I recently purchased a Canon SL1 as a second camera to my Canon 70d. Today I had my first shoot, and I noticed something weird with the exposure. Both of my cameras were set to 1080 24fps, 50 shutter speed, 2.8 aperture, and ISO 200. However, the Canon Sl1 was underexposed. To create the same exposure as the Canon 70d, I needed to bump the SL1's ISO to 400. Shouldn't camera's with the same settings reproduce a similarly exposed image?