To stack a directory of images (not RAW) to make a composite equal to one long exposure. Set camera for 15 - 30s, put in burst mode, and lock cable release down to take a cardfull of images. The main advantage of this program is that only two images are open at the same time, thus will not tax the memory and hard drive.
Directions for use:
Create a blank all black image, the same size as the images you wish to stack. Leave it open. This is where we will stack all the frames. To initiate the batch stack, load action into action pallete. Then File --> Automate --> Batch. Select directory of files as source, and NONE for output directory. Hit Ok, and the images will open, stack and close in succession. When finished, the flattened image left on the desktop can be saved under any name. Note: It takes a lot of time to open large uncompressed Tif images and may take over an hour to stack hundreds of images! But the results are as seen in the above image.