Why won't my canon eos 2ti focus when using remote.?
Frank: There are two remotes for the T2i
There are two remotes for the T2i: The infrared RC-6 and the hard-wired RA-E3. Plus, there are after market versions as well. Which remote are you using? Did the remote ever focus the camera in the past, or did you just get it and are wondering about the AF? With some remotes, if you press the button half way, then the camera will focus. If you're using the IR remote, then there's a setting within the T2i that will allow you to change whether the IR remote activates the AF system or not. Strongly recommend that you read the manual for your remote. Go on line and do a search for the manual. Press Ctrl + F to open the find window within your browser. Enter "auto focus" in the search window to find all references to auto focus within the owners manual.
There's a setting buried deep within the T2i's menu system that affects remote control. Either brute force your way into the menus one by one or look into the manual to find it.