The HDR trend has come and, for many, gone, but what came of it is the easy-to-digest concept that creating one photograph may actually require several images, then blend them together. For HDR photography it's the need of multiple exposures to compensate for what a digital sensor cannot do on it's own – properly expose both highlights and lowlights in an wide range photograph without sacrifice. With the same concept, focus stacking is also possible.
Like HDR, focus stacking comprises of two main components; series of photos of the same subject and some creative post processing. That's about where the similarity ends.
What Exactly is Focus Stacking?
Focus stacking is taking multiple photos at the same exposure but at different focal lengths and is best applied for macro photography. A longer focal length lens and a very shallow depth of field result in a pinpoint focal plane and often leave crucial elements of the image slightly soft. While very desirable, it can often result in less than stellar photographs. A great example of a macro photograph that could benefit from focus stacking is this one:
The photographer says these three water drops are on a piece of moss only about one inch in height. While the lower drop on the stem is tack sharp and the one above it also seems very sharp, it's easy to see even at web resolution that the right most droplet is soft. This is where focus stacking really shines.
What Gear Do You Need for Focus Stacking?
The gear you will need to create photos that are good for focus stacking comprise of:
- Digital camera
- Macro lens
- Cable release (optional but very helpful)
- Matte focusing screen (optional but really makes a huge difference)
We'll assume you are using a DSLR for this, it's possible with higher end point and shoots and even mirrorless digital cameras, but the DSLR is really what you want to be using. Additionally, you're going to need a high quality, stable and preferably heavy tripod. We're a huge fan of lightweight carbon tripods but there's something to be said about the weight of a heavier aluminum one will give you in terms of stability, especially when you consider you'll be manually focusing.
A focus screen is probably the least commonly modified piece of camera equipment on a camera, however it can be one of the most crucial. A proper screen, available for most camera makes, will make your job focusing far more enjoyable because you can't rely on auto focus or focal points.
How Do You Shoot Your Stack?
Set up the camera like any other macro subject, nothing here will change. What will is the number of photos you capture. You'll want to start at the far end of the subject and work near you, ending in 4-8 photos depending on the total size of the piece you're photographing. Manual exposure is also a must, so you don't have any alterations in highlights or lowlights. Remember, we're aiming for a uniform, sharp focus across a broad subject, not HDR.
How to Focus Stack in Photoshop
With your photos in computer, it's time to fire up some software, and you'll need at least Photoshop CS4, or CS5 for this. Load all of your photos into one file, keeping the layers in proper alignment in the order they were shot.
Select all the layers and go to Edit > Align Layers.
After the layers are aligned, go to Edit > Blend Layers and photoshop will begin its work.
Because of the blending that's being done, the sides of the final image are often slightly blurry, a simple crop will eliminate this.
A great example of focus stacking is this beautiful photo:
But you say, I really like the shallow depth of field looks and so do we! You have full control over what exactly you focus on!
This amazing photo stacked macro image comprises three photos that show the entire head in wonderful focus, while the antenna and body remain out of focus with a wonderful bokeh. Had the photographer only taken one shot, the sharpness would not be in both the head and the open mouth.