telescopes, especially the APO ones.