Sharpcap PA and Lodestar X2

[groberts]

I'm planning to use Sharpcap for Polar alignment, which gets good reviews, using a Starlight Express Lodestar X2 mono guide camera, combined with a William Optics 200mm FL x 50mm guide scope, which I calculate provides a FOV of 1.85 x 1.38 degrees. I've been using this set-up successfully with PHD2 for sometime.

Given the above parameters + before proceeding further with Sharpcap I wanted to confirm: 

1. Will the pixel size of 8.6 x 8.3 nm, which is not square, work OK with Sharpcap and plate solving, which I understand is an integral part of the polar alignment routine? 
2. Will the installed ASCOM driver for this camera used with PHD2 be OK with Sharpcap or do I need something else - if so which one?

Thanks, Graham

[cjdawson]

I use the Sharpcap Polar alignment with my Starlight Express Superstar connected to a SkyWatcher ST-80 without any problems.   In fact this has been giving me the best polar alignments that I've ever had.

I tend to use 4 second exposures, just to make sure that the software don't have any problems seeing the feinter stars in the region.

As long as SharpCap can take an image I'm sure that you'll be just fine.

 

[groberts]

That's encouraging, thanks.

Graham

[Jkulin]

I use my Lodestar X2 with Sharpcap and prefer it rather than the QHY Polemaster software as I think it is more accurate and easier to read.

[groberts]

On 24/05/2019 at 16:22, Jkulin said:

I use my Lodestar X2 with Sharpcap and prefer it rather than the QHY Polemaster software as I think it is more accurate and easier to read.

Thanks John, sounds great - can you confirm:

1. As the X2 does not have square pixels, can you confirm what size you input for the purpose of using Sharpcap / Polar Alignment / Plate Solving;
2. Is there a specific ASCOM driver required or as there's already that works with PHD2, will this do the job?

Graham 

[fwm891]

On ‎23‎/‎05‎/‎2019 at 21:46, groberts said:

I'm planning to use Sharpcap for Polar alignment, which gets good reviews, using a Starlight Express Lodestar X2 mono guide camera, combined with a William Optics 200mm FL x 50mm guide scope, which I calculate provides a FOV of 1.85 x 1.38 degrees. I've been using this set-up successfully with PHD2 for sometime.

Given the above parameters + before proceeding further with Sharpcap I wanted to confirm: 

1. Will the pixel size of 8.6 x 8.3 nm, which is not square, work OK with Sharpcap and plate solving, which I understand is an integral part of the polar alignment routine? 
2. Will the installed ASCOM driver for this camera used with PHD2 be OK with Sharpcap or do I need something else - if so which one?

Thanks, Graham

Graham, Perhaps I've miss read this but surely you'll use your main optics to do your alignment with SharpCap (or any other software). If your guidescope isn't perfectly aligned with the main scope then although its adequate for guiding it will introduce errors when calibrating your PA?

[Jkulin]

Graham I must apologise, that will teach me to work and reply at the same time.

I don't use my lodestar for polar aligning I use my polemaster with sharp cap and it is that which works better than the polemaster software.

I sincerely apologise for the confusion.

[groberts]

OK got it, so use the main OTA for alignment?

As you're then using the guide scope with PHD for guiding anyhow, wouldn't such a misalignment between the OTA and guide scope then introduce guiding error anyhow, which is what I'm trying to improve?    

In that case I need to check the FOV, which I believe is max 5 degrees for Sharpcap? 

 

 

[Jkulin]

Graham, I don't think you'll be able to use your main OTA for the polemaster alignment as I don't think the field of view is big enough

I just use my polemaster and then use the sharpcap for the alignment, works perfect.

[groberts]

John - I'm now confused, I thought the whole point of the Sharpcap PA was that it works so long as you're within 5 degrees FOV of the Pole star and, I had thought that could also be using the guidescope - though I see Francis's point regarding guidescope / OTA alignment error.

Using the ZWO 1600 + WO GT 81 OTA my FOV is 2.12 x 1.60 degrees and the guide scope with the Lodestar is 1.85 x 1.38 degrees.

So what are you using Sharpcap with to refine the alignment - your OTA + if so what is the FOV?

