#1. "RE: T2 mount lens on Nikon d5000" In response to Reply # 0
It is possible, but it's hardly worth the effort. This lens is worse than bad - it is literally the worst "lens" I've ever used, and not by a small amount. There are mediocre lenses, and then there are bad lenses - and this one is one of the latter.
It is safe, in that it won't harm the camera. (It will only harm the images.)
Exposure is 100% manual: turn the exposure mode to M, and then you are responsible for setting the appropriate shutter speed and ISO. (Aperture is fixed at f/8 on this lens, there is no diaphram or aperture control due to the reflex design.) It is not so tough to use the histogram to correct any error, although of course this is not so good in fast-moving situations.
Focus is 100% manual (it's not an AF lens). I find that this is quite difficult without an expensive aftermarket focusing screen (KatzEye with OptiBrite - $245). I can also assure you that the unsharp results I mentioned at the top are NOT the result of bad focus: nothing in the frame is sharp enough to look like it's in focus. I published some comparisons in this thread.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!