The camera supports shutter speeds as long as 30 seconds, but to go longer you need to switch to "bulb" mode.
You can find the info here:
http://kbsupport.cusa.canon.com/system/selfservice.controller?CONFIGURATION=1011&PARTITION_ID=1&secu...
You'll put the camera in "manual" mode ("M" on the mode dial) and dial the shutter speed down until it gets to "Bulb".
You'll need to attach a remote shutter release such as the RS60-E3. The RS60-E3 is a simple remote release... it's just a single button (does detect both half-press and full-ress) but it also has a lock switch so you can press the shutter button and lock it so that you're not having to hold it for long periods of time.
You might want to pick up an intervalometer if you want to pre-program capture times (or intervals if you plan on capture lots of exposures over time.) Note that the Canon TC-80N3 (Canon's only intervalometer) has a plug which only mates with their high end bodies (1D X, 5D, 7D/7D II, etc.) and is not plug-compatible with the T5i. You'd need a 3rd party intervalometer (there are lots of them available) if you want a remote shutter release with an intervalometer.
The plug on the remote release looks like a stereo headphone jack.
Tim Campbell
5D III, 5D IV, 60Da
