Quote:
|
Originally Posted by jfrancho
DOF will be greater with a full frame camera, if all else is equal.
|
I'm not quite sure how true that is when you get into macro territory (and by macro, I'm using the traditional 1:1 magnification or greater definition). What happens with Macro and a cropped sensor is that you get less image at 1:1 because the sensor is smaller. You are going to have the same distance between camera and subject at 1:1 with a given focal length lens, no matter what the film/sensor size. It is just that with a full frame 35mm size sensor you fill the frame with something that is about 1x1.5 inches. On a smaller sensor camera at 1:1 you will end up cutting off the edges of a subject that size.
The camera to subject distance has not changed. The magnification is the same. I think the DOF should be the same.
Many people now call "close up" photography "macro." They just mean that you can focus on something less than 10X the focal length away from the camera, even if it is less magnification than 1:1. There you may find differences in DOF because you are actually getting less magnification with the cropped camera to get the same field of view.
Macro lenses do NOT have less depth of field that "normal" lenses. They may be better corrected for work at closer distances. They may have a flatter plane of focus. But those don't change DOF. The shallow depth of field in closeup/macro work is because of higher magnification. And you would get the same DOF with a "normal" lens and extension tubes or closeup lenses.
And at 1:1 the DOF should be the same with a 50mm lens, a 100mm lens, or a 180mm lens. But there is actually a situation where the longer lens would give you MORE depth of field. This has to do with the construction of the lens and entrance/exit pupil sizes. I'll try to find a reference to that and give a link in a follow up message.
Just more stuff to think about....
John