Is my thinking about equivalence right?

Started 3 months ago | Questions thread
RSTP14 Veteran Member • Posts: 5,040
Re: Is my thinking about equivalence right?

bobn2 wrote:

Olympus has to produce double the resolution of the Sony just to match it in a final image, due to being magnified twice as much, then there's not much of a comparison. You have to compare the Olympus lines with the lined for half the lp/mm on the Sony. On FF 10 lp/mm corresponds to 215 lp/ph, whilst on FF that final resolution is given by 20 lp/mm, so if we compare the two at the same final resolution, we find that the Sony gives an MTF of 0.93 in the centre and 0.85 at the edge, whilst the Olympus gives 0.77 in the centre and 0.69 at the edge.

You can't talk "magnification" with a digital sensor like you do with a film substrate. On a digital sensor the number of pixels, or data points you may want to call it, defines the size of the image, not the size of the sensor itself. Hence a sensor 1/2 the size with twice the number of pixels will produce an image twice larger when viewed at the same "magnification". This is where I don't understand when magnification is used as a variable to compare DoF between different sensor size. It has no relevance in a digital world, rather the total number of pixels that makes up an image does.

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