One of the most intriguing tools in Photoshop is layer alignment and blending. One practical use for these is macro photography – I have been experimenting with creating images that have depth of field that is nearly impossible to get in a single frame. (this post was originally written in Jan 09; updated Dec 09)
Here’s how it’s done:
Use your camera of choice, preferably with a macro lens. Create the normal setup with the camera on a tripod. Set up or manage lighting, put the camera on aperture priority, and meter. I typically use mirror-up mode as well, and shoot with a remote. Shoot in RAW format if you can. (I used a Nikon D3 digital camera, and the new Nikkor 105mm Macro VR lens).
Typical aperture on these shots ranges from f/8 to f/16 in the 35mm class – higher f/stops tend to soften the image through diffusion error. Start at f/8 or f/11.
I usually work close to the lens’s minimum focusing distance. I shoot several frames of the subject, changing the focal point to different parts of the subject, left to right and/or top to bottom. The camera must be absolutely still so that the frames will register with one another. If we could mark the focal points, they might look something like this:
Transfer the images to a folder on your computer. Open the folder with Bridge. Select the images you’ve captured (in this case four), press Command-R to open them in Adobe Camera RAW. You’ll see this screen:
Make your adjustments to the first picture only. Be conservative. Now click “select all” in the upper left corner of the dialogue, and then click “synchronize”. All of the RAW files will be updated.
Now click “Done” (blue arrow) in the lower right hand corner. Camera RAW will close and return to Adobe Bridge.
The four images will still be highlighted in Bridge. Go up to the main menu, choose Tools>Photoshop>Load Files Into Photoshop Layers.
The images will be loaded into a single Photoshop image with, of course, four layers. Open the layers dialogue and select all the layers.
Once this is completed (may take a while) go to the main menu, and click Edit>Auto-Align Layers. You’ll see a bigger dialogue, again just click Auto.
Once this is finished, go back to the Edit menu, click Edit>Auto-Blend Layers. Click on Stack Images, and Seamless Tones and Colors. Click OK.
Photoshop will launch into an analysis of all the layers, create layer masks to use the best portions of each layer, and blend the images. You should see an amazingly sharp image with significant depth of field. This is truly something new under the sun! Here’s an example:
My good friend photographer Ted Dayton told me about this, and I should add one of his points here: “take more pictures, with more focal points, than you think you need.” He’s right – once the images are blended, you’ll see the difference.