Will the Lowpro Transit sling 150AW hold a Canon Rebel T3i and an extra lense??
This says for compact DSLR camera, so I don't know if the T3i will fit with this sling or do I need the larger Lowpro 250W Sling?
This should fit your gear. Might require a little finagling depending on the exact size of your camera and lens, but it will fit. I have a Nikon D5500 with a 55-300mm lens in addition to the kit lens in this bag, and some accessories. It's not a perfect fit, but it works.