Required Items:
DSLR Camera
Tripod
Intervalometer (Available Below)
Canon
1D 5D 6D 7D Canon Rebels Nikon
Tripod
Intervalometer (Available Below)
1D 5D 6D 7D Canon Rebels Nikon
Programs
So you want to begin creating beautiful star trail compositions? Well your first step is to find a crystal clear night with no clouds and minimal light pollution. Here is a link that will take you to a map that has data on light pollution for much of the world. I recommend leaving the city if you are in one and driving to the darkest spot within reason. A program I recommend for planning your star shoots ahead of time is Stellarium, it lets you view the stars from any location and at any point in time, forward or backward. Download it for free Here. I also use Google Sky Maps to find the North Star so I know which point the stars will rotate around. Position that star in the center of your camera if you want an image like the one above.
Lenses
Generally you want a wide lens with a low F-stop, the lower the F-stop the less exposure time you need, which keeps the picture clear. I recommend the Tokina 11-16mm f/2.8 for Canon or Tokina 11-16mm f/2.8 for Nikon it is now under $500 and performs great with astrophotography and an ultra wide 11mm. Many cameras can go to up to 30 seconds on the exposure and capture a lot of light but this is can be a negative for shooting stars (look at the image below). What is happening is your camera is actually catching the movement of Earth in proportion to the stars, and the longer your exposure is open the more movement you'll get. Ten seconds and under is usually a solid amount of time but sometimes this can only be done if you have a low enough f-stop to compensate. The f/2.8 on the Tokina above works great at 8 seconds.
Camera Settings
( Exposure, ISO, Focus,White Balance)
Now camera settings will vary from make and model, lens, and the night sky but I will break down the basics. Frame up your camera looking at the North Star or subject of your choosing, open the lens to as wide it can go and bring your f-stop all the way down. I always use the LCD screen to focus the stars better, use the 10x magnification on the brightest star you can find and ALWAYS manual focus to it and leave it on manual focus for the duration of the night! Next set your camera to 5" exposure and see how it looks. If its too dark try bringing up the ISO but NEVER set it above 800ISO any higher and the pictures turn out too grainy. Try taking a couple of pictures and see how they look, if they are too dark bring up the exposure till you get a decent amount of light. Now for the white balance NEVER use auto WB! When using auto the pictures hue will sometimes vary from picture to picture and can ruin the whole thing! Just set it to any of the present modes till you get a picture where the stars show up a whitish blue, the exact preset will vary from location to location and how the sky and light pollution react where you are. I set a custom kelvin somewhere in the 3k usually, to keep the sky a cooler color.
Setting the Intervalometer
Once your camera secured to a steady tripod and all the settings are set, plug in the intervalometer. Now the camera usually takes as long as the exposure time to save the picture to the memory card after it snaps the image, so if you have a 8" exposure it will take about 16 seconds to take and save the picture. You do NOT want to set the intervalometer near or below this amount to avoid the camera skipping a picture. So set it to 25 or 30 seconds. You can program a limit on the pictures the intervalometer will take but I usually set it to -- which is infinity or till the camera dies. That way you get as many pictures as possible. Hit the start button and watch the camera for a few minutes to make sure the pictures keep taking and are turning out right. Now we wait. I always set the timer on my watch to let me know how long I keep my camera outside. Usually you want a minimum of one hour but I recommend two hours. At 30 seconds apiece there are 2 pictures every minute and 120 every hour.
Photoshopping
Import all the pictures onto your computer, hopefully you have a decent amount of RAM because once they're in Photoshop it will kill your memory. This is a good time to note that if your computer can't handle 100+ images at Large resolution try going to Medium or even Small resolution on your camera before you take the images, to save computer resources later. Now open the first image in Photoshop, then highlight all the remaining in the folder and drag them over on top of the image in Photoshop. You will have to hit Enter for every picture because it wants to you place them first. Once they are all imported highlight all the layers in the layers window and under blending options hit Lighten. This will allow the light parts of each image (the stars) to pass through all the layers and leave the darkness back. Now your pretty much done if you are happy with the way the image has turned out but if there are a lot of plane trails through the sky that you want gone, you are going to have to go through each layer and find and erase them individually, I usually use a small clone stamp tool of the night sky to quickly erase them. This can be a pain staking process that takes awhile but the end result looks a lot better.
