What is Focus Stacking?
Focus stacking is essentially capturing a series of multiple images with the camera and focussing on areas of the subject from the closest to the furtherest distance of the subject and getting multiple image in between. Then all the images are combined into a single final image.
To obtain the image of the St Andrews Cross Spider below I wanted to get all the spider and also the spiders web in focus, to enable me to capture the spider in its environment with all in focus.
I used the set up below with the camera and lens mounted on a focussing rail. The focussing rail is as described in this Blog, however any accurate focussing rail can be used as long as it keeps the camera/lens combination stable. The focussing rail in turn is mounted on a stable tripod and a remote shutter release is used to keep the equipment stable.
The spider image above was captured at f/11, 1/80 second and ISO 1,o00. Set the camera to manual focus and also to manual exposure after metering the subject lighting.
Start by focussing the camera on the closest part of the subject to the camera, then slowly advance the camera using the focussing rail closer to the subject in increments of around 1mm. In my case above I obtained 12 images before the camera was focussed on the part of the subject furtherest away from the camera. As you advance the camera, do not alter the focussing of the lens.
Once you have all the images available then they can be processed in Photoshop.
To load the images select, File / Automate / Photomerge, select Layout Auto but do not check any other options.
Browse for the Source files and select OK.
All of the images will then be layered in Photoshop, select all the layers from the layer Pallette.
Select Edit / Auto Blend Layers.
Then select Stack Images and select Seamless Tones and Colours.
Select OK and all layers will then be blended together.
Finally all layers can be flattened. Select Layer/Flatten Image.
The completed image can then be cropped and post processed to your liking.
End of Tutorial.
Incidently the Nikon 200mm lens is an ideal lens for stacking images of small subjects. There is a review of the Nikon 200mm lens here.