After about 15 years' absence from amateur astronomy, I re-entered the hobby mid-summer last fall. My interest has always been in astrophotography, so it wasn't too long before I started attaching a camera to a telescope. Well, as with any new skill, there was a learning curve. So, while I did get some results they were a little on the rough side.

The first two images that I was happy with are shown here at the left (click for larger image). Messier 31 on the left, Messier 33 on the right. They were both taken using my Orion Short Tube 80 refractor. A 400mm achromat that I bought as part of an autoguider package. It provided a nice wide field for these larger targets, with a Canon XSi for the image acquisition mounted on a Celestron CG-5 ASGT mount. I'm still very bad about recording image information, but I believe these were done by stacking ten 2-minute exposures in Deep Sky Stacker. These images were taken before I knew anything about focusing masks, so the focus on M-33 is a little soft. Plus, the chromatic aberration of the achromatic lens can also be seen as casting a slightly purplish color to the stars. I guess they're not bad for first attempts.

Now, almost exactly a year later, I've upgraded some equipment and learned even more from trial and error. Below are the same two targets taken the night of 9/3/2010:

Although these were taken with the exact same size telescope, there a a few key differences. The telescope is an apochromatic triplet, a TMB80SS. Triplets have better color correction so they don't show the purple fringe that an achromat does.

Instead of my XSi, these images were captured with an SBIG ST8300M CCD camera. This is a purpose-built cooled monochrome camera. For color, images have to be shot thorough red, blue and green filters then combined with software. This tri-color technique has been around since before color film existed and was used to produce the very first color photographs. However, instead of stacking three film negatives by hand, the three mono images are stacked and processed using software. In addition to the RGB images, a Luminence layer is added to provide more depth and detail to the image. In actuality, the luminance layer accounts for the majority of the data used to make up the final image.

This is where the biggest difference between the two sets of images comes into play: integration time. Both of the 2010 images have 60 minutes of luminance (20 X 3 min), and 60 minutes combined RGB (10 X 2 min per channel). Although, I had a focuser mishap on the M-33 sequence, so the blue channel only has four 2-minute images. All images were taken at a temperature of -5C and calibrated with 150 dark frames.

I still have a ways to go, but I think there have been some definite improvements over the intervening year. I would like to be able to bring out more color in these two galaxies. And that's where I'm still a bit on the weak side: post processing. I've seen many fine images of these and due to their close proximity to us they show more color than most galaxies, especially in the red where many star-forming hydrogen alpha regions are prevalent.

Indeed, the image seen at left shows some of those hydrogen alpha regions. The biggest difference with this image is that I actually took an image using an h-Alpha filter and substituted that image for the red channel. But, it was taken through a different telescope, so the image scale is different, so combining it with the image above would take more image processing skills than I currently have. If I get another clear night before it gets too cold for me, I'll get some h-Alpha data that I can mix in with the TMB80 data.

At this point, I think I'm happy with the equipment choices that I've made. Now, it's just a matter of getting out under the stars, gathering data and gaining more knowledge and experience with image processing techniques.

Easy.

Right?