64 replies to this topic

[syscore]

Surprised that you find balance critical.  I found (on my EM-11) that balance was pretty indifferent.  But then again I only put an 80mm on it (albeit a very heavy for its size 80mm).

 

That M42 must be with the C11?  honestly I think an EM-200 is overloaded with a C11...

 

I could definitely tell a difference by changing the weights. in fact, I could watch the guide star elongate when I was off (balance) due to vibration. I never got a feel for it with the 11" because I couldn't get a long enough break from the clouds. Finally, I left it doing 15 sec frames of M42 and went to bed.

 

I will say this though. I had to focus manually (the horror) and it was very solid focusing. I do think, if it had been a good night, and maybe the worm issue not be there, it could handle an 11". However, maybe the balance is a sign that it couldn't. I would need a few good nights to know one way or another.

Edited by syscore, 24 October 2016 - 07:39 PM.

[Iver]

     I'm not sure if Stellarium has the ability to make a pointing model, but from the telescope control window you can open a points window. I can't imagine what else it would be for.

 

[johngwheeler]

     I'm not sure if Stellarium has the ability to make a pointing model, but from the telescope control window you can open a points window. I can't imagine what else it would be for.

 

Untitled 1.jpg

Hmm, I'm not sure; I'd need to try it. Is this part of the Telecope Control or the StellariumScope ASCOM app that you need to get Stellarium to work with ASCOM drivers? 

 

I though that ASCOM alignment for only available via EQASCOM, on EQMOD compatibile mounts. But I have no idea if this is correct!

 

I found the StellariumScope add-on a bit fiddly (it often crashed, or failed to respond), and moved to Cartes Du Ciel for this reason. I'm pretty sure this only does a single star sync as well.

 

 

John.

[johngwheeler]

I've just had a thought about my problem with Astromist.

 

During the alignment, I was *manually* moving the scope (by releasing the clutches) to move to the alignment stars. The EM-200 doesn't have absolute or dual encoders so I suspect that the software is blissfully unaware that the scope has moved, unless it is moved by slewing with the motors. This might explain why my two alignment stars reported the same position.

 

Does this sound possible?

 

John

[syscore]

Absolutely.

 

You have to slew to the alignment stars.

[Iver]

Really I have no idea what the point window does but you will need Stellarium scope.

 

I know you were not asking me your last question, but to make a pointing model the sofware will need to know where the scope was supposed to go and where it actually did go to be able to model the error. The EM- 200 encoders are attached to the worm.

[johngwheeler]

Absolutely.

 

You have to slew to the alignment stars.

I tried this last night, and yes, the position is updated if I slew to the objects. So that's one less mystery problem solved!

 

However, when I pressed the alignment button on Astromist, the app went nuts with a message flashing up "too many numbers from Goto" or similar, and I had to kill it to stop the screen flashing.

 

So my experiment wasn't successful. I will try one last time, but I think I've had it with Astromist. Even if it does work, I'd then have to use Astromist as my planetarium software and it's far less polished than Sky Safari, Stellarium or Cartes Du Ciel.

 

It was worth a go, but I don't think it's going to be good solution for me.

 

I'm going to experiment with "closed loop" gotos if I can get a plate solver to play nicely with a separate planetarium app. Maybe Sequence Generator Pro can do this? The idea would be use my guide scope with a camera to capture images for the plate solver, and use the main scope for visual use.

 

Out of interest, I set up my AVX mount last night to use with another scope. I had forgotten how easy it is to get good goto accuracy with a 2+2 alignment, even with an "eyeballed" polar alignment. If only I could have the Celestron handset software with the Takahashi mechanical quality!

 

John.

[orlyandico]

I've tried that (guide camera for plate solving). The problem is the guide chip is so small, the guide camera is generally not that sensitive, and the field of view is too small.  To get a decent field, you want something like a finder guider. But the finder guider is 50mm and doesn't capture that many stars for the plate solve.

