How to focus stack 


Images were taken with Canon 100mm macro @ f8

FS -1

Fig – 1

FS -2

Fig – 2

FS -3

Fig – 3

FS Final

Fig – 4

Focus Stacking

Primarily used in Macro Photography – Focus stacking is becoming a popular method of getting great depth of field in Landscape photography similar to traditional hyper-focal techniques. Although this method requires quite a few images and a pretty powerful computer, it is another method of creating great depth of field.

When using traditional hyper-focal methods the photographer would compose his image and then using manual focus, “fool” his camera into getting a sharp image from halfway to the first focal point in the image on to infinity. Example: You have a rock in the foreground of your composition and it is 6 feet from the nodal point of your lens. By setting your hyperfocal distance, everything from halfway (3 feet) to the rock will be in sharp focus on out to infinity.

When Focus Stacking you’re doing just that, Stacking images with different focal points in each image, typically from near to far. You may take 10 or more frames and then “stack” them in the computer using the many programs that offer such methods.

The best part is that you can set your f/stop to the best desired for a particular lens, typically f/5.6 – f/16, and avoid potential diffraction at maximum settings.

I use Photoshop CC to stack my images.

In the final image on the left – Fig 4 you can see the entire depth of field after stacking the 10 images in Photoshop CC.

Taking the images

Using a tripod set up your composition. It is very important that your composition remains consistent so the computer can make the alignment necessary during stacking.

In the example at the left, I used a 100mm Macro and a long ruler in my studio. I set the aperture at f/8 and took 10 frames. Each frame was “focused” at consecutive one-inch marks on the ruler. (1, 2, 3, etc…)

You can see on images 1 thru 3 the shallow depth of field from several individual frames prior to stacking.

Depending on your composition you may take more or fewer images. For me, more is always better, you can always toss the ones not needed.

If you are taking landscape images there are factors you need to consider

    • ALWAYS – Use a tripod to steady your camera
    • Movement – Movement within your composition will play havoc with this process. Usually, the culprit is bush/leaf movements, but any significant movement can hinder alignment. The more solid structure in the image, buildings, mountains rocks will help the computer calculate edges for alignment.
    • Use manual focus – it’s as easy as just turning your focus ring in small increments until you reached the “end” of your composition or “infinity “. On what you feel is your last shot, look through your eyepiece or at your live view to confirm focus.
  • You normally only need about 5 images in a typical landscape scene. However the farther the required depth of field (i.e., very deep/distant landscape) you might want to take more images to stack.

Steps in Photoshop

Save your images in your computer (usually in one folder) where you can easily access them.

Open Photoshop and bring all of you images into PS. Usually, these will open in Camera Raw as a set. Here you can begin to edit your images for contrast, saturation etc…even add filter effects. Be sure and select all the images and “Synchronize” them so that each image will have the same effects except of course the focus points within them. Open them in Photoshop.

cw fig1

Then go to “File”, select “Scripts” in the dropdown, then select “Load files into stacks…” click on the box “Add Open Files”. you’ll then see your images listed. Be sure to check the box “Attempt to Automatically Align Source Images”…then click “OK”

scptstk fig 2

Now you will see the images “stacked” on your layers pallet. One layer will be active. Hold down the shift key and select all the images on your stack. They should all be highlighted or active. Fig – 4 shows the stacked images all being actively selected.

layerpalstacked fig 3

Now go to “Edit” at the top of your window and in the panel that opens select “Auto-Blend Layers”. Make sure to check the boxes “Stacked Images” and “Seamless Tones & Colors”

autoblnd fig 4

After these processes, you will likely have to crop the outer edges of the final images due to alignment processes.

See Fig -4 for my final image sample. After taking images at each 1-inch increment, the result is a clear depth of focus out to 10 inches where I stopped taking images.