To stack or not to stack

John K wrote:

gardenersassistant wrote:

gardenersassistant wrote:

There was no extra DOF from the smaller sensor.

Following on from that ...

Beyond a certain magnification (which varies depending on the kit used) it is possible to get greater DOF using a single capture with an interchangeable lens camera than from a fixed lens camera with a much smaller sensor. The greater the magnification, the greater is the difference in achievable DOF.

I think that what you are saying here is counter intuitive.

I put "(not a typo)" in the title precisely because I thought the idea of getting greater DOF from a larger sensor would be counter-intuitive to many people.

Depth of field is strictly a combination of magnification and aperture.

Yes.

The magnification does not change simply because you are using a smaller sensor.

Yes, and I didn't say that it does.

Using a smaller sensor means that you can fill the frame with the subject at a lower magnification than using a larger sensor.

Yes. (As was demonstrated with this example. The magnification was around 12:1 for the FF camera and the magnification needed to fill the frame with the same scene was around 2:1 for the 1/2.3" sensor.)

Using a lower magnification means more depth of field.

I would like to know the context you are thinking of here. It seems to me that, as stated here, unqualified, as a universal statement of fact, that statement is demonstrably false.

In the current example the much higher magnification produced much larger depth of field.

My previous example showed pairs of images of the same scene captured with cameras with different sensor sizes. The magnifications were therefore different. The depths of field (in both cases the maximum depth of field obtainable, obtained by using the minimum aperture available) were the same. So in those cases lower magnification gave the same depth of field.

What are the circumstances you are thinking of whereby lower magnification gives greater depth of field?

Macro photography is defined as projecting a 1:1 scale image (life size) to a 10:1 (10x) scale image of the subject onto the image plane.

Yes as to the image plane aspect of this. As to the 1:1 to 10:1, that is one definition of macro, although interestingly enough it means that the FF image in the current example is not a macro, while the image from the 1/2.3" image is. Personally, I don't see that distinction as being particularly helpful in this case (and in a lot of other cases, particularly where small sensors are involved).

Notice how the size of the image plane does not factor into that definition...

Yes.

It's important to keep the definition of what is and what is not a macro image a standard across the different sensors,

Yes.

otherwise it becomes impossible to discuss the difficulties in lighting the subject and the limited depth of field at 1x and higher mag.

Yes.

No matter how much you want the sky to be green, it will always be blue...

I think that statement is unnecessary and unhelpful. The only way I can interpret it is as being intended as an insult, which seems to me to be uncalled for.