Focus-Stacking: Camera Hardware Suggestions
In a previous article, I discussed software to accomplish focus stacking. I glossed over the hardware that lets you get real quality results. I’m going to try to rectify that shortcoming in this article. I’m assuming you’re interested in macro focus-stacking.
For those that are unaware of what focus-stacking is, it involves taking multiple photographs that you combine to get greater depth of focus. Macro photography is famous for suffering from paper-thin depth of focus. Optical physics is against you here, but software and digital photography comes to the rescue.
What you need to accomplish macro focus-stacking is flexible close-up gear. If you check on web sites such as e-bay, and you shoot Nikon, you should be able to locate a bellows setup like mine, the PB-4. I also use rings that let me reverse the lens and attach a filter to the reversed lens. Nikon stopped making bellows hardware decades ago, because the customer base was just too small to make it worth it to them.
Some camera bodies may not allow attachment to the bellows; it depends on how much overhang the “pentaprisim” portion of the camera has. My D610, for instance, barely fits, but the D500 fits fine. Battery grips, however, don’t allow you to connect or properly use the bellows. You may need to set the bellows into ‘vertical-shooting’ format to be able to mount the camera body; crank the camera-mount portion of the bellows to the rear-most position to mount the camera.
I still use the vintage 55mm Micro-Nikkor f/3.5 lens, circa 1974. Think this old lens couldn’t cut it today? Think again. With focus-stacking, you should always set the sharpest lens aperture (f/8 for the Micro-Nikkor). Remember, stacking will take care of depth of focus, so you don’t need to worry about stopping the aperture down to get sufficient depth of focus.
When you get into magnifications greater than life-size, you should reverse the lens to get the best optical results. I use the BR-2 lens reverse ring (52mm). Any other macro lens I have access to doesn’t have the 52mm filter thread, so lens-reversing isn’t an option.
Wind and vibration is the enemy, so you will get best results in dead-calm conditions (such as indoors). I made a custom piece of hardware that fits into the end of my bellows unit; it has an alligator clip to hold small objects at whatever height and rotation I need. This clip hardware is connected to the bellows, so image motion relative to the bellows is virtually eliminated (it would move the same as the camera). The clip can also hold a little platform in front of the lens, allowing you to lay small subjects that aren’t “clip-able” onto the platform.
Lighting is crucial. I often use an LED ring light, which stays cool and provides perfectly even lighting. When my lens is reversed on the bellows, I attach a BR-3 (52mm filter thread) ring to the rear of the lens. I can slip the ring light over the BR-3. The light won’t fit larger diameter lenses. Continuous lighting is really, really nice to see your subject well.
I use a remote or wired release, and I set the camera up in the mode to make shooting a two-step procedure: the first release flips up the mirror and the second release triggers the shutter. Electronic front curtain shutter mode is ideal, if your camera supports it.
I rotate the focusing knob on the bellows to shift the camera/lens combination toward the subject in increments of about 0.1mm for higher image magnifications. I’ll typically take about 50 shots to stack. The zone of sharp focus should overlap from adjacent shots. Be careful to never change the image magnification while shooting a focus stack.
Focus-stacking is mostly incompatible with living subjects at high magnification, since image motion is verboten. Some people claim they can chill insects enough to temporarily stop their movement.
In the demonstration shots below, I found a recently deceased bee and a beetle to use as a subject.
Due to the way stacking works, you won’t want to use tight framing on your subject. Expect to lose about 20% of the image around the edges, which you’ll need to crop out of the final stacked image.
Reverse-mounted lens with ring light and clip to hold subject
I don’t have hardware to reverse my other macro lenses, so the above setup only applies to the 55mm Micro-Nikkor with its 52mm filter thread. This ring light only fits 52mm or smaller diameters.
Note how the hardware that holds the small subject is connected to the bellows; subject motion is no longer a problem in still air. The LED light provides perfectly even illumination without heating up the subject.
For really gung-ho macro photographers, the PB-4 bellows provides both tilt and shift controls to manipulate the plane of focus and also perspective. Focus stacking pretty much eliminates the need to alter the plane of focus, though.
Flash close-ups with AR-4 release, BR-4 diaphragm control
The above setup demonstrates using a flash instead of a ring light. For lenses that cannot be reversed, I use this lighting arrangement if the subject is far enough away. At higher magnifications, the lens will eventually cast a shadow on the subject.
This arrangement doesn’t provide continuous illumination, so the AR-4/BR-4 arrangement can be handy to keep the lens diaphragm opened until you depress the plunger on the AR-4. This cable release was designed for cameras like the Nikon F2, where the second cable would connect to the shutter release.
D500 with wired remote. Subject is lit up.
Focus stack of 69 photos. 55mm Micro-Nikkor at f/8, Nikon D610.
The demonstration photo above was made with the lens reversed and the ring light for illumination. Each shot was made in manual mode, ISO 100 and 1/3 second. You want the sharpest aperture and lowest ISO for this shooting, and please, please use RAW format.
Using good light and an optimal aperture, this stacking technique gives you an idea of just how good the 55mm f/3.5 Micro Nikkor lens is. As I mentioned in another article, they used this lens for shooting the original Star Wars film, with good reason. Film cannot compete with this form of digital photography. I think that focus stacking is the perfect blend of art and science.