Maximum Depth. Shooting with Stacking or Focus Shift

Have you ever been in a situation where you don’t have the depth of field or just the DOF to fully contain the scene?? Especially landscape photographers who work with wide angle lenses and a “heavy” foreground, in which the objects are very close to the camera, could often face this problem. And it seems like the aperture is already closed to f/22, but the DOF is still not enough. And macro lovers have even more fun: even at f/32 their DOF is only a couple of millimeters. Stacking techniques, often called exposure bracketing or focus bracketing, can help you get the whole scene in.

Start and finish

First, let’s go over the theory. What settings affect the DOF? Aperture? Yes, but not only that. I’ll even say more: it doesn’t have that much of an effect. The greater the effect on the DOF is the greater the focus distance the greater the focus distance, the smaller the DOF and the greater the distance to the subject. It is this parameter which makes the main contribution of the GRIFF narrowing. The AF-S Nikkor 14-24 has a minimum focus distance of 27 cm. And it’s not centimeters to the front lens, but to the sensor, which means the foreground objects will be coming right up into your lens. So, with this minimum focus distance the DOF will be about 10-15 centimeters. Not much, especially if we want to shoot distant mountains and big flowers in the foreground.

By the way, it’s worth remembering about hyperfocal distance – the distance at which the whole scene from the foreground to infinity will be in focus. That’s all cool, but if you want to take a shot with very large foreground objects that will require you to bring the lens very close to them, you’ll have to focus closer than hyperfocus, and the far background will just fall out of the sweet spot. So often a stacked shot will be the only way to get the depth of field you want in the frame.

What is needed to shoot with the stacking distance?. For starters, know what you’re shooting and if you need to use this technique at all. Frame your shot, take a test shot and see what happens. It’s possible that your foreground is not that close to the camera and you can focus on it and get into hyperfocal distance. We’ve got the shot? The foreground is in focus, so is the far background? That’s great, no need to waste time on stacking, you can go shoot something else.

But if you want to focus on something really close, you can’t do without stacking. First, let’s put the camera on a tripod. All frames of the future stitching should be shot from the same point with minimal changes of camera position, or better yet without any. Next you need to focus on the closest visible object. Yes, not on the important subject, but on the visible subject. If something gets out of focus in a perfectly clear shot, it will look messy.

Focused ? Now let’s understand the shooting parameters. I recommend shooting frames for stacking at apertures from 11 to 16 and not going any farther because the farther the aperture is closed the more diffraction you get from the lens which has a negative impact on the quality of a shot. Now you have to turn off autofocus and lock the exposure metering. And it’s a good idea to have a cable switch on the camera so you don’t have to move it unnecessarily. Then you make a shot, move the focus a little towards infinity and make another shot. How “little” you have to shift focus? At 1 or 2 degrees. The longer the lens is, the farther away you need to refocus. It has to do with the fact that with long focus the DOF area is very small, and for effective and high-quality stitching we need the DOF areas of the shots to overlap, and if possible, a lot.

Usually 6-8 frames are enough to cover the whole scene with the 14-24 mm lens. Not bad, not a lot of hassle, you can shoot everything manually. But with a telephoto lens you might need more than 20. Not so easy anymore. Luckily, the Nikon D850 comes with an Exposure Shift function. You set the number of frames and the step between them, tell the camera to start shooting and watch it count down the remaining frames until the series is complete on the secondary display. The camera will stop, either by shooting the whole sequence or by reaching infinity.

Nikon D850, AF-S NIKKOR 70-200mm f/2.8E FL ED VR,

neutral gray filter at 64 units f/16, 3 sec, ISO 64

The series of frames loaded in AdobeBridge, as well as the first and the last frame of the series. See how much the sharpness area varies in these photos. In the first one, only the ice on the foreground was in focus, but the forest was out of focus in the blur zone. On the second one, it’s the other way around

It is important to remember that in order for Auto Exposure Shift to work, autofocus must be enabled on both the camera and the lens, and the camera must be set to single or burst mode. If you have delayed mode set, the camera won’t let you turn on stacked shots.

So you have a series of shots, now what to do with them.

Start by loading all the frames into Lightroom or Adobe Camera RAW. I’ll show you the whole processing process using the last one as an example. But the engines are the same, so you can use this technique in Lightroom. Open all frames of the series and ACR, select them all and process them to your liking. It is very important for us that all frames of the series are exactly the same in terms of processing.

A series of photos loaded into AdobeCamera RAW

Next save the changes, select all the frames in AdobeBridge, go to the menu Tools, Photoshop, LoadfilesintoPhotoshoplayers and wait while the program loads all the selected photos as layers of a file.

Next, we need to overcome what’s called focusbreathing. This is a negative effect, in which frames change their focal length slightly when the focus changes. This effect is the strongest on wide angle zooms, so keep in mind when shooting that you have to sacrifice some information on the edges of the frame.

Let’s get rid of this effect. To do this, we need to select all the layers, choose the Edit menu item and Auto-Align. Alignment settings – on auto. If we shot all the frames from one point without any shift at all, Photoshop will have no problem with focusbreathing and we can go on to the next step. But what do you do if the camera moves too much?? In this case, you may try to discard one of the frames where the deviation from the norm is maximal. But if you have moved the camera too much, the hard manual correction and stitching is ahead of you, which will be individual for every shot and we will not disassemble it here.

Automatic alignment of photos to eliminate the effect of Focus breathing

All photos are aligned. Now you need to select all the layers, make copies of them and combine all these copies into a separate group and immediately make it invisible. Why? You’ll see soon enough.

After that, it is necessary to select all the layers of the stack, go to the menu item Edit, Auto-Blend Layers and in the window that appears, select Stackimages, check the box on Seamlesstonesandcolors and uncheck the item Contentawarefilltransparentareas and press OK. The program will think a bit and will give you a stitched frame with sharpness over the whole field of course, if you have done everything right at the stage of shooting, and you have sharp parts over the whole field of the frame on all your original photos .

Automatic merging of all layers into one with maximum depth of field

And now let’s talk about why we need copies of all the layers. The thing is that if you have moving objects in the frame, photoshop will not be able to handle them correctly and will make a lot of artifacts in the final picture. That’s what we are going to get rid of with our layer copies. In my case we had water moving in the frame. I used a neutral gray filter to make the water softer, and this partly makes our task easier. And there will be a lot to work with. Photoshop got tangled up in the glare and inserted pieces from other shots into the flowing water. To fix this, we open our layer copies and start looking to see where the part of the frame we need to paste into the original file. Then we add a black mask to this layer and carefully draw on it with a white brush with opacity of 100% to those parts that we want to leave untouched in the frame. And so gradually from different layers we restore the corrupted parts of the frame from the original images.

Red marks gluing defects on moving objects and fixing them with layer copies.

Now the resulting pie of layers can be brought together, refined to taste and published to the delight of viewers

The final image, devoid of splicing defects, and its variant after the final color correction