Stacking images in DSS

[oldfruit]

Having recently got some lights of m51 and stacked them in DSS i was wondering?

 

If i wanted to add more subs later do i have to restack the original subs with the newer subs?

Or is it possible to stack the autosave with the newer subs as this option would be slightly easier and less time consuming?

 

Replies gratefully received.

 

Thanks for looking.

 

Mark.

[+Graham]

Having recently got some lights of m51 and stacked them in DSS i was wondering?

 

If i wanted to add more subs later do i have to restack the original subs with the newer subs?

Or is it possible to stack the autosave with the newer subs as this option would be slightly easier and less time consuming?

 

Replies gratefully received.

 

Thanks for looking.

 

Mark.

 

 

That is a really good question Mark.

I have always restacked when adding more data.

I cannot see how you could use the autosave as it has been calibrated by the stacking process.

If you add more data the calibration parameters will have changed.

[oldfruit]

Thanks Graham, that option seemed too good to be true.

[dawson]

Could you run both options and show us the results?

James

[Perkil8r]

Right then....... are we sitting comfortably?

 

Load in your subs, flats and darks for session one as you normally would.

 

Then

 

Go to the bottom and click the tab that says: "Group 1"

 

Load in your subs, flats and darks for session 2 just the same way.

 

If you have more than two sessions then load each in this manner, at the bottom the "group" tab will increase with each that you add so just repeat the process.

 

Once all of your sessions are loaded, stack as per your usual actions, DSS will (I think) register the whole lot, stack sessions together then stack the final median images from each using the registrations from those to give a single image just like normal.

 

This method can also be used for different sub lengths, just select one exposure length as each group.

 

You can just stack them all in one group but the group method is better and does give better results, particularly if the images are a few degrees of rotation out from each session.

[oldfruit]

Thanks Mike, that is good to know. I only asked the question in the first place to see if there was an easier way around this but it appears there is not. It is good to know about group stacking though and i shall try that approach next time i manage to get some data to add to what i have already. Early days for me imaging wise so good to know these little tricks and tips.

 

Thanks.

[Perkil8r]

One thing that will help speed the process up though is to untick the box that says to register images that have already been registered.

[+Graham]

carrying on from what Mike has said though Mark.

The different groups are the sets of lights,darks and flats not the auto save.

If you do each session as it comes you can check all the lights as per normal deleting the bad ones.

When you are happy with them and before you stack you can save this final set as is. Look on the menu on the left side there is a save button above the register all button. Give the file a name ie M 51 one.

Do this for every session so you end up with a set of named files.

Then when you want to add data you can just open the saved file and you wont have to sort through the lights again.

M 51 1 goes into group 1

M51 2 into group 2 ect ect.

This will mean the only set of lights you need to check will be the new set you have just taken.

[Perkil8r]

Good point Graham, although generally I tend to delete all the rejected subs on the first time of checking / stacking them so I don't have to save the list as all the remaining ones are the ones I will stack. (also saves room on the hard drive)

Edited April 9, 2013 by Perkil8r

[+Graham]

Good point Graham, although generally I tend to delete all the rejected subs on the first time of checking / stacking them so I don't have to save the list as all the remaining ones are the ones I will stack. (also saves room on the hard drive)

 

Do you know what Mike I had never thought of that :facepalm:

I am normally so impatient I just uncheck the box and move on to the next one. :lol:

[glider]

I often use the same darks, bias or flat subs between nights.

 

If you do this then don't be worried when the subs don't actually appear in the tab for subsequent nights. DSS realises they are already loaded and uses them again from the first location.

 

After the first stack though the individual darks, bias or flat subs will be combined in a master darks, bias or flat file. In that case if I'm trying different stacking techniques I'll remove the individual subs and just load the masters. That speeds things up.