Graham

    

[dave_galera]

31 minutes ago, groberts said:

John - I'm now confused, I thought the whole point of the Sharpcap PA was that it works so long as you're within 5 degrees FOV of the Pole star and, I had thought that could also be using the guidescope - though I see Francis's point regarding guidescope / OTA alignment error. 

Using the ZWO 1600 + WO GT 81 OTA my FOV is 2.12 x 1.60 degrees and the guide scope with the Lodestar is 1.85 x 1.38 degrees.

So what are you using Sharpcap with to refine the alignment - your OTA + if so what is the FOV?

Graham

    

Graham, I don't think the guidescope/OTA aligment has any affect on the Alt/Az adjustment of the mount, in fact as the PoleMaster is a freestanding unit then you would have the same mis-alignment problem with it, and you don't. So just use your X2 with your guide scope and use SharpCap for the alignment proceedure.

Dave

[groberts]

4 minutes ago, dave_galera said:

Graham, I don't think the guidescope/OTA aligment has any affect on the Alt/Az adjustment of the mount, in fact as the PoleMaster is a freestanding unit then you would have the same mis-alignment problem with it, and you don't. So just use your X2 with your guide scope and use SharpCap for the alignment proceedure.

Dave

Thanks Dave et al, I'll give it a go.

Graham 

[dave_galera]

Quote

 

I am just about to try this exact setup my self in the next few days, ST-80 with X2 camera and SharpCap, will let you know the result.

Edited May 25, 2019 by dave_galera

[groberts]

Ah - good luck. I'll look forwards to hearing how you get on.

[Jkulin]

4 hours ago, groberts said:

So what are you using Sharpcap with to refine the alignment - your OTA + if so what is the FOV? 

I'm just using the Polemaster Camera with Sharp Cap, not sure what the field of view is.

[dave_galera]

OK I tried using the Lodestar X2 on my ST-80 guider (400mm at f5) and even with 10s exposure there where no stars visible....ummmmmmm!!

I desperation I tried my Atik 383 on the Tak at a FL of 328mm (FOV 184 x 141 arc min)........perfect, lots of stars, plate solved with no problem, polar aligned mount, brilliant piece of software

Going to investigate where the stars have gone on the X2 tonight

 

[newbie alert]

On 25/05/2019 at 17:52, Jkulin said:

Graham I must apologise, that will teach me to work and reply at the same time.

I don't use my lodestar for polar aligning I use my polemaster with sharp cap and it is that which works better than the polemaster software.

I sincerely apologise for the confusion.

Snap, and have the same conclusion 

[cjdawson]

On 25/05/2019 at 17:34, fwm891 said:

Graham, Perhaps I've miss read this but surely you'll use your main optics to do your alignment with SharpCap (or any other software). If your guidescope isn't perfectly aligned with the main scope then although its adequate for guiding it will introduce errors when calibrating your PA?

 

I use my ST-80 to do the polar alignment for my Meade LX-90.  The Field of View is big enough to get the plate solve and it doesn't matter if the guide scope is aligned with the main optics.  It just just has to be connected to the main optics and work in sync with it.   Does not have to point the same direction.

 

On 25/05/2019 at 18:05, groberts said:

OK got it, so use the main OTA for alignment?

As you're then using the guide scope with PHD for guiding anyhow, wouldn't such a misalignment between the OTA and guide scope then introduce guiding error anyhow, which is what I'm trying to improve?    

In that case I need to check the FOV, which I believe is max 5 degrees for Sharpcap? 

 

 

Use the Guidescope for alignment, misalignment of the guidescope doesn't introduce and error.  Actually, I've never aligned me guide scope and main scope and it works great.

To polar align you should point to within 5 degrees of the pole.  As for the rest, I understand that Sharpcap have been working on it and it's now more sensetive than it used to be.  Not sure of the exact figures, but I know that my ST-80, Superstar combination is right on the limit of what it can work with.

 

On 25/05/2019 at 20:00, dave_galera said:

Graham, I don't think the guidescope/OTA aligment has any affect on the Alt/Az adjustment of the mount, in fact as the PoleMaster is a freestanding unit then you would have the same mis-alignment problem with it, and you don't. So just use your X2 with your guide scope and use SharpCap for the alignment proceedure.

Dave

The guidescope OTA alignment is not critical.   I agree, use the guide scope for alignment, it'll work great.