Stacking the moon

[qnr]

In alfredo's "I'm starting to figure out how to photograph the moon." thread, I was talking with him about how to stack photos. I decided to take some shots tonight and stack them, to give an idea of the results for those that have never tried to use stacking before.

Moon straight out of the camera
This is (one of) the original shots. Taken using the 400mm prime (800mm film equiv). Not too bad by itself, but stacking can improve it. I deliberately shot it at a higher ISO to show how the noise can be cleaned up.
Details: Aperture Priority, 1/800 second, F/11, ISO 1600

Moon-stacked with "normal mode"
This is an example of a number of individual frames stacked in the gimp using "normal" mode. What this does is increase resolution and reduce noise. Resolution is increased because fluctuations in the atmosphere show and hide details in the individual photos. In a similar manner, noise is reduced, because the noise is random, and doesn't get "reinforced" from image to image.

Moon-stacked with two modes simultaneously
This photo uses the exact same photos in the stack that were used in the previous photo. However, in this case, I'm using a combination of "multiply" mode and "addition" mode (Edit: Note that I mean on individual layers, each layer can only be one mode). Multiply increases contrast. Addition lightens the image without increasing noise. Normally, you'd use one or the other, but since I was using the same number of photos/layers for both images, if I'd stuck to just multiply, the image would have gotten too dark.

[qnr]

1. Can't edit the post anymore - so here's a screenshot of the gimp layers & opacity levels used

Edit: Note that the 14 layers is just a random thing, a group I decided to grab. I just used sequential (continuous) mode and blasted a pile of shots at once. You can technically stack with even 2 photos (and even copying each of those into another layer can help) -- however, the more photos you use (especially for addition mode, trying to bring up dim stars, for example) the better the quality will be.

[WannaJumpMyScooter]

2. very slick

bz

[qnr]

3. Thanks - it's interesting what it can do. I once experimented with a totally dark

room, with the idiot light from a battery charger being the only source of light. Using additive stacking, I was able to read the titles of books on the bookshelf.

[alfredo]

4. Thanks. I've copied and saved the instructions.