Bower SFDRL14C Macro Ringlight Flash for Canon E-TTL II

Yes, the would be compatible with the Canon EOS Digital Rebel XT DSLR camera, and would fit any Canon lens that has a filter thread size of 52mm, 55mm, 58mm, 62mm, or 67mm with the included lens adapter rings.

Yes.

Yes the Bower SFDRL14C TTL Macro Ringlight Flash (Guide No. 46'/14 m at 50mm) for Canon EOS with E-TTL II is compatible with the Canon SL1 camera.

Not at this time.

Yes, the BowerSFDRL14C Macro Ringlight Flash for Canon E-TTL II is fully compatible for use on the Canon EOS 6D DSLR camera.

It does work with my Canon 5D Mark III, although I use it exclusively with Canon EF 70-300 1:4-5.6 IS USM lens with 58mm thread to exploit its macro ability. It does adequate job, that is it allows me to capture macro photos with on the budget equipment. According to its manual the provided extra adaptor rings are 55, 58, 62 and 67mm, and the flash itself has a 52mm thread, so it seems you may have to look for the 77mm adaptor separately. The other question is, how much of the view of the lens will you lose, when putting 52mm diameter ring flash on 77mm diameter lens. I am not sure how the loss of the extra field would affect your work, possibly not at all, I just don't know. I hope this answers your question.

The Bower SFDRL14C Macro Ringlight Flash for Canon E-TTL II is compatible for use on all Canon EOS DSLR cameras, including the Canon EOS 10D DSLR camera. The Bower SFDRL14C Macro Ringlight Flash for Canon E-TTL II fits any Canon lens that has a filter thread size of 52mm, 55mm, 58mm, 62mm, or 67mm with the included lens adapter rings.

If the 70d has a hot shoe it will work. Check the size of the lens you intend to use it on. Then check the adaptor sizes. Not all sizes come with the ring lite. But they can be purchased separately.