the 500mm mirror lens is just that ! no surprises here !
if your looking to get close to subjects like wildlife this is a starting point. without going into a photography lesson, f8.0 means your shooting in sunny conditions, or shooting macro with a flash. being that the lens isn't stabilized, I got best results at speeds over 1/320 sec. given the lenses shallow depth of field, shooting continuous burst is a good way to ensure a "keeper". chromatic adoration appears on back-lit objects and the bokeh is a little different, it will turn skinny branches "hollow" because of the central mirror. because the lens is a mirror lens and there is a lack of "glass" this guy is very light, which is a bonus if your packing it around at someplace like the zoo.
after shooting with this guy for a few weeks, i've come to realize that the kit 300mm, or my I.S. 18-200mm with a cropped image can produce beter, sharper images. but at $130.00, it was cheep enough to play with. watch some video reviews (if you can find one in english) and decide for yourself.