>>2975984Do you realize you gave the answer yourself?
Have some CoC values:
FF: 0.03mm
APS-C: 0.018mm
m43: 0.015
FF:APS-C=0.03/0.018=1.6 (=crop factor of APS-C for Canon)
FF:m43=0.03/0.0.15=2 (=crop factor of m43).
In the formulas posted above, at same relative aperture (e.g. f/4) and the same focal length (e.g. 50mm), is the change in DOF caused by an "equivalent aperture"?
Remember, focal length is determined by the optics, whereas aperture is determined by the opening diameter in relation to focal length. Both are not affected by the CoC. The difference in DOF is caused by the CoC, which then results in the equivalent FOV of focal length X crop factor.
So, technically speaking there is neither equivalent focal length, nor equivalent aperture. However, as the difference in FOV is equal to the crop factor you can speak of an equivalent focal length as a 75mm on FF would give a similar FOV as a 50mm on APS-C.
Still, aperture remains unchanged by that as the effective focal length is still 50mm and only the FOV is changed.
