Galleries 2
Collections 0
Groups 0
Created 9-Sep-12
Modified 9-Sep-12
The two albums here are the photos from an experiment in focus stacking. The technique is to take multiple photos of the (small) subject at a range of subject distances (using focusing rack mounted on a tripod). Because the the subject distance is so small (using a macro lens) the depth of field of each shot is very narrow, so the idea is to make the whole of the subject appear in focus in at least one of the shots.

Once the shots are taken, they're combined using special software (I used an open source program called CombineZP) to produce a composite in which the whole subject is in focus.

I used Photoshop CS 5.1 to perform the intermediate step of automatically aligning the photos and then cropping the images to cover just the subject. CombineZP is supposed to have a similar function but it always crashes for me.

The first photo in the album shows just one of the (25 total) shots, focused close to the nearest part of the subject.

The second photo shows the combined image, using a technique called pyramid stacking (CombineZP has a lot of different methods it can use, but this one worked best for me). You can see it's sharp pretty much everywhere. The exception is around the edges, where the background isn't in focus. I assume this artifact is because CombineZP has chose the wrong image to use for that area. It could be corrected pretty easily is Photoshop using layers.

The third photo shows the shot focused close to the front of the subject, but using f/32 instead the f/10 I used for the stacked shots. You can see it gives a greater DoF, but overall sharpness really suffers.

The only difference between the two albums is that the images in the second one have been somewhat corrected for the tungsten light I was using. (The earrings are actually silver!)