i have a 70-300 mm lens and a nikon D90. i dont use canon and dont know a ton about photography so i cannot say what a canon equivalent is. zoom in as far as you can and take a crap load of photos. stitch them together and use kmakemultirez. when it sees that it is not a 2:1 image it will ask you some questions about that kind it is before it chops it. rest is the same.