The photography term ‘depth of field’ might appear to indicate a photographic effect of depth. This isn’t what the term means, though. Depth of field, in photography, is an effect where images appear sharply in focus only in a very narrow area. It’s the kind of effect you would achieve if you focused your eyes on an object 6 feet away. Only the object you wanted to look at would be in focus – everything else, whether closer or farther away – would be blurred.
If you’ve ever admired professional photographs with artistic blurring around an area of precise focus, you can probably imagine how impressive the results would be if you had a photograph that was similarly focused throughout. This is the effect that focus stacking achieves.
The focus stacking technique works especially well with close-up product pictures. If you’ve seen a modern jewelry catalog with photographs that seem deep, yet perfectly focused throughout, you’re probably familiar with the effect that focus stacking can achieve. These photographs are created by combining several images, each one a depth of field image, narrowly focusing on a different area of the object being photographed, to create a final Image that appears perfectly focused throughout. You get effective focus stacking by paying attention to three areas:
- You need a long lens: the focal length of your lens determines the shallowness of the depth of field that you achieve (shallowness, as used here, is a good thing – it indicates how narrow an area of your image you can turn sharp while leaving the rest looking blurred).
- How close you are to the object matters; the closer you are, the shallower the depth of field that you can achieve.
- The aperture settings affect the shallowness of your depth of field, too. The longer you expose your photograph, the shallower the results.
You need a few pieces of quality equipment
You mustn’t embark on creating beautifully focus-stacked pictures without the right equipment. Depth of field can be difficult to achieve without precision and control.
A quality, macro lens should be first on your list: A long 50 mm lens like the Canon EF 50mm f/2.5 is an excellent choice for focus stacked images. Close-ups of products or of nature require that you bring your camera very close. Photographing your subject up close ensures that you get a shallow depth of field even if you shoot at f/8. If you’re shooting in inadequate light, you could mount your lens with an LED ring light flash.
You can’t do without a heavy, high quality tripod: While you can achieve focus stacked images with any tripod, you’ll have to put up with much frustration in getting your camera precisely in position and having it stay rock steady.
A precision focusing screen: Photographing for focus stacked pictures usually means getting your camera locked on a tripod at odd, inaccessible angles. You can’t comfortably look at your camera’s viewfinder when the camera isn’t at a good angle. A focusing screen can help you easily see a large version of the image in your viewfinder.
Setting up a focus stacked image can be time-consuming. You need a great deal of patience to find out how and where exactly to focus your camera for the best kind of results.
However, manual focus manipulation is not the only option available. One alternative, especially for product photography, is an all-in-one equipment and software system. Such professional equipment automates the process to create beautifully focused and professional results.
Getting the shots
The idea with a focus stacked shot is to get an image that is sharply focused throughout, even as you shoot with a high-quality long lens. You need to shoot at four different points along the subject. Once you have four shots, you can use focus stacking software (Photoshop has a well-regarded focus stacking module) or all-in-one solution to stack all your shots. The software can take the focused part of each picture and put them together to form a fully focused image. While it’s a time-consuming exercise, the results can be impressive.