This is one in a series of posts on the Nikon Z7. You should be able to find all the posts about that camera in the Category List on the right sidebar, below the Articles widget. There’s a drop-down menu there that you can use to get to all the posts in this series; just look for “Nikon Z6/7”.
The Nikon Z7 has a feature that has the potential to be useful for capturing images for focus stacking in postproduction. Nikon calls it focus shift shooting, which I’m going to abbreviate as FSS. It works similarly to a feature with the same name that was introduced with the D850. You set the lens to autofocus, and, either manually or with AF, focus it on the nearest part of your subject that you want to be in focus. I use manual focus, and set it a bit nearer than that. Then you tell the camera how many images you want in the stack, and how finely or coarsely the distance steps between each exposure should be made. You can tell it whether you want it to use the electronic shutter or not, and how long to wait between exposures. Then you tell it to start, and stand back while it waits a few seconds for the camera to steady, then does its magic, focusing a bit further away with each exposure. The firmware is smart enough to adjust the step sizes to compensate for differences in lens focal length, subject distance, and lens f-stop.
Used in this application, the Z7 FSS is useful, but has some drawbacks:
- The minimum step size is too large for critical work.
- Selecting different settings for some of the step size selections don’t actually change the step size.
- At the end of the sequence, the camera does not return the focal point to where it was at the beginning, but instead leaves it wherever it ended up. This makes it impossible to simply repeat a set of captures.
- The camera does not show you the captures one by one after it makes them, so you don’t know when to abort the series when the focal plane has gotten sufficiently far away.
The GFX 50S implementation of a similar feature, miscalled Focus Bracketing by Fuji, has none of the above problems.
The Z7 FSS feature is not compatible with my Sigma 105/2.8 macro lens, prematurely ending the sequence after a handful of captures, but it works fine with the Nikon 105/2.8G VR macro. Unfortunately, I like the image quality of the Sigma lens better.
There is another application for cameras that automatically capture sequences with shifted focal planes, and that is focus bracketing for landscapes and subjects that don’t move much. The difference between that and the situation described above is that the photographer intends to select just one image in post, rather than putting the sequence through stacking software. However, the way that FSS in the Z7 and Focus Bracketing in the GFX are designed, implementing that usage is so awkward that it is nearly unusable. To do this kind of focus bracketing, you’d like to have it work this way:
- Focus on what you want sharp
- Press the “go” button
- Camera waits a few seconds
- Camera makes a series of exposures with the focal planes distributed equally in front of and behind where you focused
- Camera returns focal plane to where you focused.
I’m looking forward to that.
For now, I’ll just use it for stacking, and then only when I can’t do what I want with the GFX.