Alignmaster with Guidescope?

[Richie092]

Hi All

I have recently started using alignmaster to obtain what I think is very good polar alignment. At the moment I pop the QHY5II out of my finderguider and use it in the ED80 where the Atik normally that I use for imaging sits and then along with sharpcap I polar align. I then reassemble everything to attempt imaging through the Atik.

I am thinking about using my ST80 as the new finderscope as firstly I already have one and secondly, I like having a finderscope to help me with the 2 star alignment. I also want to nail the ST80 as a guidescope for possibly imaging with my 200p in the future.

My question is this. Can you polar align with a scope that you are not imaging with or do I have to use the ED80? I can't see any good reason that I shouldn't be able to but the not perfect alignment of the 2 scopes may be an issue.

It would make life easier if I could permanently assemble the 2 scopes, 2 cameras and all the cabling securely then I can set up a lot quicker. If I mark the place that the ED80 dovetail sits in the mount puck and also where the weights go I think I could get my set up down to just before the clouds roll in instead of a couple of minutes after!

Cheers

Richie

[brantuk]

"Can you polar align with a scope that you are not imaging with or do I have to use the ED80?"

Hi Richie - it's the mount that gets polar aligned - rather than the scope - the HEQ5 has a polar scope through it's axis. The ST80 is a good choice for guide scope - I use one and I've never heard of anyone not being able to acquire a guide star with it.

You can use a "side by side" dovetail bar to mount the ED80 alongside the ST80 - or you can piggy back the ST80 on top of the ED80 rings. Some folks prefer the second option because it's less involved to balance up. Hth

(You can use the 200P to image with an ST80 piggy backed but watch the weight - it may be easier to do with a finder/guider which would certainly be lighter).

[Richie092]

Thank you for the reply.

So if my ST80 (piggybacked, it looks more solid in my opinion) is not perfectly aligned with the axis of the mount it doesn't make a difference? This would make life much easier.

I use the polar scope to get it as near as I can before running alignmaster. It's never "quite right" just using the polar scope.

[daz]

Hmmm....

If the scope you polar align with is not aligned to the mount axis then your alignment will be out! It is the mount axis that you are aligning to, not the scope!

Think about where the scope would be pointing in relation to the star, if the mount were perfectly aligned. It would be in the centre of the field of view.

If the scope is not aligned to the mount then the star would not be in the centre of the field of view. If you then move the MOUNT to put the star in the centre of the fov, then the mount is now pointing somewhere else!

Why do you not use the Atik to do the alignment with Alignmaster?

[Richie092]

Yeah that's what I was worried about.

I suppose I could use the Atik but it is very slow (download) and also has a very small chip so needs to be spot on with the star alignment to start with and the 2 star alignment would be easier using a finderscope to align everything in the first place.

I suppose alignmaster assumes that the scope you are using is perfectly aligned to the mounts axis but is that really the case??

[brantuk]

Piggy backing is very solid, but - as Daz mentions - the main scope needs to be in line and it helps if the guide scope is too. Does your ED80 have CnC rings? I find they are best for solidity and alignment.

I haven't used Alignmaster - but you really can't beat accurate polar alignment of the mount to counter field rotation and drift, whichever software you use.

[daz]

Ritchie

What software are you using to capture with?

[Richie092]

Brantuk - I am just using the rings that came with the ED80, they look solid enough.

Daz - I am using Artemis capture with the Atik.

[daz]

OK, so you can use a small sub-frame to reduce the download time - you'll just need to make sure your finder is accurately aligned!

[Richie092]

Forgive my ignorance Daz but what do you mean by a small sub frame? Binning?

[Ewan]

Forgive my ignorance Daz but what do you mean by a small sub frame? Binning?

Hi Ritchie, the sub frame is (if i remember) the small red square tab at the top on the left hand side of the software, take an exposure, make sure stars are visible, select Sub Frame & then if you click & HOLD the mouse button on the exposure, Artemis captured on screen, you can drag a box around a star, this 'section of the picture as it were will download quicker.

Sub frame is also good for focusing, use as above then use the ZOOM slider option to blow that section of the exposure up.

Hope that helps.

[Richie092]

That is really handy to know, thank you.

I am going to check the main imaging scope for cone error first so i know it is perfectly aligned to the axis. Then I think I will pop the ST80 on just to see how far out it is. At least using the ST80 to guide will give me back my finder scope so I can hopefully get the small chip on target.

[daz]

Thanks Ewan - sorry Ritchie, got tied up and forgot to come back....!