I don’t understand what you’re meaning. My lens is a 28-105, and at 20m, it will be hard to judge of the sharpness if only what I can see is a tiny paper sheet…
Yeah, I guess you’re right about that. I was using a 300mm, so that wasn’t really a big concern with me! 🙂 You could print something like this…
That would give you something large enough to see at a further distance.
I wonder if it can be a good idea if I set my 7D on a tripod and test my two lens on similar focal lengths on the same body?
That would be an excellent idea! That way you’d be able to see first hand the differences in focal length, and sharpness.