What is the correct way to estimate the minimum magnification (maximum subject distance) at which features of a certain size are resolved?
My thinking is that given a system capable of resolving a certain number of line pairs/mm you should be able to estimate the point where certain features are no longer resolved by doing the following:
1 / (lp/mm) = minimum feature width on sensor
minimum feature width on sensor / desired object space feature width = minimum magnification
As an example resolving individual hairs on a Canon 7D where the sensor is the limiting factor:
1/(104 lp/mm) = 9.62um at the sensor
9.62um / 100um (avg human hair) = 0.096x minimum magnification
Applying this to the approx sensor size (22.5mm x 15mm) we can state that we shouldn't expect to see individual hairs in an image with a object space field of view greater than approximately 235mm x 156mm.
Am I missing something? Or is my reasoning generally correct?