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| p.1 #20 · 5D2 *plus* 7D for extra telephoto reach? |
No it isn't. It's the same field of view on the 7D as a 960 gives on a full frame sensor, but that isn't at all the same thing as thinking that a 1.6 crop sensor has some magic giving lenses 1.6 times the focal length.
"Crop reach," when used correctly, refers to crop sensors with higher pixel density than a full frame sensor. The 7D has a pixel density of about twice the 5d2/5d3, giving it a theoretical 1.4x crop reach (square root of 2), assuming equal image quality at the selected ISO.
I completely understand the math behind the sensor size VS pixel density VS reach issues. For most people that don't live in a lab, this doesn't matter much..... That's not a slam on you, BTW, *I* used to live in a lab coding weather computer models and then I got my sanity back....
I was just trying to present to the OP in simple terms what he will actually see through the viewfinder. He will see a similar FOV with a 600 as a 960mm lens would see. Yes, perspective would not be the same, DOF will not be the same, etc, etc, etc....... that aside, for all practical purposes, a 600 is a 960 on a 7D.
Suresh T wrote:
An extra 7D body isn't exactly light (compared to a Kenko 1.4x), but it won't lose a stop, and will probably also be handy for the times when I need to keep switching between landscape (5D2+24-105L/17-40L) and wildlife (7D+70-300L). I only wish I'd done this before my Alaska trip.
True, but there's much more to the 7D than reach/crop. The AF system on a 7D is much faster than the 5D2 -- fast-moving critters and specially BIF will yield a much higher hit rate than on a 5D2. Then there's 8fps VS 4 and all the 2.0 firmware updates coming in a few weeks.
Congrats on your purchase!