Dithering, Pausing, w Live Stacking & Sequence Control

[rockenrock]

Hi Robin,
I am considering switching to SharpCap Pro after watching your presentation Deep Sky Astro with CMOS cameras. Great video!
I realize now that my subs have been way too long for my Bortle 8 skies, and CMOS camera. I want to shorten the subs, but not increase my storage requirement, and processing time. I like PHD2 for guiding/dithering. I have read portions of the SharpCap User Manual for Dithering and Sequence Control but not quite understanding... So,
Can I set up SharpCap 4.0 to LiveStack 20 x 30 sec subs, download the stack, guiding via PHD2, dither via PHD2 (or maybe dither in SharpCap), pause 15 sec after dither, and then automatically repeat another set of 20x30 sec subs onward with new file names (001, 002, 003, etc) for the night?

During LiveStacking I do not want to register my subs as my guiding is good. I will do calibration, registration and integration in PI.

Thanks for your advice,
Roger

[admin]

Hi Roger,

yes, you should be able to do that, with the possible exception of the file naming.

In live stacking, setup the following

* Raw Frame saving to 'Save except when paused/dithering' - this will ensure that the frames coming off the camera are saved unprocessed for you to process later in PI

* Guiding tab - turn on 'monitor guiding' and 'automatically dither'. Set the dithering frequency to every 20 frames and tick the 'reduce exposure while dithering box'. You can also turn on the option to pause stacking if guiding lost if you want.

* Personally I would leave 'Align Frames' on, since you are only going to be looking at the stack on screen - the saved raw frames for later processing are not affected by this

* Optionally - tick the 'save and reset every XX minutes' box and set XX to long enough to allow for 20 x 30s exposures and dithering time

You can get your pause after dithering by using the 'Minimum Settle Time' in the Guiding section of the main SharpCap options.

Taking that approach will capture 30s frames continuously (aside from the dithering pauses) until you tell it to stop, and avoids using the sequencer. You can also do all of the above with the sequencer if you want, but that would be a bit more complex to set up.

cheers,

Robin

[rockenrock]

Hi Robin,
Thank you for your in depth reply.
As I am new to SharpCap, I am trying understand the useage for deep sky images that need 5 to 10 hours data for a reasonable image.
Per your reply I think you mean I need to manually change the file name of each stack. So if I have 30 x 30sec subs live stacked to a file, I will then need to change the file name 20 times to get 5 hrs data. (18,000÷900). That seems tedious and requiring constant attention during imaging.
Incrementing a file name automatically using timestamp or sequential counting would be a great feature.
So how do imagers get 5 hrs data? Live stack 600 ×30 sec with dithering within the live stack?
From my viewpoint, the advantage of separate Live Stacked files is allowing the full power of PixInsight to be applied to the data.
Thanks for your advice and explanation.
Roger

[admin]

Hi Roger,

perhaps slightly crossed wires - the filenames will all come out different (for instance you can include the capture time of the frame or the sequence number of the frame in the name to ensure that - see https://docs.sharpcap.co.uk/4.0/#Filenames%20Tab), however your exact original request for each set of 20 subs to have separate names will be hard to achieve (ie group1_001, group1_002, ... group2_001, group2_002, ... etc).

cheers,

Robin

[rockenrock]

Hi Roger,

perhaps slightly crossed wires - the filenames will all come out different (for instance you can include the capture time of the frame or the sequence number of the frame in the name to ensure that - see https://docs.sharpcap.co.uk/4.0/#Filenames%20Tab), however your exact original request for each set of 20 subs to have separate names will be hard to achieve (ie group1_001, group1_002, ... group2_001, group2_002, ... etc).

cheers,

Robin

Haha, always some crossed wires in astrophotography! I really appreciate you are so patient in your replies giving me and others solid advice.

Your answer now gives me the confidence to move forward (purchase!) with SharpCap Pro for my DSO...
-- I can select the best subframe length per your great presentation video Deep Sky CMOS Imaging, and the Pro tools.
-- I can Live Stack these multiple short (12 bit) subs into a higher quality sub (higher bit depth?) and save it with different time stamps in the file names.
-- I will not be over-saturating stars like happens with 5 and 10 minute subs.
-- I can dither after each higher quality sub is saved (by counting short subs).
-- I can save disk space and PI processing time (both really get large after running PI).
-- I can process the higher quality subs with normal PI steps for calibration and NSG, and then post processing.

And I can get help/advice from this forum as I learn how to use SharpCap Pro!
Thank you!
Roger