StarNut wrote: pKai wrote:
On the 7D, that\'s a whopping 960mm and 1344mm with the 1.4 TC which the 600 takes very well
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 see what you mean. I did some more calculation taking into account the exact pixel (21.1/18) and sensor size (24x36/18x24) differences, and came up with 1.7x pixel density for the 7D (versus the 5D2), which comes out to an theoretical 1.3x crop reach. (Let me know if I didn\'t do that right.)
So 70-300L on the 7D gives a reach equivalent of about 390mm on the 5D2, or pretty close to a 400/5.6 lens. That\'s probably good enough for me.
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.
Jul 28, 2012 at 11:34 PM
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