Shot with an 800mm Nikkor AIS lens at f8
Nikkor to Canon Adapter Mount.
Full-Frame - 21.5 megapixel image RAW
1/1250th second - 1 frame every 2 seconds - Intervalometer controlled.
Tripod mounted.
A series of images of the full lunar eclipse from April of 2014.
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There are many affordable used lens alternatives - especially for Canon owners. The Canon EOS lens mount is particularly wide and the FFD - Flange Focal Distance (the distance from the back element of the lens to the film plane - needed for proper focus) - allows for the use of many non EOS lenses.
I have several T-mount (telescope mount), M42 mount (developed by Zeiss and popularized by Pentax - sometimes called a Pentax screw mount), and Nikon F-mount lenses that I use with my various Canon bodies.
Adapters which set these lenses to the correct FFD are readily available and very affordable.
If you are shooting in a situation where quick focus changes are not required (because these lenses will all only work as full-manual lenses) - they can be a life-saver.
Regarding crisp images - the shots of the moon should prove that you can take a $25 pawn-shop lens and so long as the optics are clean (no mold or deep scratches) you can get some stunning photos.
The last image of this card was shot with the same $25 pawn-shop 800mm f8 lens and camera body that the moon photos were shot with.
I think that image is clear and sharp enough...
You do want to make sure that whatever old lens you purchase and mount to your camera isn't going to sit too deep in the lens mount adapter and hit your camera's mirror as the mirror moves up for the exposure.
I've never had one that would - and I have over a dozen old lenses for environmental/landscape photos, studio photos and cinematography applications now.