The laws of physics and current camera technology sometime make it difficult to create the image we see in our heads. Especially when shooting macro photography, your focus plane can be so razor thin that only a small part of your subject is in sharp focus. It can make for some milky smooth bokeh in your background, but sometimes you want more of you subject to be in focus to help it stand out. Through the power of Adobe Photoshop, it’s possible to combine several images of the same subject taken at different focal lengths into one image that has a greater depth of field. This technique is called focus stacking.
Taking the Images
For this technique you will want to put your camera on a tripod. Photoshop does a great job in aligning images automatically, but it does a much better job if each shot is exactly the same except for your focus point. Once you have your shot setup, start by switching your lens to manual focus and focusing on the closest part of your subject that you want to be in focus. Take a picture and then gently and carefully adjust your focus slightly further back on your subject. Repeat this process until you have a set of images that each have a slightly different part of your foreground subject in focus.
Creating the Stack
Import your images into a folder on your computer – I like to put the folder on my desktop and label it “focus stack” or something so I know what the series is and can find it easily later. If you have Adobe Bridge, you can navigate to your folder of images and open one of them in Camera Raw by right clicking on the image and selecting Open in Camera Raw. I like to make may raw adjustments to the first image in the sequence and then select Done. If you right click on this image again and select Develop Settings > Copy Settings you can copy your Raw adjustments and then use the same menu to paste the same settings on the rest of your images.
Now shift + click to select all of the images to be part of the focus stack and select Tools > Photoshop > Load Files Into Photoshop Layers. Selecting this command will open photoshop and place all the images you selected in a single photoshop document. Each image will be on it’s own layer. Select all of these layers in the layers panel and then select Edit > Auto-Align Layers. Photoshop will process for a few moments and then each of your layers will be perfectly aligned with each other.
Finally, with all of your layers selected, select Edit > Auto-Blend Layers. Photoshop will again process for a few moments and then provide you with a final focus stacked image. In this process, photoshop is clipping the in-focus parts of each image and combining those parts into an image that hopefully has greater depth of field than any one single shot. Each of these clippings will still be on their own layer. Select Layer > Merge Layers to flatten the stack of layers into one that you can continue to make other color and contrast adjustments to or save out as your final image.
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