Some of the most dramatic astrophotos I've ever seen have been the result of the most simplistic of setups, but require some knowledge of the celestial sphere. The milky way, we've all seen it, especially on dark moonless nights stretching from one side of the horizon to the other. It's most pronounced in the dog days of summer, with the summer constellation, cygnus the swan riding high overhead. Cygnus is also the home of another easily recognized asterism, the northern cross. The cygnus region of the milky way is one of the most easily photographed and breathtaking areas of the sky, and can be done with a simple guiding system and camera capable of 5 minute exposures. Before we go any further, he's a sampling of a photograph of cygnus taken from a dark sky with a good guidance system:
I took this photo about 4 years ago, really before I had any idea what I was doing, and was shocked to see it come out. The idea is really simple, you have to have a telescope mount, and you need to have that mount polar aligned, this means having the optical axis of the scope pointed to the north celestial pole (which is very near polaris). This is somewhat difficult to grasp, but if you can do this, then the rest is a breeze, literally. Others have pontificated on this at length, so I will you point you to this web page, DarkskyImages.com. I have referenced them repeatedly. In general, the better your polar alignment, the long exposures you can take. A lousy polar alignment, you can shoot for a minute or two, a good one, you can go 15+ minutes with a camera with a 50mm lens. So how do I couple the camera to the telescope or the mount? Take a look at this picture:
Your eyes do not deceive you, this is whats called "piggyback photography", where the camera is mounted to the telescope (or directly to the mount), in this image, I mounted it to the telescope with a homemade wooden bracket and bungee cords (hey, any port in a storm). With this setup I was able to shoot 5 minute exposures, you can do the same. So to recap, polar align your mount (it must have a RA drive, right ascension), mount the camera to the scope or directly to the mount, point the camera at the milky way, and shoot. To give you an idea of what's possible after some experience, here is a digital stack (more about that in another post) of three 15 minute exposures of the southern part of our milky way. If your ever standing at the north end of a lake in the summer time with a clear dark sky to the south, be prepared to have your breath taken away, it's one of the most amazing sights to behold, I saw it when I was 9 and will never forget it, the center of our galaxy stretching down to the horizon. Enough of my walk down memory lane, here's the photo:
In these milky way photos, you'll see blotches of red, that's hydrogen alpha emission nebula, or more commonly known as, nebula. Don't bother looking for them with your eyes, you won't see them as anything more than a hazy smoky blotch, why is this? Two reasons, your eyes take snapshots of the world around you, long exposure photography collects multiple snapshots so it shows more. Secondly, your eyes ability to pickup light falls off dramatically as the light waves approach infrared. Hydrogen alpha emission nebula are at 656.3nm, very close to IR light, so only films and DSLRs that are sensitive to this light can record it. The best film still in print for this purpose is E200 slide film, although there are some others. Even if you don't care about recording hydrogen alpha, other films can record the starlight, which is a worthy photo in and of itself.
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