Z7ii with 105 s macro lens focus shift question

What would be a good setting for focus stacking individual flowers— f stop,  how many frames, what width? I’m finding that I run out of depth before I get to the back of the subject, leaving the back out of focus. I can do it manually, but would prefer the automatic option.

Billstek wrote:

What would be a good setting for focus stacking individual flowers— f stop, how many frames, what width? I’m finding that I run out of depth before I get to the back of the subject, leaving the back out of focus. I can do it manually, but would prefer the automatic option.

None of this is well documented, but I use the following rule of thumb for close up photography (not for macro photography).

I assume that a step width of 1 is about 1/8 the standard depth of field calculated from the standard circle of confusion (CoC) of 0.03. So all you need is a DOF calculator and you can calculate how many step sizes you need to get a certain depth.

If your flower is 3" tall and deep, then the image will be 4" tall at 1.5 feet and you will want a depth of 3" to capture it. This is for a 105mm lens, and is proportional so if you want an image that is 8" tall, the distance would be 3 feet.

Use a DOF calculator to calculate depth of field. This is dependent on focal length (105mm) and aperture. An aperture of f/8 will provide sharp images with significant DOF. You can go with smaller f/number (f/5.6), but then you need more images. You can go with larger f/number (f/11), but then you get less sharp images with diffraction.

The DOF with 105mm lens, f/8, at 1.5 feet is 0.3".

The number of steps needed is

StepNumber = Depth / DOF / StepWidth * 8

Or 3" / 0.3" / 1 * 8 = 80 steps.

But do you need a step size of 1? I tend to use a step size of 3 for standard full frame like the Z6ii, and a step size of 2 for high resolution sensors like the Z7ii. For crop sensors I adjust the CoC by the crop factor.

There is a useful online calculator here:

https://www.pointsinfocus.com/tools/focus-stack-calculator/#comments

In the field, it is easy to adjust these calculations to compensate for changes. All you need to remember that the DOF at f/8 and 1.5 feet is 0.3". If you change aperture, the DOF changes linearly with f/number (at f/16, it is 0.6"). If you change distance, the DOF changes with the square of the proportional change in distance (at 3 feet, it is 4 times as large, or 1.2").

So, for a 3" flower, I would focus at 1.5 feet and use a step width of 2 and 50 steps (fudge the 40 steps I calculate just to be conservative).

Wow, thanks for your in-depth reply. I’ve just been winging it— trial and error. Hopefully this will speed up and improve my results.

Billstek wrote:

What would be a good setting for focus stacking individual flowers— f stop, how many frames, what width? I’m finding that I run out of depth before I get to the back of the subject, leaving the back out of focus. I can do it manually, but would prefer the automatic option.

Johns reply gave you a formulaic method.

I think fuji allows you to set front and back focus points and it does it for you (I'm not a fuji user but that was implied on a thread for the new xt5).

I prefer a touch of trial and error, ie try something and then adjust based on the results

So depending on how OOF you want the background I'd start with f3.2-f4. Keep step size small (eg 2-4), and start with 20 shots and depending on where the last frame ended increase as needed. My other post today used 90 steps and it could have done with 10 more, if the shots go beyond where you need you can delete the unwanted frames

Experiments are fun too

Jim

Another way of looking at things-- always a good thing! Thanks!