Newbee questions

This is my first attempt at shooting a semi-long exposure with my Canon 20D piggybacked on a C8. Unguided and not so perfect focus. I was just experimenting with polar alignment and stacking photos in registax.

This is a 127sec exposure, ISO800, with 80mmFL.

The photo is really washed out. Is this normal? Light pollution? I have 5 exposures like this that all look the same.

I also see two dark spots which I thought was dust on the sensor but cannot be removed with a blower. Does this mean a trip back to Canon for cleaning?

Thanks in advance for any advice.

Also, I cannot seem to load my RAW dark frame into Registax. WHY?

Attached Image:

That image looks pretty normal for that length of exposure. From my area which is usually about mag 5.5 on a good night I usually don't bother with exposures over 1 min. with my 20D. Usually if I use an 80mm F6 refractor and the 20D I will start seeing sky fog after about 30 sec. at ISO 800. If I go to a darker site then the exposures can be quite a bit longer. The dust specks on the sensor can be cleaned off by using the sensor cleaning mode on the camera and special sensor swabs made for that purpose:

http://www.photosol.com/swabproduct.htm

I haven't gotten around to cleaning my 20D sensor with these but I really need to since there are quite a few dust specks visible.

I'm not up to date on Registax so hopefully someone else can answer that question.

Joplin

Red cast is light pollution and is 'normal'.
You have couple of methods dealing with it -
1. light pollution filters (Astronomik CLS and Lumicon LPS are popular, astronomik has clip version which you could use with Canon).
2. after processing.

You have to do after processing anyway with PaintShop Pro, Photoshop or some graphics program that can handle at least curves and levels.
Attached is your image with minimal tweaking with PSP and curves/levels.

Dust is common problem with astro imaging. Again there are couple methods
1. cleaning sensors and/or filters
2. taking a flat frame (just google flat frame)

Registax is not very good software for deep sky imaging.
Try DeepSkyStacker which is very easy, powerful and free.
It can handle Canon raw files and you can use flat frames (and dark frames) with it.

Attached Image:

Welcome to the world of astrophotography. You've just discovered what flat frames are for! You mention that you couldn't load your dark frame into Registax (sorry, can't help - I use MaxiM) so I assume you took one with equal length and temperature of your 127" image.

You're on the right track. Longer (or more) stacked exposures with associated dark frams will boost Signal/Noise ratio and clean up the picture. The flats may not even be necessary with a higher S/N ratio but if you use them, they will eliminate your dust bunnies.

Here's a nice "How to" guide: http://www.saratogaskies.com/articles/cookbook/index-v0p5.html but just do a search, there are a ton of books and websites dedicated to astrophotography.

Michael,

That could be dust on the sensor--but it looks out of focus enough that it could also be further out--like on a focal reducer or field flattener.

Alex