To stack or not to stack

John K wrote:

gardenersassistant wrote:

Here are a pair of images captured under more controlled conditions. I set down a line of tape on a table and mounted a light coloured plastic rule at an angle to the tape and a metal rule perpendicular to the tape, as shown below.

I captured an image with two cameras, placing each camera on the table and using the line of the tape to help me align each camera so it was as best as I could make it head on to the metal rule and therefore at the same angle to the plastic rule. The vertical angle on the scene varied a bit as the cameras and lenses were of different sizes and shapes and needed to be differently supported so as to be able to frame both rules.

Here is an uncropped image captured with a Panasonic FZ330 camera, which has a 1/2.3" sensor, with the f-number set to its maximum f-number of f/8, and with a Raynox 250 on the camera lens.

Here is an uncropped image with the same scene width of 12mm captured with a full frame Sony A7ii with a Meike 60mm macro lens with a 2X teleconverter, a 1.4X teleconverter and 68mm extension tubes. The f-number was set to f/22.

The image captured with the small sensor FZ330 using its maximum f-number of f/8 (and therefore giving the maximum achievable depth of field for that setup) has less depth of field than the image captured with the full frame sensor A7ii.

OK, that's fine. But the smaller sensor isn't causing the drop in depth of field, the limited maximum Fstop is.

Correct.

Why was it necessary to add two teleconverters and extension tubes to the 60mm macro for the full frame shot? Did it really take all of that kit just to get to 3x (36mm wide sensor / 12mm)? Seems like just the TCs would have taken that lens to 3.4x.

The 60mm macro was not at 1:1. The idea here was to illustrate that a full frame with extensions could have more depth of field than a small sensor camera using maximum f-number. I added all that extension so as to get a clearly visible increase in depth of field.

With the 60mm at 1:1 it looked like this, scene width around 5.5mm, around 6.5:1.

I used less magnification than this so we could see more of the mm marks on the inclined rule so as to make it easier to compare the depths of field.

If I'm getting the specs right the 1 2/3" sensor is 6.17mm wide, so that shot is about 1/2 life size.

Correct.

And around 3:1 on the full frame, which exemplifies the reason I have reservations about the 1:1 to 1:10 definition of macro. It means that the first of the inclined ruler images above is not a macro and the second one is, even though both cover (roughly, because of the different aspect ratios) the same field of view.

To avoid the confusion (and around here at least, the arguments) that can arise over the 1:1 definition I tend to talk in terms of scene widths when comparing kit, and tend to refer to my images as close-ups, even when they are of rather small subjects like springtails and barkflies. (Unlike the problems that can arise when using the term "macro", no one has ever objected to my use of "close-ups" for images they would define as macros.)

It depends on the context. Around here you sometimes have to be rather precise about things in order to (try to) avoid contention. In other places I find it works fine to talk about my invertebrate images as macros in contradistinction to my botanical images which I refer to as close-ups, even though most of my small sensor invertebrate images are not macros according to the 1:1 definition.