1. Telescopes are Optional
It really doesn’t matter what lenses you have, you can apply them to astrophotography. Short focal length lenses are actually the easiest to start out with. The short focal length allows you to do exposures of several seconds from a fixed tripod without noticeable star trails, so there’s no need for a tracking mount. This is ideal for capturing whole constellations, or for basic landscape astrophotography to add a down-to-earth context.
While you really don’t need a telescope to get started into astrophotography, you can do amazing stuff when you have one. When connected to a camera, a telescope is nothing more than a giant telephoto lens. I have two lenses for my Canon T3i camera, an 18-55mm and a 55-250mm. I also have a Celestron C6 SCT telescope, which for all intents and purposes is a 1500mm lens!
Something to keep in mind is, just like regular photography, you don’t always want a huge telephoto lens in astrophotography. In fact, there are many cases where you really want a short focal length camera lens. My telescope doesn’t help if I want to photograph a constellation or an Aurora – the field of view through the scope is far too small. Instead, a short focal length lens is exactly what’s needed.
2. The Moon is an Easy First Target
You don’t even need a tracking mount, in fact, having one doesn’t really make a difference here unless you are shooting through a long focal length telescope. The moon is so bright that you want a really short exposure. This picture below for instance is a 1/200th exposure at ISO 1600. You can easily lower the ISO to 100 and take a slightly longer exposure for a similar (perhaps even better) result.
The image above was shot through my C6 telescope, but you will get surprisingly good results from just about any lens. In fact, you can even capture nice moon photos with a compact camera. The moon is also the one stellar object you can photograph during the day, and relatively easily compose into landscape shots. Here’s an example I shot years ago with a simple point and shoot camera while on a hike, and another shot with that same camera during a lunar eclipse.
3. Capture a Constellation
Constellations are also easy targets for wide angle lenses. The difference now is we want to take longer exposures to collect as much starlight as we can without getting star trails. Remember that the sky is moving. Actually, you’re moving with the earth’s rotation. If you take a 30 second exposure just pointing up at the night sky, you’ll see the stars become streaks. You’ve probably seen photos like this, which is yet another style of astrophotography. For the purpose of capturing a constellation, we want to avoid this effect. The easy way to do that is to keep the length of your exposure in seconds multiplied by the focal length of your lens below 400. For example, with a 50mm lens, you could leave the shutter open for up to about 8 seconds before the stars start looking more like streaks than dots.
50mm x 8 sec = 400
Edit: I found a few holes in the clouds tonight, so here is a sample shot of the constellation Cassiopeia.
Cassiopeia looks like a ‘w’ rotated 90 degrees clockwise centered between the trees. The photo is a 10 second exposure with a 24mm focal length. Using the rule of 400, this one is only up to 240. If the wind and clouds hadn’t been moving so fast, I might have tried some longer exposures. The tree branches are blurry due to the wind.
4. Even Jupiter is Within Reach
When I first unpacked my DSLR and the included 55-250mm lens, one of the first photos I took was of Jupiter. Now, with a 250mm focal length, you don’t see detailed cloud bands, but you do see the Jovian moons! This picture is overly bright because, hey, I didn’t have any clue what I was doing yet! Just being able to distinguish the moons seemed like quite an accomplishment. (Click the image for a larger view.)
Jupiter has been very prominent in the sky for some time now. Whenever the clouds clear off enough to setup the telescope, Jupiter is almost always my first target. For those of you that do have a telescope and are ready to connect up your camera, you’ll just need a T-Adapter and a T-Ring specific to your camera. There are several different types of T-Adapters available, including one that slides into a standard 1 1/4″ visual back, like this Celestron T-Adapter. This is handy because you can also use a barlow or a filter. There are also T-Adapters specifically for screwing into the back of an SCT, or for 2″ focusers. Between the T-Adapter and T-Ring, you’re only looking at about a $50 investment to turn your telescope into your largest telephoto lens.
The above photo is an example of what I can achieve with my telescope and a 2.5x barlow in average seeing conditions inside the city. I want to emphasis this is a single short exposure photo – I’m not doing any special processing. Planetary photography is a case where a tracking mount is very helpful, but really any tracking mount will suffice. We are just taking short exposures, so tracking accuracy isn’t critical, and you can easily manage by just moving your scope manually.
5. No Special Processing Required
If you’ve heard much about astrophotography, you’ve probably heard terms like subframes, image stacking, dark frames, flat frames, light frames, etc. Frankly, you don’t need to worry about any of it to get pretty compelling results. The only processing I did to any of the images in this article would be a few brightness/contrast and color adjustments. Nothing you wouldn’t do to any other photograph in iPhoto, Picasa, or any other basic editor. And that was optional; I felt they were all pretty impressive straight off the camera. In short, don’t be intimidated thinking you need to do a lot of post-processing.
6. 2013 Is the Year of the Comets
We have two major comets on the way this year. Comet Pan-STARRS coming by in March, and comet ISON in November. Comet Pan-STARRS should be easily visible to the naked eye, and present a great photo op for amateurs and professionals alike. Hopefully this will be just a teaser before Comet ISON, which is predicted to potentially be visible in daylight! Two comets in one year is a rare opportunity. Now is the time to start learning how to use your camera to best capture these rare events!