When a lens magnifies an image so that it becomes larger than life-size (i.e. macro photography), the depth of field decreases. It’s just physics and there ain’t nothing you can do about it. Well, you can stop down the lens (use a smaller aperture = larger f number), which increases the depth of field a bit, but very small lens apertures introduce aberrations into the image as well as reducing the amount of light reaching the sensor/film, so they only help a bit. This is where focus stacking comes in. With a set of low depth of field images representing optical slices through an object, computer software can be used to magically blend them together to form a single sharp image. You can buy special software to do this, but I do all my stacking in Photoshop. You can see the results here. But if you want to see the masters of this craft, look at the wonderful work of experts like Thomas Shanahan and Eddie the Bugman.
Focus Stacking (Photoshop CS5):
- Adjust photos in RAW.
- Open files in Photoshop. The easiest way to do this is:
File > Scripts > Load Files Into Stack > Automatically Align Source Images.
(Alternatively, you can do this one at a time if you insist: Select whole area of all images; File: New; Paste each jpeg into a new layer. In Layer Palette, select all layers. Edit menu > Auto-align layers.)
- Edit menu > Auto-blend layers > Stack Images, check: Seamless Tones and Colors.
- Final Adjustments, crop edges.