Using DSS on subs from different nights?

[michaelmorris]

At SGL7 I was imaging with a Canon 1000D DSLR through my Orion 80ED scope. I have 45 x 300 second subs of same object taken over two nights (night 1 = 15 x 300 secs subs, night 2 = 30 x 300 secs subs). The two nights in question had signifcantly different night-time temperatures (10oC and 16oC), so I have two sets of darks and I have seperate sets of flats for each night. I plan to do the image calibration and stacking in Deepskystacker (DSS).

From what I can tell, DSS won't let me assign different darks and flats to different sets of light frames and stack it all into a single image.

So here are my questions - what is th best way to combine all this data into a single image? In principle, would there be an advantage in try to apply darks and flats to each sub then stacking them all together over running DSS twice (once for each set of data) and then simply stacking the two calibrated images together afterwards?

Thanks

[martin_h]

Open DSS and load Night 1 lights, darks and flats - if you have Bias frames load these as well.

At the bottom of that screen you will see a tab (Group 1) - click this and load your Night 2 data - lights, darks and flats

Process as usual...

See >>> http://stargazerslounge.com/imaging-image-processing-help-techniques/181581-stacking-multiple-sessions.html

[jgs001]

Be careful... if you put anything in the master group, it will be applied to all the other groups... the master group is ideal for any bias frames. Otherwise, just load a single file into the master group to open group 1, then remove it again. Then load night 1 into group 1, that will open group 2 and repeat. Don't forget to save the file list after each nights data is added

[martin_h]

My understanding was that - yes items in the master group will be applied to the other groups UNLESS you add something unique to the other group. ie. darks.

QUOTE:-

"You can create as many File Groups as you want knowing that a file may belong to only one File Group.

When you start DeepSkyStacker only the Main Group is available. As soon as you add a file to the last available group a new empty group tab is created.

Example:

You shot the same subject two nights in a row.

For each night you have a set of Light, Dark and Flat Frames but the temperature was not the same each night and the Dark Frames are not compatible and the orientation was slightly different so your Flat Frames are also different between the two nights.

To associate each Light Frame with the good Dark and Flat Frames you just need to put all the Light+Dark+Flat Frames from the first night in one File Group and all the Light+Dark+Flat Frames of the second night in another File Group.

Since Offset/Bias Frames are common to all the nights they must be put in the Main Group.

DeepSkyStacker will automatically associate the Light Frames of the first night with the Dark and Flat Frames of the first night and the Light Frames of the second night with the Dark and Flat Frames of the second night.

The Offset/Bias Frames from the Main Group will be associated with the Light Frames of the first and second night."

[jgs001]

Ok, I always took that to mean to keep the individuals in their own sub groups and keep the main/master group only for frames to be applied to all the others.

[martin_h]

You can do that, but I've always taken it to mean Master Group contains all the common files eg Bias but can also contain a set of data as well, then all other groups will use the calibration data from Main group UNLESS you add new calibration to that group, the new calibration will only be used in the group its is in, all other groups will continue to use Main Group calibration data unless told otherwise.

[michaelmorris]

Thank you so much, that's exactly the information I was looking for.