Anyone know an easy tutorial on how to stack multiple images to get star trails?
I'm still reasonably happy with this single exposure from Alley Springs, Missouri. It wasn't a location I could have necessarily stayed at forever to get star trails anyway. I actually set up my tripod and walked back to camp for a while. The foreground was blended and aligned from the next morning.
@thomas.herbst.photography
Nikon D3200
18 mm
f/3.5
1800'
ISO 200 (this is so low because my camera is incredibly noisy in low light)
You have some very nice star trails already, but I gather that this is from a single shot and you want to create one from multiple shots for some reason (which will be more work but you can reach longer exposures, long trails).
Any tutorial would depend on what software you want to use?
And you will need an interval timer. Either built in into your camera, or an external trigger with interval timer.
I recently did it with CaptureOne & Affinity Photo. I used CaptureOne to make edits to the 1st image, and then copy those edits to the remaining images. I then exported all images as 16 bit TIFF files. (For convenience later in the process, I export them all to a new empty folder).
LightRoom, DxO PhotoLabs, Exposure X6 - they all should be able to do the same, so pick your RAW converter of choice!
I would however not rely on Affinity Photo to do the RAW conversion, and probably same for Photoshop, since then you cannot do any edits on the RAW file that would enhance them before stacking (such as, enhance micro-contrast to bring out the stars better, exposure, WB changes, etc).
Using Affinity Photo, I then create a new stack of images, add all my individual shots, and when it's loaded them all change the blend mode for the stacked image layer from "mean" to "max".
In Photoshop something similar can be done, and there are more specialized tools available to do it but you don't have to use any of them. If you already use Lightroom, then the integration it has with Photoshop may make some things easier. Search YouTube for some tutorials on how to bring your images directly from LR into PS as a stack, instead of exporting them to TIFF.
Now, quick tip, I found that it's better to have fewer images with longer exposure per image rather than a lot of images with shorter exposure per image! The simple reason is that it will take much more processing power to have like 100 images to stack, it can bring your computer to its knees easily.
So take first a short exposure shot to test your composition etc works. Then take your first long exposure shot to verify you have a workable exposure, not over-exposed nor under-exposed etc. Try low ISO and a 4 minute exposure, for instance. I hope you can do that without having to go into Bulb mode, or that you have a programmable interval timer that can set such long exposures for you?
Once you have the right exposure set up your interval timer to take a number of shots. Think about how long you want your total exposure to be, divide that by the length of each individual exposure, and that will be the number of exposures.
In your interval timer, set the interval between each shot to be as short as possible otherwise there will be gaps in the trails.
And very important for this, do not forget to turn off "Long Exposure Noise Reduction" in your camera settings!
For the rest, if you want to know more, do a quick search on YouTube! There are plenty of tutorials available, watch a few. :)