Anyone using EQMod polar align tool and a webcam?

[Reggie]

Hi all, I've just done the astronomyshed skywatcher EQ polarscope webcam mod:

I also noticed this video that shows how to use the EQMod polar alignment tool:

I'm wondering if anyone has used this combination of software and hardware together and did it produce decent results?

It seems that the setting circles are almost redundant if you use the EQMod polarscope alignment tool?

Looks like it will make things much much quicker, now all we need is a mod that adds motors the alt/az adjustment bolts and get it to do it all itself

Regards,

Reggie.

[DIYASTRO]

Reggie,

I have made one of these but as yet not used it! Mine is for the polarscope used in the alignmate for meade wedge and I used some 1.25 filter housings and a little turning on the lathe to couple the scope to the camera. Most of my scopes are fork mounted you see.

When my back is better I may attempt to drag out one the beasts and try to align it with the EQASCOM. No obsy yet but working on that one!

Boyd

[Gina]

I've done the webcam mod and planning to use the EQMOD polar alignment method when conditions permit. I agree, it looks a good way to do it

[Reggie]

Annoyingly, I've managed to snap the lip bit on one of the legs, not sure if it's going to affect things or not, I guess it's a question of waiting for a clear night and see what happens

[chrisshillito]

Can't say I've really ever seen the need for a dedicated polar scope cam. I just use a star diagonal over the end. With the end removed to get closer my eye closer to the mirror I get sufficient field of view to do all the necessary adjustments from a seated position (but of course the image is flipped).

Folks down under might find a webcam ideal though as it will bring out those much fainter pole stars that EQASCOM uses in its alignment routine.

Chris.

[Gina]

That's a thought Do you just hold the diagonal in your hand, or use some sort of adapter to fix it to the polar scope?

[Reggie]

Unfortunately, I have a stomach disease, bending over can be rather uncomfortable for me, so I'm doing this to accomodate doing as little bending as possible, I also get tired very quickly too. Can't use a chair at my home site either. Last time I took a scope out (nexstar 6SE) my legs were aching for days, that was using a chair on the driveway (south facing, fine for an Alt/Az, not particularly brilliant for an EQ mount).

I've just had a look through a diagonal, don't really fancy taking it apart to get a full field of view. I guess dismantling the diagonal is necessary given that I get a field of view that's large enough to give me a decent view of the 'o' in octans

[BlueAstra]

Have you had a look at AlignMaster polar alignment software? Works a dream for me.

[Reggie]

Chris, Am I right in thinking that your polar alignment routine pretty much does away with the setting circles? It seems that they are used merely to indicate the home position?

I'm also wondering whether you've compared the results from your alignment tool to anything, say, drift aligning?

[Reggie]

BlueAstra, thanks for that, I haven't tried alignmaster (mainly because I haven't had a decent chance to get the EQ mount out in anger for quite some time.)

2 big advantages of chis's tool are, it's free and I don't have to install yet another app, I guess I'll have to try both methods

[chrisshillito]

That's a thought Do you just hold the diagonal in your hand, or use some sort of adapter to fix it to the polar scope?

Its standard, cheapo, 1.25" star diagonal and I just use it "the wrong way round"- so end the usually takes the eyepiece goes over the polar scope with the locking screw holding it in place. I unscrew the metal barrel from the projecting other end.

Chris

[chrisshillito]

Chris, Am I right in thinking that your polar alignment routine pretty much does away with the setting circles? It seems that they are used merely to indicate the home position?

I'm also wondering whether you've compared the results from your alignment tool to anything, say, drift aligning?

Hi Reggie.

Yes, the setting circles are not part of the process at all. The alignment tool really isn't doing anything particularly clever - its just using the PC to work out where the Polaris bubble should be rather than using the RA setting circle and polar scope dial.

Accuracy won't be as good as drift aligning but then again it seems to me that many folks are unnecessarily obsessive about polar alignment. At the end of the day you only need a level of accuracy such that your images aren't compromised.

Chris.

[Reggie]

Just tried that Chris, I can just about see the whole of the polaris circle now but nothing like a useful view unfortunately. Just to add, I was just trying to get an idea of what kind of accuracy can be achieved, I agree polar alignment seems almost a fine art to some people, however, just using setting circles I've always gotten adequate results, coupled with EQMods alignment routines and a guidescope.

I like the way you describe it as 'not doing anything clever' It's doing the maths and giving us a semi automated alternative to using setting circles, it's another layer of difficulty removed for those of us with non-permanent setups. I wonder what size stepper motors it would take to move the alt/az bolts.....

[Black Knight]

Its standard, cheapo, 1.25" star diagonal and I just use it "the wrong way round"- so end the usually takes the eyepiece goes over the polar scope with the locking screw holding it in place. I unscrew the metal barrel from the projecting other end.

Chris

That sounds like a cracking idea Gromit! I'm going to have to give this a go!

[Gina]

Now if I had a 1.25" diagonal I could try that but mine is a 2" version. I'll stick with the webcam My poor old body isn't flexible enough to get down and look up into the ep of the polar scope.

[malc-c]

I wonder what size stepper motors it would take to move the alt/az bolts.....

LOL - I've been thinking that for some time... can't be too hard as a lot of folk use steppers and threaded bar for DIY CNC machines. But wouldn't it be good to hook up a web cam and point the scope at Polaris so it's in the field of view, run a bit of software (EQASCOM per say ) - and it then drives the steppers, using the web cam to track Polaris until the mount is perfectly PA

[Reggie]

Indeed, looks like a simple plate of some kind that sits between the tripod and the mount would fairly easily take some stepper motors but I wonder about coupling, certainly doesn't look practical for directly driving, would need some kind of gearing.

[Gina]

Now don't get me started - you all know I can't resist a challenge

[chrisshillito]

Just tried that Chris, I can just about see the whole of the polaris circle now but nothing like a useful view unfortunately.

Yes the FOV isn't great but is big enough to show the all important central circle. I find there is sufficient play to tilt the diagonal slightly if I need to scan the outer edges.

[Earl]

I find the big problem with polar aligning is caused by the thickness of the etching or print on the reticule lens, its way to thick to be accurate, but I have learned its really not that important if your guiding, as long as its more or less on, the guiding will solve any problems.

[Reggie]

Earl, could you explain a little bit more please?

[malc-c]

Earl, could you explain a little bit more please?

I think what Earl is on about is that the circle with the bubble is quite thick, and the diameter of the bubble is far greater than Polaris that it there is enough error that can creep in, which whilst is OK for visual, could cause issues when imaging. However these errors should be small enough that the guiding scope / software will be able to cope

[Reggie]

Ahh, I wasn't sure, thanks Malc so would de-focussing and making polaris fit the circle be useful in addressing that?

[chrisshillito]

But if you want to be really accurate and take into account precession then don't really want to put it dead centre in the circle - see attached.

Chris

[Reggie]

Thanks Chris, so putting it at 1/2 way between the 'polaris' circle and the intersecting like looks like a good bet.