PIXEL COUNT

[iND]

Answer this:


Given two cameras: 50D (15mp 1.6 crop) & 5D (21mp full frame):


If both cameras are equal distance from the same object, both using the same 100mm lens, and same f stop and aperature.


Which camera will cover the target object with more pixels?

[bob williams]

Assuming the full frame is the target, the 5dII---21 MP.

[neuroanatomist]

The 5D has 1.4 times the megapixels of the 50D, on a sensor that is 1.6 times the area. Therefore, the pixel density of the 50D is higher. Assuming the object in question fits within the frame of the 50D, that object will be covered by more pixels of the 50D's sensor than the 5D's sensor. The only way the 5D would cover that target with more pixels than the 50D is if the object (at that distance and focal length) encompassed an area larger than the 50D's sensor.

[jfritz]

The resolution of the 50D is 4752x3168. Assume that you are photographing object that fills the 1.6 sensor, so you get the full 15mp for the object.


The 5DmII has an actual resolution of 5616×3744. The portion of the frame that is cropped is determined by dividing the horizontal and vertical resolution by 1.6, giving us 3510x2340 -- a smaller value than the cropped sensor.


Thus, the object will cover more pixels of the 50D

[bob williams]

The 5D has 1.4 times the megapixels of the 50D, on a sensor that is 1.6 times the area. Therefore, the pixel density of the 50D is higher. Assuming the object in question fits within the frame of the 50D, that object will be covered by more pixels of the 50D's sensor than the 5D's sensor. The only way the 5D would cover that target with more pixels than the 50D is if the object (at that distance and focal length) encompassed an area larger than the 50D's sensor.






Yep, Neuro is correct--I was thinking full frame of one versus full frame on the other----error on my part

[Colin500]

The 5D has 1.4 times the megapixels of the 50D, on a sensor that is 1.6 times the area.






Erm, if the diagonal is 1.6 times larger, both the width and height are 1.6 times larger, so the area is 2.56 times larger.


(Which figures, the pixels themselves are nearly twice as large on the 5DmkII than on the 50D, and 1.4 times nearly twice as large pixels gives something a bit below 2.8 times the area.)


Surmak's calculation is correct, because it divides both the horizontal and the vertical resolution by 1.6.


The answer to the original question can also be given as follows: If the distance to the subject and the focal length are the same, then, as long as the subject fits within the cropped image of the 50D, the coverage in number of pixels will always be larger on the 50D because of its higher pixel density.


Regards, Colin