To use IRIS you really need to understand what happens in whole process of stacking. I read some ebook about it (can't find the link) and I thought I understood it but seems I didn't. I think I finally understood it after following this guide: IRIS:tä aloittelijoille (sorry, it's in Finnish).
If I understood correctly, here's how it goes:
- Make master offset/bias, flat and dark. These are all important so don't forget to take them.
- Calibrate images ("light frames"). This roughly means subtracting processed flat and dark frames.
- Transform images into RGB
- Register, which means aligning images so that stars are exactly the same places in every photo
- Stacking itself
- Postprocessing (colour balance, colour profiles...)
Then the photos:
Andromeda Galaxy. M31, M32 and M110 of the Messier objects. I took 31 of 18 second exposures. 20 s made the stars trail a bit but on 18 it was unnoticeable. First one was to check everything is in order and then 30 more. Photos were taken on my front yard. Luckily Andromeda was in such a position that none of the streetlights was in front of the camera. I also looked at it visually and I really have to say it was the most I've seen of that galaxy. Quite beautiful gray spot on ocular.
- http://www.flickr.com/photos/96700120@N06/9949337453/ - Same than above but without Google messing it up.
- http://www.flickr.com/photos/96700120@N06/9949231034/ - Alternate version
- http://www.flickr.com/photos/96700120@N06/9672634410/ - My previous best Andromeda. Quite a development. Gear is the same.
The Double Cluster: NGC 884 and NGC 869. While shooting Andromeda I looked through my 200 mm Dobson at everything I thought I might see. I realized I've never seen the Double cluster although it should be easy to find. It looked nice so after 31 exposures of M31 I took 30 of this. Same 18 second exposures than before.
- http://www.flickr.com/photos/96700120@N06/9949341193 - Same than above but without Google's resizing it.