I have a Nikon D3100 and desires beyond my funds! With this lens I can take great shots of the moon (that's all so far). Do not expect to take instinctive shots - you need time, a tripod and knowledge of how to set up your camera manually BUT isn't that what good photography is all about? I could only dream of a Nikon lens of this depth and am very happy with what this adds to me repertoire. No, it doesn't get out much, but I don't feel guilty because of the price.
I still have the lens but haven't used it for ages. Now I am more familiar with what DSLRs can achieve, and what quality glass can do, I will no longer use this lens. I now have a D7100 and my main lens is the 18-300mm. Combined with a x2 teleconverter I can get much more stunning and crisper shots of the moon (for example) than I could ever achieve with this Opteka lens. You get what you pay for, so I've dropped from a 4 start to a 3 star rating not any lower as this is a budget consideration for most people.