Matt Molloy. Usually picture putting is used either to make HDR pictures or to improve level of area of the photographic camera or a time-lapse video clip. Mr Molloy used the same strategy, at the same time in a different way, to generate extra common pictures of the sky that looks like smudges or sweep swings.
Matt Molloy, describes his methods to PetaPixel:
To make these ‘photo stacks’, I first shoot a timelapse, taking a photo every 5 seconds or so. (Settings differ depending on the subject and lighting conditions). I then merge several photos into one image using Photoshop. I start with the first image from the timelapse as a normal photo and then blend the rest of them with the ‘lighten’ blending mode. This only adds things that are brighter than what was in the first photo, and so you can see things like the paths of stars as they move across the sky. (The movement of the stars is actually from the earth’s rotation).
I think it’s an interesting way to observe time. You can see a time frame of several hours in one image, something our eyes can’t do naturally.