Focus Stacking

Do you find yourself shooting in difficult conditions, where your ambition to create a beautiful clear, sharp and focused image is compromised by noise? Is blurriness getting in your way? Or is your scene too dark for a high aperture? Generally, in photography, our decisions are limited between the triangle of ISO, shutter speed and aperture. Increasing one reduces another in a blend that can create some incredible effects, but sometimes just isn’t quite enough. 

Focus Stacking – What is it and when to use it?

Perfectly infinite depth of field is one of those things that is not possible to produce from a single image. With the help of multiple shots and some computer magic however, it is possible to enhance and create perfect focus through the entire depth of an image. The technique is called focus stacking, and as the name suggests, requires taking multiple images and stacking them on top of one another. 

Focus stacking is an appropriate technique for two instances, landscape photography when the subject is very close in the foreground, and macro photography, where even small changes in the depth of an image can result in significant changes in detail and focus. 

A key thing to consider when developing a  focus stacking composition is the lens that you will be using. The longer the focal length of your lens, the shallower the depth of field. Focus stacking is, therefore, a more relevant technique when shooting landscapes with a telescopic lens. The effects, when used in these instances, can be stunning as the foreground and background are already flattened by the long lens, having them both in perfect focus can create a truly beautiful image. 

Focus stacking can still be relevant for images taken with a wide angled lens, however. Check out this example of some spring flowers I took a while back.

Focus Stacked Image

In this example, the subject of the photo is close to the camera whilst the background is far off in the distance. Even with the long depth of field created by the wide angled lens, both the foreground and the background couldn’t be in focus at the same time. This image had to be created using focus stacking. 

There are a few techniques you can use to judge whether you are going to need to use focus stacking to craft your perfect image. I checked whether this image would work without any computer adjustments or enhancements by setting my aperture as small as the light would allow and focused roughly 1/3 towards infinity. I took the shot, and then went back, zooming in on the image in the back of my camera to discern whether there were any problems with detail. 

It’s a simple check that I’m glad I did, because I wasn’t quite happy with the sharpness of the image, meaning I knew that I was going to have to use focus stacking. 

Here’s a similar image where you can see the difference.

Image Not Focus Stacked

Notice how the mountain range in the distance doesn’t have the same detail as in the other image? Compare these two images together to see the difference that photo stacking can make.

Okay, so you’ve seen the difference that focus stacking can make, so the next question is, how do you do it?

Taking the shot

Firstly, you’re going to need a tripod. It is absolutely essential that your camera does not move in between taking each picture, otherwise, when you get your shots back to post, they’re not going to line up and it’ll be a struggle to edit them together. Also, if possible, you’re going to want to set your camera to live view mode here, as it will allow you to assess the focus of your shot more easily and make it less likely that you will move the camera.

Once your camera is on its tripod and you’ve framed your composition, the next thing you’re going to do is focus on the closest piece of foreground that you would like to keep in focus. Change your settings to manual to ensure that they don’t change between taking each image. Make sure you have everything just how you want it and take the shot. 

Next, adjust your focus ring take another shot focusing mid-way into the composition. And finally, repeat this step focusing on the background of the composition.

Simple enough, you have now captured the three images that you will use for focus stacking, the rest will all be done back at home, on the computer with photoshop. 

Keeping with the example above, while I should have taken more time and done three levels of focusing I was in a hurry and only did two. You can see them below. These images are Straight Out of Camera (SOOC), meaning they have not been edited.

Post Processing 

When you get back home, the first thing to do is open up your images as layers in Photoshop. Have your first image with the foreground in focus as your first image, the mid-focus image as the second and the final image as the third. While the order of the images isn’t important to Photoshop, I do like to keep my layers organized so when I return weeks or months later it’s easier to remember what I did. There are numerous tools within Photoshop to auto-align and blend the images. 

So the steps are 

1. Load all three images into different layers in photoshop 

2. Select all of the layers 

3. Head to the edit drop down and click “Auto-Align Layers”

   1. Select “Auto” and click “OK”

4. Go back to the edit drop down and click “Auto-Blend Layers”

   1. There are two boxes, click the one labelled stack images. We don’t want to create a panorama.

   2. Go ahead and click OK

5. And that’s it! You can then take that image and run it through your normal workflow. 

I understand that photoshop can sometimes look huge and complicated and incomprehensible. The trick is to tune out what you’re not looking for and follow the instructions, the tools are there to really make your life easy!

Finishing up

So, there you have it! A complete guide to shooting and compiling focus stacked images. Not too difficult when you know how. Hopefully, this technique will allow you to start playing and try some new compositions that you were not able to do before. The two most important things to remember when taking focus stacking images are always bring a tripod and have your camera in manual when shooting. Getting these two things right will ensure you will have a correct exposure that is nicely aligned for when you get back to your computer. 

So that’s a wrap…

Well, that’s a wrap for this week, as always if you would like to find out more about different techniques feel free to check out the dates of my photography workshops and meetups where we can get together and talk about all different aspects of photography. If you’re already heading out and taking some shots yourself, feel free to post them in the comments section below! I look forward to hearing from you.