There will be times when you will need to get something entirely in focus. This is where focus stacking comes in.
This article is about how to use focus stacking to capture those sharp images.
What Is Focus Stacking?
Focus stacking involves ‘stacking’ together images to achieve a larger focal length. The images will have different focal placements.
When we use a wide aperture (f/1.4), the focal length is at its minimum, covering a very small part of an object. This is great for singling out and forcing attention on a very small area, but sometimes we don’t want that.
You’ll take several images where the focus hits a different part of the subject. This way, you can create a final image where the entire subject is in focus.
Why Not Use a Narrower Aperture
Why don’t you use a smaller aperture (f/16), you ask? Well, a smaller aperture would, in fact, place the entire subject in focus.
But it might also place the focus on a distracting background. By using this method, you are selecting the areas you want in sharp focus or your focus point. Everything else stays out of the limelight.
Also, consider the light conditions and relative distance to your subject. You might need a wider aperture.
A wider aperture lets in more light. This keeps your ISO down and your resolution and image quality at their highest.
What’s the Ideal Aperture
For stacking photographs, the ideal aperture of your lens is around f/5.6 or f/8. These focal ranges as their optimal area.
Above and below this number, you may find aberrations.
Even with these apertures, using a macro lens will mean that not everything you want will be in focus. You will still need to stack your images for an optimal focus length.
How to Focus Stack: Photography
Time is also a factor. Photo stacking can take upwards of 30 mins, depending on what you are photographing.
The following is one focus stacking technique that you can follow.
Step 1. Place your camera on a tripod.
Step 2. Compose your image by framing your subject. Your subject needs to extend away from you/the camera somewhat.
Step 3. Figure out the correct exposure. Your camera needs to be on Manual mode (M).
Step 4. Your ISO should be as low as possible.
Step 5. A slow shutter speed is not a problem here (that’s why we have the tripod, among other things).
Step 6. Set the camera to Live View. This will help you focus the object easier.
Step 7. The focal point needs to be on the closest part of your subject. Use the camera zoom (+ symbol – don’t zoom with the lens) to preview the focus.
Step 8. Use the focus ring to ensure optimized sharpness. Take the shot.
Step 9. Use the live view to set the focal point slightly farther away. But don’t disturb the camera, tripod or any other settings. You will have noticed what part of the image was in focus in the first image. Use that to place the 2nd focus where the 1st focus stopped.
Step 10. Repeat steps 5 and 6 until you have the entire subject covered. Use the below images as a reference guide.
NB: Between 6 and 30 images are best for optimal focus.
How to Focus Stack: Editing
To edit your images, you will need Adobe Photoshop or another dedicated program for focus stacking. Here, we will show you how to do this through post-processing in Photoshop.
NB: It is always better to have the most updated version of Photoshop, but any version from Photoshop CS6 will allow you to do this.
Open Photoshop. Go to File>Scripts>Load Files into Stack. This will place all of your images into layers.
A Load Layers panel will open. Use browse to locate your files.
With your files added, make sure Attempt to Automatically Align Source Images is checked. This will auto-align the images for you.
In the Layers Panel, you will see all the images as layers.
We need to select all stacked images. Click on the first image.
Hold shift and click on the last image. This will select all images.
Go to Edit>Auto-Blend Layers.
The Auto-Blend Layers panel needs you to make a decision between Panorama and Stack Images. Make sure Seamless Tones and Colours is checked.
Content Aware Fill Transparent Areas will fill any areas of the images that lack information. You can bypass this, and crop the image later.
The image will load. Be patient.
Here you have your stacked image. The subject will be entirely in focus (that is if you focused properly during the photography stage).
Select all images in the Layers Panel.
Right-click for options. Go to Flatten Image.
Here is my final image after some cropping and increased brightness.
We have a great article on focus stacking for still life photography you can check here.