I had been told that depth of field will be deeper for smaller sensors. Initially I didn't question this accepting it at face value, wondered whether a MFT sensor might be better for some applications, That is when I started thinking hard and realized the statement might be misleading. I found this page on Cambridge color:
http://www.cambridgeincolour.com/tutori ... r-size.htm
I suspect the person who told me DOF field increases with smaller sensor size may have misinterpreted what was written in that Cambridge color tutorial. specifically this is what is said on that page:
As I understand the quoted section; it is not actually the sensor size that is influencing the DOF but the magnification.As sensor size increases, the depth of field will decrease for a given aperture (when filling the frame with a subject of the same size and distance). This is because larger sensors require one to get closer to their subject, or to use a longer focal length in order to fill the frame with that subject. This means that one has to use progressively smaller aperture sizes in order to maintain the same depth of field on larger sensors.
I now use full frame sensor as:
1. when photographing silver dollar sized coins (aprox: 40mm diametre) coins to fill the sensor with an image of a coin requires less image size reduction(from 1-1).
2. For smaller coins ( some just a few mm in diameter) I can maximize the magnification.
From my understanding it is in the second case where the Cambridge color DOF sensor size statement comes into play( the most). On an APSc sensor I would require less magnification to fill the sensor area with the image, so with the lower magnification the DOF would be deeper than if I tried to fill a full frame sensor( where a higher magnification would be required.
IS my understanding correct? ( I know it seems basic but I just want to make sure I have the concept correct)
would this mean that in some closeup photography situations a MFT sensor might have an advantage over APSc?
I am thinking of the case of using a Melles Griot PN 386080 telecentric adapter ( attaches to a SK 50mm F2.8 enlarger lens). The image circle of that adapter almost fills an APSc frame( but with some nasty degradation on the image edges). I am guessing that on a MFT sensor I might see much better performance from that adapter as it was designed for C mount. I assume with MFT I would require even less magnification so I would see a greater DOF.
This leads to a third question: Might MFT be a better option for coin photography? In my limited experience most coin photographers stick religiously to APSc DSLrs ( being a well developed mature technology that approach isn't wrong)