Stacking The Deck

Stacking The Deck
A focus stack of two exposures. The foreground leaves and fence at ƒ/8 for 1/3 sec., the background at ƒ/11 for 0.6 sec., and blended manually in Photoshop. Nikon D810, NIKKOR 24-70mm ƒ/2.8, all shots at 36mm and ISO 80

Are you a landscape photographer suffering from out-of-focus foregrounds or backgrounds even when you shoot at ƒ/11? Or are you tired of using ƒ/16 or ƒ/22 to get everything in focus, yet suffering with image softness because of diffraction? Then focus stacking may be for you.

Chances are, you’ve heard of this technique by now—maybe you haven’t tried it or had trouble with it because of the complexity. But with some tips and a bit of practice, you can be on your way to making sharp images at any focal length and angle of composition. It definitely takes patience, yet the process is well worth it if you’re looking for the best-quality images, particularly if you like making large prints and want to retain the sharpest details possible.

So, what exactly is focus stacking? It’s the process of taking multiple exposures at different focus distances and blending them in software to create an image that’s sharp from the closest foreground object to the furthest background object. The process varies from easy to incredibly time consuming and complicated, depending on your level of OCD. It’s fairly often that I have to spend an hour or even multiple hours blending all the exposures, particularly when it comes to landscape astrophotography images that require a difficult blend of a brightly exposed foreground with a dark sky.

Focus stacking is needed in situations where it’s either impossible to get everything in focus in one image or you want to avoid the softness that high ƒ-stops produce due to diffraction. The longer the focal length, the more likely you’ll need to use focus stacking when you have close foreground objects, but even with a 14mm lens you may need to use focus stacking when you’re very close to the ground, making it nearly impossible to get the very close foreground and distant background in sharp focus in the same shot.

Stacking the Deck
Focus stack of four shots manually blended in Photoshop. The sky was shot at ISO
2000 for 30 seconds and the foreground consists of three shots, all at ISO 800, one for
30 seconds and the other two for 60 seconds each. I actually goofed on this and should
have taken at least one more shot for the foreground at a closer focus point; the very
close foreground rocks are actually out of focus. You might be wondering, why shoot at
ƒ/2.8 and not a higher ƒ-stop to capture a larger depth of field? I could have done that,
but I knew I was going to be waiting a while either way since it was dark out, although
the moon was out so it wasn’t pitch-black dark. A higher ƒ-stop would mean a longer
shutter speed to capture more light, although it would result in less focus stacking since
I would have needed fewer shots so, in hindsight, maybe ƒ/4 or ƒ/5.6 would have been
better. Nikon D800E, NIKKOR 14-24mm ƒ/2.8, all shots at 14mm and ƒ/2.8

The absolute sharpest image you can produce with focus stacking requires using the sharpest ƒ-stop of the lens, and then you take as many shots as needed at that ƒ-stop with different focus distances to get everything in focus in the scene. However, for some lenses, this means using a lower ƒ-stop like ƒ/5.6, meaning less is in focus per shot, meaning you have to take more shots for focus stacking. I tend to split the difference and use an ƒ-stop that’s still very sharp but requires less exposures for the stack. I often use ƒ/11 for daytime shots and a much lower ƒ-stop at night to save on exposure times, but you should test your lenses to see how they perform. Every lens model is different.

To see if you need focus stacking with your composition, try using an acceptably sharp ƒ-stop as mentioned above, e.g., ƒ/11 or so, and check the sharpness of your entire frame using Live View mode on your LCD. Adjust the focus until you have everything in sharp focus, if possible. You may notice that when you get the foreground in sharp focus, the background is soft, or vice versa. If that’s the case, then you need focus stacking.

To perform your focus stacking, I recommend starting with either the farthest object or closest object in sharp focus, and then incrementally move the focus and take more shots as needed until you capture everything in the scene in sharp focus in at least one shot. For example, let’s say you’re shooting a sunrise at the ocean with a super-wide-angle 14mm lens and your lens is only a foot off the ground. You may need one shot focused for the foreground rocks, another shot for the midground rocks and water, and a third shot for the horizon. Or you may find that you need half a dozen or more images to get everything in focus; it will depend on the focal length you’re using and your distance from the closest foreground object.

Stacking the Deck
This is the main Focus Shift menu on the Nikon D850. “No. of shots” controls how many exposures to shoot for the focus stack. “Focus step width” controls how much to move the focus ring between each shot. I choose an interval of 0 seconds so the shots are taken immediately back to back. Once you set everything up, click on the “Start” menu item, and the camera will go into automatic mode and take all the shots for the focus stack.
Stacking the Deck
This is the main Focus Shift menu on the Nikon D850. “No. of shots” controls how many exposures to shoot for the focus stack. “Focus step width” controls how much to move the focus ring between each shot. I choose an interval of 0 seconds so the shots are taken immediately back to back. Once you set everything up, click on the “Start” menu item, and the camera will go into automatic mode and take all the shots for the focus stack.

