Astrophotography without a telescope?

[explody pup]

Today's Astronomy Photo of the Day reminded me of something I've been wondering for a while. Is it possible to capture a very dim (to the naked eye) object in the night sky such as the Andromeda Galaxy? It's certainly large enough to fill a frame even without the use of a telescope. Is the Earth's rotation too fast to get a sharp image? Would a high ISO, say 1600, help without destroying clarity? What about photographing our own galaxy?

 

[Big Mike]

I don't know much (or anything) about astrophotography...but I have read that most digital cameras have an infrared filter that makes it hard to photography the stars etc. Canon made a special release of the 20Da...which had the infrared filter removed or modified to allow for astrophotography.

 

[kwjones]

It can be done, they do it with film camera's. http://www.astrophotography.com/cameras.htm

Unless you have a tripod that has built in automatic tracking of the object you want to photograph, your best bet is to take more, shorter exposures and combining them them in a software program like Astrostack. If you has a telesope that can auto track an object, there are a few companies like www.scopetronix.com that make a device that will allow your camera to piggy back on the telescope.

 

[astrostu]

Photographing a bright object is easy. However, photographing a faint object is much more difficult because of Earth's rotation. The sky rotates 360° in 24 hrs, which boils down to 1/4° (15 arcmin) per minute. This probably doesn't mean much to you, but it's the same as saying that if you set up your camera to point directly at a star, over the course of 1 minute, that star will move 1/2 the width of the full moon. If you are trying to image something like M31 (Andromeda Galaxy), then you'll probably have a lens on with a ~6° field of view. If you're using - for example - a Canon 350D that's about 3500 px across, then the galaxy would move by approximately 150 pixels over the course of a 1-minute exposure. Andromeda is very bright, but its light is spread across an area over 40 times the size of the full moon which effectively decreases its brightness by a factor of 10,000; so a short enough shot without a tracking mount will result in black.

So, without a mount that tracks with Earth's rotation, you are limited to very bright objects (e.g., Moon, Galilean Satellite positions around Jupiter, very bright comets (rare)) or to objects where you want it to be blurred across the frame (like star trails). But if you have a mount that tracks, then you are only limited by the size of your lens (aperture and length).

Thus, to directly answer the thread's title: Yes, you can do astrophotography without a telescope. A telescope just acts to collect much more light (light collection goes as area of the lens/mirror) than a camera lens, and they usually have built-in clock drives to compensate for Earth's motion.

 

[THORHAMMER]

it would be neat to have a large telescope and tracker attached in the back your pickup, drive to a very high spot above the smog and closer to the sky. Use a laptop inside to control the shot.

better yet, the huge observatory(s) , they should let people hook up their cameras to them....rent out 20 minute periods of time or something...at night