[masraum]

Not my best work, but the Andromeda Galaxy, Messier object #31, with two other galaxies, Messier objects 32 and 110.

This was taken with a Canon Rebel XT with a Sigma 70-300 APO DG Macro zoom lens on a tripod. I took fifteen 1.3 second exposures and stacked them together. By stacking them the signal to noise ratio is increased which gives a better photo. It also allows for an exposure that's effectively longer without the heat/noise increase that's natural when a digital camera takes a long exposure photo. Also, without a tracking equatorial mount for the camera, a long exposure results in a blurred/streaked image because the earth is rotating. Rotation in a photo can be noticeable in shots well under a second. If you shoot at wide angles <50mm you can get away with shots 15-20 seconds long, maybe even as long as 30 seconds. At 300mm, the motion is pretty noticeable at 1.6seconds. Even in this photo, you can tell that my stars look like dashes instead of pinpoints as in the photo below.


THe fuzzy elongated spot to the above right of the main galaxy is M110, and the round, fuzzy, brighter dot on the lower left edge is M32.

And for comparison's sake, here's the same thing, but taken with a telescope on a tracking mount that was able to take a long exposure.

I DIDN'T TAKE THIS ONE.