Sorry Denise, I misread your post regarding the 7D. Still, I would think twice about giving up that extra 100mm from the 100-400mm to the 70-300mm. Besides, the cost of the two lenses new is about the same, so you'd lose $ and focal length.


Brant, yes, the crop factor really does affect aperture, sort of. It affects the depth of field, such that you have an apparent aperture of 1.6x narrower on the smaller sensor. In reality, it's still field of view - to get the same framing for a shot with a crop sensor compared to FF, you need to back up with the crop body, and that extra distance translates to deeper DoF.