Do you prefer using low, mid, or high apertures for focus stacking?

Your effective aperture (EA) is the magnification +1 times the lens aperture, so as said above diffraction can begin to degrade the IQ. Like most things it becomes tradeoff between DoF and Diffraction. I do lots of extreme stacking (sometimes ~600), mostly with microscope objectives for high magnifications, and the EA tends to hang around 18~20. These lenses don't have selectable apertures, so you get the EA the lenses was designed around.

Best,

While I don't care as much about diffraction as others do, I think the best answer has already been given - use whatever the sweet spot for your lens is.

mawyatt2002 wrote:

Your effective aperture (EA) is the magnification +1 times the lens aperture, so as said above diffraction can begin to degrade the IQ. Like most things it becomes tradeoff between DoF and Diffraction. I do lots of extreme stacking (sometimes ~600), mostly with microscope objectives for high magnifications, and the EA tends to hang around 18~20. These lenses don't have selectable apertures, so you get the EA the lenses was designed around.

Best,

As Mike notes, it is important to keep the EA in mind if you are doing close up and macro. At m = 1 you loose 2 f/stops so f/11 becomes f/22, well into the diffraction limited range. Nikon chipped lenses give the effective aperture and Canon and most others give the nominal f/stop.

In close up and macro, it is often desirable to have the background out of focus, and a large aperture (smaller f/number) will help blur the background as will a longer focal length lens. In macro, the depth of field at a given magnification is independent of focal length, but the background will be magnified more and have a less apparent depth of field with a longer lens.

IMHO, an intermediate aperture is optimal in most situations. Open up for smoother backgrounds at the cost of more shots, and close down for fewer shots in the stack.

you can get excellent results from one strobe you just need to use mirrors and double diffuse the subject from the light source to give a nice consistent result.

Don

beginner_macro wrote:

I prefer using F/8 for FSing because there won't be any diffraction. But that's only for still subjects; for more jumpy subjects I use F/11 so that if they jump/fly away I have photos with a larger DOF.

With sharper lenses like the Canon 100mm F2.8L, you can go all the way up to F/18 without obvious diffraction. So, for FSing, I'm trying to get the best DOF without introducing diffraction - for me that means F/8 to F/11.

Your analysis is incorrect. Diffraction takes place at all apertures and limits resolution. The diffraction limits are shown below for green light.

These figures are for optical resolution. System resolution includes sensor resolution and the system resolution in terms of MTF is the product of these resolutions. The system resolutions for the 100 f/2.8 L at various apertures on a 24 MP full frame camera have been determined by Optical Limits.com and are shown below.

Maximum resolution in center of the frame is at f/4. Prior to this aperture, resolution is limited by lens aberrations. Beyond f/4 resolution is limited by diffraction and resolution is considerably lower at f/16. Sharpening, preferably by a deconvolution method, can restore some resolution but the image will not have the brilliance obtained with the optimum aperture.