Photo stacking is a great technique which is applied in post processing to multiple photos of the same object when using a macro lens, or a lens with a long focal length. The final image show here comprises of 11 photos, each with a different focus point. Using Photoshops Auto-Align and Auto-Blend features, all 11 photos were blended together to show on final image with a good range of depth of field.
When you photograph and object close up with a macro lens, you get a very narrow depth of field, even when you shoot at f8. Take a look at the photo below to see what I mean. You can see that I focused on the left hand side of the flower head, which is nicely focused, but the rest of the flower head gradually softens as the depth of field decreases.
Setting Up the Shoot
For photo stacking a tripod is a must, so once I had my subject in place, the camera was mounted onto my tripod, camera mode set to Manual (so I had control over the exposure settings), and my first focus point selected. ISO was set to 400 (used natural lighting), f8.0 which gave me a shutter speed of 1/45 sec.
To choose my focus point, I half pressed the shutter button, and used the ‘D-Pad’ on the back of the camera to set my focus area. For the photo above, I was able to keep the camera in Auto-Focus mode, but there are many times when you will have to manually focus the camera as the lens may just keep ‘hunting’ for somewhere to focus.
After I had my first photo, I changed the focus point by using the ‘D-Pad’, re-focused and took another shot. This procedure was repeated until I had focused on all 11 focus points, adjusting exposure where needed.
The next stage is to bring all the photos together to create one final image. I have used Adobe Photoshop for stacking my photos, but other packages are available. Another recommended (although I have not used it) piece of photo-stacking software is by Helicon, but there are a number of other programs available out there. my examples here I have used a Nikon D90 with a Sigma 1.8 50mm macro lens.
Stacking the Photos
Now that all the photos are on the computer, all 11 photos were selected in Lightroom. By right-clicking on one of the photo’s thumbnails, choose Open As Layers In Photoshop. This is a great option for when you are importing multiple photos into the same document. Otherwise, you would have to open each photo individually and copy and paste each photo into one document (and be time consuming).
Once all photos have been imported into Photoshop as one document, first unlock the background layer by double-clicking on it. You can leave the default name of Layer 0 as it is. Next select all of the layers in the Layers Pallet by selecting the bottom layer (layer 0) and holding down the Shift Key, click on the top layer. All layers should now be highlighted.
Even though the camera was tripod mounted, its still a good idea to get all the layers aligned. When using macro lenses even the slightest movement and create a large difference. From the Edit menu, select Auto-Align Layers. When the dialogue box appears accept the default setting of Auto.
More often than not, you will now need to crop the image slightly. After the Auto-Align has finished, select the Crop Tool by pressing the ‘C’ key, and crop your image as needed.
With all the layers in the Layers Pallet still selected, once again go to the Edit menu and this time select Auto-Blend Layers…
When the dialogue box appears, make sure you click on the Stack Images and click OK. Depending on how many photos you have, file size etc, this could take a little while to process.
After the Auto-Blend Layers process is complete, you will now see that Photoshop has created and applied a Layer Mask to each layer.
If you images have not blended correctly, you can select each layer mask and either ‘paint away’ parts of the individual layer (with black as the foreground colour), or ‘paint-back’ parts (with white as the foreground colour).
There is a great little shortcut function in Photoshop, Press and hold the Shift, Alt and CTRL and then press the E key. This will create a new layer combining all the layers below it making it far easier to work on. It also keeps your original layers in tact in case you need to go back to them.
Now you have your stacked photo image, you can continue processing your image as normal by applying Levels, Sharpening or using third-party plug-ins.
For my final image I applied Topaz Detail 2, and applied selective levels using a Levels Adjustment Layer.
A couple more examples of photo-stacked images. All taken with Nikon D90, Sigma 50mm Macro Lens and processed in Photoshop. I’ll add more shortly.
We’ll Meet Again: I liked the way I’ve managed to isolate the main headstone, but also keeping the background just out of focus on this one.
In Memory: I wanted to mainly focus on the words on the headstone for this image.
Orchid: Admittedly, I could have used a better colour background for this one, but its and example to show.
Ivy Leaves: I missed the bottom leave for focusing on this one – must check view finder more often!!