On some cameras, you can set up the camera to perform the focus stacking for you. This includes, for example, the Nikon D850, Olympus OM-D E-M1 Mark II and the Pentax K-1. In the Nikon D850, for example, you can use the Focus Shift mode to tell the camera to capture the stack of exposures for you. You set a step for how much to move the focus between shots and how many shots to take, and the D850 will automatically take shots and change the focus of the lens until it either reaches the maximum focus distance of the lens, or it reaches the configured number of shots.

This menu controls how much to move focus toward infinity between each shot when using the D850’s Focus Shift mode. Start by focusing on the closest object in the frame and then selecting an appropriate step width and number of shots so you can get every part of the scene in focus from the foreground to the background. The step width needed will vary largely based on your distance to the closest foreground object. Scenes with very close foreground objects may require more shots and a lower step width.

Some remote controls can also perform focus stacking with some camera models. Remote control units such as the CamRanger, CamFi or Promote remote control will help automate focus stacking, and the process is the same if a remote controller is helping streamline the shooting process.

Next up, you’ll need to blend the exposures in software. Some cameras can perform the blending of the images in camera, but you’re generally better off doing that work yourself in Photoshop or other software so you have the most control possible over the blend. Some blends are very difficult and can’t be performed by most automated software.

The shots were taken automatically using the Nikon D850’s Focus Shift mode. I focused on the foreground flowers manually using Live View and then chose five images and a middle-range (I forget the exact number) focus-step increment for Focus Shift. I ended up only using three exposures for the focus stack. The foreground flowers consist of two shots blended automatically in Helicon Focus, and the background is one shot that was manually blended in Photoshop into the result from Helicon Focus. All three shots didn’t automatically blend well in Helicon Focus. The boat was moving around in the water, and there was a lot of ghosting because of that. The flowers also had some ghosting issues as well, but using Helicon Focus worked better than Photoshop’s auto-blend mode, and fixing the ghosting problems on the flowers was easier than manually blending them. Nikon D850 sample unit, NIKKOR 24-70mm ƒ/2.8 at 58mm, ƒ/11, ISO 400, 1/60 sec.
Stacking the Deck
This is a screenshot of using Helicon Focus to automatically focus stack two shots that were taken using the Focus Shift mode of the Nikon D850. Helicon Focus has three different blending methods to choose from, and each one is better for a certain type of focus stack. Refer to the manual for details, but for a complex blend like this of the foreground flowers, I find that Method C (pyramid) often works best.

I most commonly use each exposure as a layer in Photoshop and manually blend them together with masking to create the final image. Photoshop also features an auto-blend function that can do the focus blending for you, accessible via the Edit > Auto Blend Layers menu item, but this doesn’t always work. In some cases, the result will be a bit of a mess and you’ll be better off doing it yourself, but in other cases it will work beautifully. Give it a try and see what happens; just make sure to zoom into 100% and pan around the entire image to inspect for blend issues. You may be able to fix them and save yourself the time of a manual blend.

With more complex blends, I sometimes use Helicon Focus, a software program that’s dedicated to focus stacking. Other software packages exist to do the same thing, such as Zerene Stacker, but Helicon Focus is what I’m familiar with. This is what I reach for when I need to blend a focus stack of flowers in the foreground of a landscape photograph. The flowers from one shot to another in the focus stack will be a mess of out-of-focus flowers in front of and/or behind the in-focus flowers, and blending that all manually is a real nightmare. Helicon Focus (and sometimes Photoshop auto blend) usually does a great job of blending the flowers for you. It may result in some ghosting of the flowers and thus require some manual clone-stamping or healing to fix, but it will still be better than manually blending.

Stacking The Deck
Focus stack of about five shots (this was a few years ago, and I’m a little hazy
on the details). The sky was shot at ISO 2500 for 25 seconds. The foreground consists
of four shots, all taken at ISO 1000 for 60 seconds with light painting. I put a white lens
cloth over an incandescent flashlight and waved it over my head during the exposure of
each foreground shot to light up the field of lupines. The foreground shots were blended
automatically in either Photoshop or Helicon Focus (again, fuzzy on the details) so that
the flowers blended more easily, and that result was manually blended with the sky in
Photoshop. Nikon D800E, NIKKOR 14-24mm ƒ/2.8, all shots at 14mm and ƒ/2.8.

You could use Helicon Focus all the time for your blends as well; it’s just a matter of personal preference. Sometimes the blend is easier done by hand instead of fixing the errors of the automated blend. It just depends on the complexity of the blending.

So now that you know the basics of focus stacking, give it a shot the next time you’re out shooting. Find a composition with close foreground objects and try taking multiple shots at different focus distances, and then blend them in software. Try auto blending and manual blending. The more practice you have, the better you’ll become and the easier it will be when you reach those really complicated blends—not to mention, you’ll have sharper images and higher-quality prints. Good luck, and happy shooting. DPP

To see more of Adam Woodworth’s photography, visit his website at adamwoodworth.com.

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