There will be times when you will need to get something entirely in focus. Focus stacking is a powerful technique for achieving super-sharp details throughout the image.
This article will show you how to use focus stacking for sharp images.
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What Does Focus Stacking Mean?
When we use a wide aperture (such as f/2.8) and a short subject distance, the depth of field is at its minimum, covering a tiny part of your subject. This is great for singling out and forcing attention on a small area, but sometimes we don’t want that.
Focus stacking involves ‘stacking’ together images to achieve a larger depth of field. The images will have different focus placements.
This technique is primarily used in two fields of photography: landscape and close-up. Of course, it’s not limited to these.
Choose the Ideal Aperture for Focus Stacking
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 focal length.
Why Not Use a Narrower Aperture?
Why can’t you simply use a smaller aperture (f/16), you might ask? Well, a smaller aperture would, indeed, place much more of the subject in focus.
But it might also place sharpen up 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.
At high magnifications, even the narrowest aperture is not enough to get everything in sharp focus.
Diffraction might also be of concern. If you’re going for ultimate detail, you’re limited to apertures below ~ f/11.
Also, consider the light conditions and relative distance to your subject. You might need a wider aperture to freeze motion (like flowers in the wind in a landscape situation).
A wider aperture lets in more light. This keeps your ISO down and your resolution and image quality at their highest.
How to Focus Stack: Photographing the Subject
Time is also a factor. Photo stacking can take upwards of 30 mins, depending on what you are photographing.
So how do you take focus stacking photos? 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. 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.
Here are the images I’ll be working with. The orange circle indicates their current focal plane.
How to Focus Stack in Photoshop
To edit your images, you will need Adobe Photoshop or a dedicated program for focus stacking. Here, we will show you how to do it 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. 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. After clicking OK, Photoshop will place all of your images into layers.
In the Layers Panel, you will see all the images as layers.
We need to select all stacked images. Select the first image, hold down Shift and click on the last picture. This action will select all the photos.
Go to Edit>Auto-Blend Layers. You need to decide between Panorama and Stack Images. Make sure to select Seamless Tones and Colours.
Content-Aware Fill Transparent Areas will fill parts of the images that lack information. You can bypass this, and crop the image later.
The image will load. Photoshop will find the sharpest parts on each photo and mask them. 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. As you can see, every part of the toy car is in perfect focus.
We also have a great article on focus stacking for still life photography you can check here.