Sharpcap Pro & PHD2 dithering amounts ?

[Cliff]

Hi all,

I have recently started guiding and its a game changer for me anyway so thought I'd try dithering it took out about a 1 megapixel chunk out of the frame on the first dither cycle.Not good!

I am using a 530mm main scope with a 533mc camera and a QHY Miniguidescope with a Lodestar X2 camera. All on a Vixen SXD2 Mount.

I can do the trial and error but surely there is a way to calculate how much dither to set, I have PHD2 at default 1.

Appreciate ant ideas, solutions. Yes a larger guidescope might help but I have to move my gear every night.

Cliff

[Startrek]

I don’t use Sharpcap pro but I read a few posts in the Sharpcap forum and they mentioned it will only dither in Live stacking mode ??
I use APT which is set up perfectly for dither commands from PHD2 and has a dither setting table you can use to calculate your total dither
Generally as a rule of thumb you want to dither about 8 to 10 pixels in each frame
A/ Calculate your Main Imaging Camera pixel scale -
Camera Pixel size uM x 206.3 / focal length of telescope = ?? arc sec per pixel

B/ Calculate your Guide Camera pixel scale -
Camera Pixel size uM x 206.3 / focal length of guide scope = ?? arc sec per pixel

Divide A over B to get your multiplier or ratio C

Set dither scale to 1 in PHD2

Find out in Sharpcap Pro it’s dither command scale ( if it even has one ?? )
For Example -
Dither 1 = 0.5 pixel
Dither 2 = 1.0 pixel
Dither 3 = 2.0 pixel
And so on.....

And then multiply C and a Sharpcap Dither scale to end up with a pixel amount close to 8 to 10 pixels

Hope the above makes sense

[Nikolas]

I didnt understand the explanation but the easiest way is to try 1-3 pixels, it doesnt really matter in the long run as the stacking sorts it out.

[chromus]

Don't get too wound up in dithering for the 3.2 version of sharpcap its all going to change with 3.3.

3.3 is available in Beta at the moment, I recommend having a look at that rather than playing around with the livestack only version.

[Cliff]

Thanks Martin,

Appreciate the detailed description,
I mainly use Sharpcap as it doubles as a live stack and i can still save the raw frames. Not sure it has a dither scale either will check.
I do have APT will give that one a go as well, was doing ok till i enabled dither just a matter of getting the right settings I guess.

Cliff

[Cliff]

Thanks Nik,

Its a matter of working out the settings for the set number of pixels shift, as I have it moving way too far about 10% of the 9M pixels on the 533mc.

[Cliff]

Hi Phil,

I am actually using the Beta 3.3 didn't realise the dither could be used outside of livestack.

[chromus]

Its in the new sequencing wizard.

[Cliff]

Ok thanks for that