How can I sift out my poorer images?

[swag72]

I have been out tonight and taken shed loads of subs, I hope for M31. As this is only image number 3, I am still at the totally bemused and befuddled stage!! So a quick question for you.

When I load the subs into DSS is there a way to tell whether some subs are better than others? I don't want to have to try to wade through 1.5 hours of subs to try to decide what to use. I noticed last time I used DSS that there was a score on the right hand side - Can this be used to weed out the rubbish?

[swag72]

Anybody? How do you determine what are poorer images?

[Psychobilly]

Score is a good way to start...

You can also sort the order that image files are listed by clicking on the labels at the top of each column.

ones to have a look at are

FWHM - smaller is better

Skybackground if the exposures have all been the same duration and iso then higher background values could mean passing clouds etc...

You can adjust the level at which DSS rejects frames when your stacking...

I used to stack everything and if there were issues in the final image go back and look for the dodgy ones...

Billy...

Just found what appears to be a bug in DSS with multi-monitor setups ...

[RobH]

I go through all my subs manually, and I sometimes have over 24 hours worth.

Sometimes, if you want a really good result, you have to do a bit of work!

[swag72]

Can I just ask - the DSS score - the higher the better right? Also, how does DSS score the subs?

[Psychobilly]

Straight from the help files....

What is the score, and what is its meaning?

The score is a measure of the picture quality.

To put it simply, the higher the score, the more round and not too big stars were found.

Is the score a measure of the absolute quality of a picture?

No. The score is a relative measure that is only used to sort the pictures of roughly the same area in order to keep only the best pictures for stacking.

If the raw development process settings are modified you must register the pictures again and a new score will be computed.

[Catanonia]

I definately recommend doing it the old fashioned way and by human eye.

Can be a pain, but worth it.

Load them into DSS and cursor down them in the list, it will show them on screen and you can decide to keep or reject.

Then with your new list, set DSS to use 100% of the images.

[carastro]

I never used to check mine, but have learnt that examining each sub is a wise thing to do.

i.e. plane flew through one sub.

i.e. focus slipped after a number of subs, so if I had stacked them all, the whole lot would have suffered from poor focus.

1.5 hours worth is not a lot to check, unless you're doing short subs.

You can set DSS to stack the best percentage if you really don't want to to check.

Carole