Crop calculator

Started Oct 18, 2009 | Discussions thread
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Crop calculator
Oct 18, 2009

The 18MP from a 7D has a huge crop potential. Is it mathematically possible or is there an online calculator that will help me determine crop equivalency? For example:


Body (FF or 1.6x)
Input MP
Lens focal length
Desired Crop focal length (to get cropped FOV)


Crop MP
Crop aperture (assuming crop is centered)

What the above calculation should give me is the size in mega pixels I would get if I cropped an image taken with a certain focal length lens/body to mimic the field of view of another focal length lens. Obviously the "perceived" aperture would also change.

So if I took a 18MP image with a 300mm f/4 lens, how many MP/f would i get if I were to crop it to get a 800mm FOV. Maybe 6MP f/11?

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