Dithering + SCP DSO Imaging Best Practices?

Discussion of using SharpCap for Deep Sky Imaging
Post Reply
itarchitectkev
Posts: 1
Joined: Thu Sep 06, 2018 8:59 am

Dithering + SCP DSO Imaging Best Practices?

#1

Post by itarchitectkev »

Hi,
I've been using SC Pro for a while - though I know I'm only scratching the surface with basics. I'm good with getting my images captured and processed with the likes of Astro Pixel Processor. I use SC do to my Lights, Darks, Flats, DarkFlats and Bias and I think they're appropriate. I certainly get something out the end that looks like what I'm expecting. I'm not sure I'm using all the features to know how optimal this is until I spend hours after the fact/night of imaging.

I read about dithering though and for deep-sky imaging, there is a camp that says this is a must to account for any hot pixels that will always hit the same part of the sensor (and image) so you're always going to not get the detail there.
The flip-side is that new cameras and software is good for accounting for this. So I appreciate there are two camps here.

That said, I noticed that SC 3.2 now does Dithering... but its under the Live Stacking option. I don't do live stacking. Have I wrongly assumed this isn't for us lucky-imaging photographers... and if the option is only available there, how do I go about dithering? I'm using PHD2 for guiding so I have the tools.

I guess I'm also asking - what is the optimal set up with SC to do stacking of images in processing with APP/DSS/your fave in here, and can I take advantage of these features that are under a part of SC (Live Stacking) that I just don't use - and should I?
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Dithering + SCP DSO Imaging Best Practices?

#2

Post by admin »

Hi,

currently dithering via PHD is only supported using Live Stacking mode as you've noticed - this is a stepping stone to more complete dithering support in a later version. One thing you could do at the moment is use live stacking and check the 'Save Individual Frames' option which saves frames that are added to the stack (ie it will exclude the frames during dithering). You can then re-stack the raw frames in your favourite stacking program afterwards.

Documentation on this aspect of SharpCap is coming soon (I literally finished writing the first draft of the 3.2 user manual last night - it is now being proof-read and corrected). What I would say for now is that if you want to use dithering in live stacking you should make the dither interval several times longer than your frame length to avoid an unacceptably high percentage of imaging time being lost due to frames taken during dithering.

cheers,

Robin
RichardG
Posts: 3
Joined: Sat Mar 30, 2019 9:38 pm

Re: Dithering + SCP DSO Imaging Best Practices?

#3

Post by RichardG »

I am a novice at imaging, and enjoy the immediacy of Sharpcap, and have so far avoided the need to immerse myself in the world of post processing. So I was really happy to be able to get Sharpcap Pro dithering working with Phd2 autoguiding last night.

However, the end result was that each successive dither series was summated in the Live Stack image with the uncorrected dither offset, giving superimposed offset images. Should the "Align Frames" box been checked along with the "Automatic Dither" box? Or is the only way to stack the dithered images by saving each individual frame for subsequent post acquisition stacking? Is there a way to automatically save each dither "stack" when each dither move is initiated?

Thanks
Richard
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Dithering + SCP DSO Imaging Best Practices?

#4

Post by admin »

Hi Richard,

Sorry not to approve your post sooner – for some reason it managed to drop off my list of notifications.

Yes, you're right that you must enable the alignment feature if you are going to use dithering in a live stacking.

Cheers, Robin
Post Reply