|Quoting fedeleal (Reply 4):|
linear meters/ft does each lens zoom in at its max?
What you are asking has no answer. When at any focal length the lens has a field of view so what can be seen in the field of view depends on how far away it is - a C172 closer will fill the viewfinder like an A380 much further away.
A better way of looking at it is how far away will the [pick a plane] be to fill the viewfinder/image at 300mm and 400mm - not forgetting the 7D is an APS-C camera so there's a 1.6x crop factor which means you're looking at 480mm and 640mm in 35mm terms
At 300mm (=480mm) the horizontal angle of view is 4.29deg
At 400mm it's 3.22deg
An A320 (length = 38m) would be 500m away to fill the viewfinder at 300mm and 675m away with the 400m lens.
An f18 is 17m long, just less than half the A320, so the corresponding distances would be 250mm and 340m or thereabouts.
A lion is 2m long so the respective distances would be 30m and 40m.