Focus stacking might sound like a complicated concept in photography, but it is much simpler than it sounds. This article will make what it is and how to do it yourself extremely clear! Focus stacking means essentially combining multiple images with different focuses to produce a photo with a much higher depth of field than if those images were seen individually. But there is so much more to understanding it than reading a simple definition, be sure to keep reading to know how to execute this yourself.
Why do you need to do it?
This is often the first question people ask me when I talk about focus stacking. Why do I need to stack photos when I can just choose a small aperture such as f/22 especially when using a tripod?
The first and most obvious scenario is when you are photographing a scene where you have something very close to your camera and also an interesting background. You want to capture both sharp and in focus. Depending on the distance between them you may not be able to achieve focus on both a small aperture. But also, extremely small apertures (f/18 or smaller) can often have a detrimental effect of image sharpness. Most lenses have a sweet spot (where the lens produces the sharpest image) which is usually found two or three stops from a really wide-open aperture. If you can stack photos using the sweet spot it will result in a much sharper image than using extremely narrow apertures.
Another reason for using focus stacking is that there may also be times when the conditions won’t allow the depth of field that you want shooting handheld. For example, if you don’t have a tripod and there isn’t sufficient light to allow you to choose a smaller aperture, the shooting with a wider aperture and focus stacking might give you the result you want. Granted this can be tricky as you need to try and keep your camera as still as possible, but it can be done.
When focus stacking your images, you must have specific equipment to do the job most successfully. First, you will need a tripod to enable the individual images shot to be of the best quality and without movement of your camera. The camera used to do so must be able to shoot manual mode to allow to avoid the camera automatically changing settings. Finally, you must have access to editing software that specializes in the ability to focus stack (like Photoshop) where layering images in a photo stacking formation is possible.
How do I do it?
The key for focus stacking is to try and keep your images as similar to each other as possible. So that means keeping your composition exactly the same (hence a using a tripod) and capturing the multiple shots as quickly as possible to avoid lighting and weather changes. Ideally, you’ll need to avoid elements coming into your shot as well such as cars and people. So as you can imagine this can be tricky when photographing busy cities. Landscape photography and macro photography are the two genres of photography that are most suited to focus stacking.
Essentially, you need to capture your image with different focal points. Aim for a minimum of three shots but you can take more. You should try to capture a shot where the focus is on the foreground, one which is around midway in your scene and one which is in the distance. When combined, you will produce a photo with a much greater depth of field than an individual shot.
Macro photography focus stacking
One area of photography that focus stacking is really useful for is macro photography. Macro photography involves a very shallow depth of field. So if you miss the correct focus point even slightly your image will seem blurred. By focus stacking your shots, it gives you a degree of being able to get a longer depth of field.
As stated above, ensuring that you have the correct equipment will go so far in determining your images’ success. A tripod is a must for macro photography and you should make sure that you set up your tripod securely to avoid it moving in between shots.
Once this is done, position the camera to allow for your main focal point of the subject of your image. For example, for insects, this might be the head. Now, the important part is to make sure you don’t change your settings or zoom in or out in between shots so set your camera up on manual mode. You’ll probably find it easier to have live view on rather than looking through the viewfinder.
Once you have taken the first shot, move the focus point further away in increments. It might be worth doing this at set intervals, so you don’t move too far or too close each time you take a photo. Keep in mind that in macro photography your focus point will only need to move in millimetres.
Keep going until you feel that the depth of focus has been fully satisfied. This will depend on the subject being photographed but a good rule of thumb is to keep going until you have covered the totality of your subject.
Landscape focus stacking
Now that we have covered macro focus stacking, let’s look at landscape focus stacking. This is another common scenario for using focus stacking. You may want the whole image to be focused, both the background and the foreground. Take the example of a person standing near the camera with a gorgeous mountain range behind them in the distance. Even at small apertures, the mountains may not be in focus.
Just like in macro photography make sure your camera is set to manual mode and it securely placed on a tripod. Once done, set your camera to a live view and focus on the nearest point of interest to your camera. Zoom in on your LCD screen and precisely focus your shot. Then move the focus point mid-way from your subject (remember not to zoom in or out) and refocus on this midway point. Finally, focus on the furthest point and repeat! You can, of course, take more shot if needed but generally, three should be enough.
Stacking the final image
There are lots of software that you can use to stack your images. I use Photoshop which makes it incredibly easy. Here’s how:
- Open Photoshop
- Click: File => Scripts => Load Files into Stack => Browse
- Select all of the images that will make up the stacked photo
- Click OK and the images will open in Photoshop on separate layers
- Click Edit => Auto-Blend Layers
- Choose “Stack Images” and ensure “Seamless Tones and Colors” is ticked
- I also tick “Content Aware Fill Transparent Areas” but this is optional
- Click OK
This should blend all of the images into a single image using various makes on each layer. The final step is to flatten your image (Layer => Flatten Image) and then save it. Please note that flattening the image combines all the layers into one photo so if you want to keep the working file with the layers on, save it as a PSD file before flattening. You can then save a copy as a flattened JPEG or another file format if you wish.
There you have it. An easy to understand guide to a really common technique that is used by photographers. Remember that the most important element in this process is making sure that your composition remains as similar as possible between your shots.
Photo credits: Kav Dadfar – All rights reserved. No usage without permission. Dreamstime.