I would like to make more use of my 500mm mirror lens on my Nikon D50, but it's a pain to use because the D50 was a cheaper camera which doesn't support manual lenses very well. It will only work in full manual mode, doesn't give focus confirmation (which admittedly is not a huge problem, I can generally tell by eye) and doesn't meter or allow aperture-priority automation (which is a total PITA).

Short of buying a better body, the way around this is apparently to fit a special chip to the lens mount, which tells the camera that it's set to an arbitrary aperture and manual focus. Some info about these chips here:
http://filmprocess.ru/nikon_prog_en.htm

These seem to work out around £20 already fitted to a T2 mount, but I'm a bit skeptical of their reliability, they look like the chip would break off if you breathe on it hard. And to be honest my 500mm lens isn't a good one, it may not justify the expense, especially if it's likely to cause problems.

Does anyone have any experience of these mounts?