I own a Canon T3 / EOS 1100D. I see that a GP-E2 GPS Receiver works with a T4i but I was was wondering if anyone knows if it will work with a T3 and why or why not? Does the T4i have a certain feature that the T3 does not that would make it work with one but not the other? Thanks a lot.
I believe it will work, but with quite limited functionality.
Basically it is a manual process with the Canon T3. The GP-E2 will capture logging information, but you have to sync the two up on a computer later.
The T4i has firmware that supports the usage of this GPS logger, your T3 does not as far as I can tell. It might be worth looking at any new T3 firmware updates to see if they perhaps have added this functionality since the release of the GP-E2.
This is the compatibility info from the Canon website: