ElCapichan

Today's lesson: Star Trail Photography

I was introduced to star trail photography back in November. I had seen it before but never gave it any thought and didn't even really connect what it was. I stumbled about a website that explained the process and immediately became intrigued and decided I would try it for myself while on my road trip out west. Star Trail photography can be tricky, and by that, I mean that just about no 2 websites has the same information on shutter speed, aperture, ISO, etc. To make matters even more complicated, there are different methods entirely depending on if you are using film or digital (film method can be used with digital). Not to fret, I will cover both and explain the pros and cons of each.

Gear

• Camera with the ability to use Bulb mode
• Stable tripod
• Remote release cable (100% required)
• Something to keep you entertained while you wait (Not required, but you will be glad you brought it)

Now that you have the gear you will need, it's time to do some research. Priority numero uno is to see what is going on with the moon, and there are 2 things you want to find out. First, what stage is the moon in? The closer to the new moon the better. Secondly, when is the moon going to be out? If the moon is out during the day and on the other side of the earth at night then you are good to go. Now I am not sure on this one, but even if the full moon isn't out at night, there may still be some light affecting the sky even if it is on the other side of the planet, though it may not make a lick of difference. Just aim to shoot close as possible to the new moon and try for when the moon is out during the day. Next important bit of research is the weather. If it is raining outside, you won't be seeing too many stars, plus you wouldn't want to get your camera wet. Check what the weather is going to be doing all night as you will be out there for some time. An entire photo session can be ruined if some clouds role in even if for just a few minutes.

So you have your gear and the weather is looking perfect. Now you have to figure out your composition. You could just point the camera straight up and have nothing but stars, or you could go the more original route and try to get a foreground subject in the photo.The later is a bit harder to accomplish, but it worth the effort, even if the foreground subject isn't all that exciting. If you want to go the route of adding a foreground subject, you have to figure out lighting. This is actually a case where having some moonlight can be a good thing, but don't go overboard. I'd try to steer clear of anything over a half moon, and try to be a slightly closer to a new moon. That moonlight might just be enough to light your foreground subject. If you're lucky, it is enough or at the very least give some definition to the subject. Any lights you have to offer can help. LED flashlights do a surprisingly good job at mimicking daylight, and if your subject is close enough and you are in a place you can do it, turn on your car headlights. Last, but not least, is how you want your trails to look. As you may, or may not, know, the north star is near perfectly directly over the north pole. Because of this, the star always appears to be in the exact same place at all times. So what does this mean when shooting star trails? Well the farther you get away from the north star in you image, the longer, and more circular, the trails become. Depending on the framing, the trails can either become full circles with the north star in the center or expanding arches with the north star in a corner. If you decide not to include the north star, the trails can do some cool things like trailing in different and opposite directions. Now with all that, it is time to put the camera to work and figuring out exactly what setting to use.

This is where you decide which method you want to go with. Both methods can be used on digital, but the digital method is exclusively on digital.I'll also point out the the digital method is the preferred when shooting digital, but does have a few more steps involved and could run into more problems while shooting, but I will get into that later.

Film Method

This is the simplest method to shooting star trails. All you do is turn your camera on Bulb mode, plug in your cable release and set it and forget it. Put the ISO as low as possible. This means either 100-200 and make sure not to go any higher or there will be too much noise to be able to work with the photo at all. Focusing can be a problem. The most absolute and sure fire way to get both the foreground subject and stars in focus is to determine the hyper focal distance of your lens. Very difficult to do for zoom lenses, but a piece of cake for prime lenses. Just go to http://www.dofmaster.com/ and pick one of the many methods they have there to determine the hyper focal distance for your lens. In a nutshell, the hyper focal distance allows from everything halfway between your subject to infinity to be in focus. Only problem is it's not a very easy technique to put into practice. Another method a lot of landscape photographers use is to focus at about 1/3rd into your scene. Easier to pull off, but not exact, but can prove to be much better than just focusing on your subject. With that said, focusing on your subject isn't forbidden, your star trails just won't be as sharp but you may prefer them that way. Most importantly when focusing, TURN AUTO FOCUS OFF WHEN YOU ACHIEVE YOUR FOCUS!!! Nothing more heart braking to attain that perfect focus only to see it vanish when you press the shutter button when you take the shot.

Now with focusing done with, you are going to have to experiment at this point. For your aperture, f/4 is a good place to start with, but you are going to have experiment a bit. For quicker shots and shorter trails, you can get away with f/2.8 to get more light in short time. For longer shots with long trails go no higher than f/8. The problem here is that depending on the light situation for where you are, this part is always different. The moon, light pollution, etc. can all affect what aperture you are going to need. With all that, it's time to take the picture... and wait. Put the shutter lock on the cable release and wait however long you want the shot to be. 15 minutes is a good minimum to start getting interesting trails, but you can let the camera go for hours. Just make sure to turn on your camera's noise reducing dark frame. The camera takes another shot with the shutter closed for the same length to compare images and remove noise and hot pixels. Helpful, but it doesn't get rid of everything. Just make sure your batteries can handle the time it takes to take the photo as well as the noise reducing shot. If your camera dies, the image is gone for good.

This method is good to use when you only want to deal with a single image. The downsides though are that you are going to get a lot of noise, even shooting at 100 ISO, and if you do end up losing power, you just wasted a lot of time. This method is easier and when first trying out star trails, this helps you figure things out, however I find the digital method is a much better choice and offers much higher quality photos.

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