This tutorial will teach you how to layer your pictures to form star trails in Photoshop. Click on the pictures to see a larger version of them. But before you continue reading please read this first.
Step One: Open up the first six or so pictures of your sequence in photoshop. Make sure these pictures were taken with a tripod, and that there are no noticeable shifts in any of the pictures.
Step Two: Once the pictures open up. Click on the second picture of the sequence and then click (command+A) or (ctrl+A) if you are on windows. This will select everything in the picture. Look at the picture below for an example. Image 373 is the second picture in the sequence. Image 372 is the first image in the sequence.
Step Three: Copy the picture (command+C) or once again (ctrl+C) if you are on windows. Then paste it on the first picture of the entire sequence, which for us was Image 372. To recap we copied Image 373 onto 372. Once you do that, it should create a layer called “Layer 1” (as shown below.)
Step Five: After changing the layer from normal to lighten. Merge this new layer to the first picture of the sequence by clicking (command+E) or (ctrl+E). After doing this, move on to the next picture in your sequence. Add that to the picture with the two layers, giving it three. Then the next picture will add a fourth. Don’t forget to keep merging them as you go. After merging the layers it should just say Background again. In another recap essentially what we did was, add Image 373 to 372, changed the layer from normal to lighten, and then merged that layer with the background. The next picture in the sequence would be 374. That would be added to 372 and the same thing would be done. Then you would add 375 to 372 and so forth. Understand that your sequence will most likely use different numbers.
Repeat these steps to add on all of the pictures of your sequence, after you add on all of the pictures you have opened up, close all but the original picture (the one you are adding the layers to) and open up some more of the sequence. Continue copying the pictures and pasting them onto the layered picture, making sure you change the layer type to lighten. Don’t forget to merge the pictures as you go, otherwise photoshop might start slowing up because you are using too much of your computer’s RAM. It is a long and tiresome process, but it will give you great results.
If you have any questions or need any help please leave a comment and we will address it.