Need help with DSS

[aram535]

So I took my first attempt at doing a stack, but I have failed. :-(

I setup the camera and laptop to do 30 second exposures every 35 seconds, ended up with 24 images, here is one of them. I knew there was a lot of light near my house but this was just a test before I go out and spend several hours out there. I set it up and watched tv for a while.

The problem is DSS at the moment. I added all 23 frames (DNG) Checked all, computed offset, Stack checked pictures.

Two problems:

1) The preview after it is finished shows startrails. Which was not what I wanted.
2) The (146mb) TIFF that is produced is not valid. PS CS4 or Infraview cannot open it.

Options used:
Standard Mode
Average Light
Bilinear Alignment
(I followed the recommended configuration for the Light channel)

Any ideas or pointers?

EXIF intact (blacks increased in LR)
http://www.mbcli.com/~awm/2009/sky/IMG_0284.jpg

[Deejayry]

I am assuming that you have mounted the camera on a fixed mount such as a tripod and not an equatorial tracking mount.

in situations where there is foreground objects in view, DSS can get confused, by trying to align on bright specs of foreground detail. it is worth performing the registration of images first so that DSS selects the objects it determines as stars, then browse through the images and look to see what DSS has selected as a possible star, make sure that you manually deselect any foreground objects from the images. once this is done you can perform the stacking procedure.

another thing to look out for is the actual number of stars that DSS detects, this can be adjusted by changing the star detection threshold. i usualy find that best results are achieved when the number of detected stars are between 50-100. adjusting this can sometimes prevent DSS from picking up objects that are not actually stars, such as foreground objects mentioned before and also hot pixels, although i would imagine that there arent that many on your 1d

DSS provides options to save in several different tiff formats, some of which arent recognised by PS. IIRC the 16bit -int format will work, but i'm not at a computer with DSS right now so i cannot confirm. Later versions also allow to save the file in FITS format, which i prefer to use over tiff. in order to open fits files in PS you will need FITS Liberator which you can find here, sometimes fits liberator can be tricky to install as sometimes the files get put in to the wrong plugin folder for PS. if you have any issues i'll help as much as i can.

[aram535]

Yes it was mounted on a fixed tripod.

I see, I'm sure the lights coming through the trees can confuse DSS, I did not think of that. I didn't pay too much attention to the scene as this was just a test, but I should have been more selective.

I'll try the recommended options.

Thank you very much for helping. I've been holding out for no moon and no clouds but I'm not having much luck at the moment.

[DSLR AstroMod]

Looks fine to me, try using wider end of lens to reduce trailing and allowing more star light in. Set f to maximum. Check trailing after each test shot to work out your max exposure time before trailing and go with that.

oh and save final image in DSS as a 16 bit TIFF. PS will open that.

[aram535]

Wide than 14mm?
f to maximum, as in open or closed?
Good suggestion on the exposure check, I am not actually getting trailing in my photo, it was DSS that was creating the trail (AFAIK).
The shot above is a 30 second exposure. I could go to bulb and do it for longer but this seemed to be enough.

[DSLR AstroMod]

try median or sigma clip stack option in DSS - it should ensure trailing isn't produced.