Is there an adaptor that'll get a Nikon fit Sigma lens, on to my Canon body?

I was given a gift of a Macro Sigma lens yesterday, however, it's a Nikon fit. I'm a Canon user. I have no receipt for it, no box with it or instructions. Is there an adaptor of some kind that can get it to fit my Canon EOS without it affecting the lens' ability? I would hate for this gift to go wasted.

Not really.

Any adapter you find will reduce the lens to a manual focus that probably will not focus at infinity. You will also have to manually meter all your shots.

You may want to sell this lens to someone who can use it and buy one that fits your camera

As stated there are adapters, but you will loose AF functions and will will pretty much be strapped to ap and shutter priority modes and will require manual metering. You can find tons or adapters on eBay, if you get one make sure it has glass in it or you will not be able to focus to infinity. Then again even with glass the ratio will not be exactly 1:1

You don't need an adapter with a lens in it for a Nikon lens to Canon camera, only when it's Canon lens to Nikon camera.

The Nikon lens must have an aperture ring, you'll only have manual focus (not a problem with a Macro lens), and you can only use the lens in either Manual Mode or Aperture Priority Mode. Other Modes won't work because the Canon camera can't control the Aperture, Aperture has to be able to be set on the lens.

If you get the chipped version of the adapter you will also get AF confirmation as you do with your Canon lenses.

You WILL be able to focus on infinity. Again it's the other way around (Canon>Nikon) that infinity focus becomes a problem and why a lens is needed for Nikon cameras to get infinity focus when used with other manufacturers lenses. Nikon lenses can be used on ANY other manufacturers DSLR cameras and achieve infinity focus with a simple tube type adapter.

You can get a Nikon-EOS adapter, they actually work quite well if you have an old fashioned Pre AI, AI, AI-S, AI-P or D-type lens with an aperture ring, it will be a manual focus only lens, and you will have to stop down meter in either Av or M mode.

This is the adapter I bought to work with my AI-S Nikkor 20mm f3.5, http://www.ebay.co.uk/...1497.l2649 it fits snugly, but not too tight, and feels good quality.