"Crop-ability" of images?

Started 3 months ago | Discussions thread
Bassam Guy Veteran Member • Posts: 3,036
EZR way

dperez wrote:

More photographers who’s judgement I respect are talking about moving to Olympus. A question came up the other day and I’m trying to figure out the answer.

Nikon D850, 600mm f/4 versus M1X, 300mm f/4.

As I understand it - the lenses are the same equivalent - 600mm. The Nikon shoots at f/8 and ISO 3200 and 1/500. The M1X shoots at f/4 so the DOF is the same, and ISO 800 and 1/500, so the exposure is the same, right?

Go outside and shoot a backyard bird. Same spot, same distance, same bird, both cameras.

On EACH sensor does the bird take up approximately the same percentage of the sensor? On the D850 image the bird’s head covers about 20% of the width of the sensor. Does the bird’s head cover the approximately the SAME 20% of the sensor on the M1X – within reason since one is a 3:2 sensor and the other is a 4:3 sensor?

If SO, the bird’s head is 20% of 5184 = 1037 px on the M1X and 20% of 8256 = 1651 px on the D850. Based on that, the subject in the D850 image has 60% more pixels available for cropping. What am I missing?

Of course, a sensor with more pixels, regardless of physical size, will have more "crop-ability".

Better to use area rather than a single dimension. No reason to go to all that math. The "close enough" ratio is 45mp / 20mp or 2.25:1.

 Bassam Guy's gear list:Bassam Guy's gear list
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