SharpCap Forums

Hi

I’ve been reading a set of posts over at cloudynights ( https://www.cloudynights.com/topic/895 ... ggestions/) which was posted by someone who was using a hyperstar and thus short exposures who was wanting to advice as to how to reduce dead time waiting for dithers to settle.

There’s a lot of ‘discussions’ about needing to take longer exposures and how frequently to dither. One comment was saying to dither every frame to ensure rejection algorithms in PI worked. Don’t know if that actually makes sense as I would have thought it would depend on the proportion of subs with bad pixel of data in, but it led me to wonder whether I could live stack my short 15s subs into say 5 minute stacks, dither between stacks and use the resulting 5 min stacks in PI?

I wasn’t able to find anything definitive saying one way or the other. Is it possible to setup live stacking such that the dither occurs between stacks and not in the middle of the stack? Would this occur even if some of the subs got rejected while stacking?

Hi,

you could probably do it using the sequence editor - turn off dithering in live stacking, but have steps in the sequence to stack for 5 minutes, save, dither, repeat. See the sequencer documentation for more info on what steps are available to build a sequence up : https://docs.sharpcap.co.uk/4.1/#The%20 ... e%20Editor

You do have to be careful with the approach of stacking multiple live stack results:

* You would need to be guiding otherwise the hot pixels will streak out into lines in each individual stack
* All per frame processing (darks, flats, etc) needs to be done in SharpCap - it can't be done in processing of the saved stack images

At the end of the day, I suspect that dithering every frame is only workable on longer exposure times (maybe 60s or more) - at shorter times you will just lose so much time to dithering that the final result will be worse simply due to the fact that you have a lot less data.

cheers,

Robin