ebay fisheye

i was thinking of buying this fisheye off ebay and i was wondering about this part : To achieve a Circular Fisheye image, the focal length of the camera's lens must be about 35mm or shorter (equivalent of 35mm film format). Otherwise, it may not make a complete Circular Fisheye image. Cameras with 4/3 type sensors can shoot a Circular Fisheye picture but not a Diagonal Fisheye image. It is recommended to take trial shots at various focal lengths to see the exact effect with your camera and lens combination.

could someone tell me if i will get a decent fisheye image if i put this on the nifty fifty or the 18-55 kit lens with either a 40d or a 400d


also what is the difference between circular and diagonal fisheye

Circular fisheye is a full circle with what in any other lens would be severe vignetting. There'll be a circular fisheye picture in the middle of the frame and black around it. A diagonal one will fill the entire frame; ideally covering 180 deg. on the diagonal.

And that's going to give you a so-so image, as most add-ons do, but it's a good deal less expensive than a real fisheye lens would be.

I have a lens that looks exactly the same as this item (different make tho .. also made in Japan).
I bought it back in the '70s and used it with my AE-1 and 28mm wide angle lens. It gave quite reasonable results and gave some close to fisheye shots (circular image with black circle around it).
Drawbacks are .. it will degrade to image, and it is limited to a max of 58mm thread size (altho you can use step-up adapters to fit your filter size). Also, it's fairly heavy and I could see it would put strain on the zooming mechanism of a cheap 17 - 55 kit lens.