Can a rebel xti work with a nikon speedlight sb 15?

If so can you help me know how to work it… I'm a beginer with cameras.

No, these are two different systems, Nikon and Canon. You would need to buy a radio trigger to use it as an off camera flash, and this would be only in manual mode. You can get these trigger sets from ebay for about 30 bucks.

Hi

It will not work with the rebel xti, you should buy a nikon if you have the flash already or the otherway around. Best wishes
Rick

It depends on what you mean by "work with". I'm not familiar with that flash. It might actually fire when mounted in the hot shoe of the Canon, but NO automatic functions of the flash will operate. It would have to be set totally manually as to output power, if the flash even allows that. However, the larger problem is that if that is an older flash designed for earlier SLR cameras, it may have too much of what is called trigger voltage at the flash hot shoe contacts. This can destroy your Canon camera.

If you can't buy a proper dedicated Canon flash, then you can still get very effective automatic flashes to use such as the Vivitar 285 HV for only about $80.