How good is the Falcon 500 500mm f6.3 ED Mirror Tele Lens for use with the Nikon d3100?

How good is the Falcon 500 500mm f6.3 ED Mirror Tele Lens for use with the Nikon d3100?

It's garbage. There's a reason why "real" lenses of that focal length cost thousands of dollars,)

That lens will have no autofocus and it likely won't meter either. The image quality will be very bad.

Supposedly that's a sample shot taken with one:

(taken from http://cgi.ebay.co.uk/...305110474)

Even at that small size it looks awful, the red letters seem kind of fuzzy and there's heavy vignetting.

They won't be as good as a refracting lens, but they are costing less than 10% of the price, and they don't need a wheelbarrow to transport them ;-)

They probably won't meter on your Nikon, but that's a fault of the Nikon mount not the lens. The problem is the camera doesn't know that the lens is f6.3.

Aside from having only one tiny aperture that is hard to focus even on a tripod and produces lots of foggy foreground objects apart from non-flattering bokeh? If you can bag one at less than $150, it would be fun to play with.