[johngwheeler]

I've tried that (guide camera for plate solving). The problem is the guide chip is so small, the guide camera is generally not that sensitive, and the field of view is too small.  To get a decent field, you want something like a finder guider. But the finder guider is 50mm and doesn't capture that many stars for the plate solve.

Yes, I was thinking that this could be problem too. I have a couple of guide scopes (400mm & 182mm focal length) and some planetary cameras. I'll just have to experiment.

 

John

[orlyandico]

I did use Astrometry (astrotortilla) which is a blind solver. With 5-second range exposures and a finder guider, I could only find maybe half a dozen stars. Good for guiding, not good at all for blind solving.

 

If you have a non-blind solve (use the mount's reported RA/DEC as the starting position) you might get solves.

[syscore]

John, taking off the control box is pretty straight forward. The 4 screws on the corners, and one grub screw in each collar for the encoders, and the whole thing comes up. In this picture you can see the LED that is nothing but two stiff wires holding the LED out into the DEC housing cavity. It would be easy to adjust (bend).

 

[johngwheeler]

John, taking off the control box is pretty straight forward. The 4 screws on the corners, and one grub screw in each collar for the encoders, and the whole thing comes up. In this picture you can see the LED that is nothing but two stiff wires holding the LED out into the DEC housing cavity. It would be easy to adjust (bend).
 
EM-200-Led.jpg

I did try taking the control box of my EM-200 when I got it, and couldn't move it after undoing the 4 main screws. I didn't see the grub screws on the encoder shaft - so thanks for this! I think the LED has blown, but I should be able to find a replacement easily enough. I might give the PA scope another go if I got this working :-)

Thanks,

John.

[syscore]

Just loosen the grub screws a turn or 2, and leave the control box complete (just take out the 4 long screws to get it off). If the LED is blown, there is plenty to solder a new one onto, and put some shrink wrap on each wire, that can slide up and cover the joins when you are done.

[jrbarnett]

I am in Singapore where there's no view of Polaris either.

 

My "solution" is simple - when doing a long slew e.g. with Sky Safari, instead of slewing to the object, I slew to a bright star near the object.

 

As expected, the slew will be off.  Then I center the star with the finder (and then the main scope) and resync Sky Safari.

 

Now, the short slew to the nearby object of interest will be pretty accurate.

 

It's annoying, but works.  Don't hold your breath waiting for a multi-star solution. You could use Cartes du Ciel and Chuck's ASCOM driver. That will allow two-star aligns. But it needs a PC.

I do this too for long sessions with the EM-200.

 

I'm not imaging, so I do a simple polar align using the polar scope, and a one-star using Sky Safari, bit over a long session error tends to creep into the initial alignment.  The local sync method works great.  It lets me put targets within the middle portion of a 138x 0.75 degree FOV.

 

- Jim

[johngwheeler]

I am in Singapore where there's no view of Polaris either.
 
My "solution" is simple - when doing a long slew e.g. with Sky Safari, instead of slewing to the object, I slew to a bright star near the object.
 
As expected, the slew will be off.  Then I center the star with the finder (and then the main scope) and resync Sky Safari.
 
Now, the short slew to the nearby object of interest will be pretty accurate.
 
It's annoying, but works.  Don't hold your breath waiting for a multi-star solution. You could use Cartes du Ciel and Chuck's ASCOM driver. That will allow two-star aligns. But it needs a PC.

I do this too for long sessions with the EM-200.
 
I'm not imaging, so I do a simple polar align using the polar scope, and a one-star using Sky Safari, bit over a long session error tends to creep into the initial alignment.  The local sync method works great.  It lets me put targets within the middle portion of a 138x 0.75 degree FOV.
 
- Jim

This is what I've ended up doing, but I'm still interested how Cartes Du Ciel can do 2-star alignments on a Tak mount (without reuquiring EQMOD features).

John