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Ovision upgrade

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#51 dawziecat

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Posted 29 May 2013 - 10:13 AM

Terry, I still bet it's not good enough to make you regret buying the AP1100 :)


Well, I'm still waiting of course and likely will be for quite some time yet. My cheque book is ready . . . but A-P is not. :(

If I thought I could ever come close to your results at 4 min and 1625mm, I likely would have never considered a more costly mount.

In the meantime, I play with my RAPAS! :)

#52 gdd

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Posted 29 May 2013 - 12:01 PM

Hi Hilmi,

Great results! PEC may take you the rest of the way.

I have been getting good results with my OPW on M51 with 3 minute exposures at 1000mm with my Canon 350D when I remember to tighten everything down, get a good PA, and maintain consistant east side bias with my string/weight contraption. I did one 6min exposure by mistake that had slight trailing due partly to drift.

Gale

#53 Hilmi

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Posted 29 May 2013 - 01:04 PM

Gale I'm not done yet. I still have the gearbox replacement then the ballance tuning. I also have a sticky main dec bearing to work on.

Only then will I be happy.

#54 pfile

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Posted 29 May 2013 - 06:38 PM

I no longer have any regrets buying the G11 other than the time wasted troubleshooting.


that's the thing though, how many months have you been at this? i think new users need to be aware of this.

regardless, congratulations are in order for what you've achieved. nice work.

#55 Raginar

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Posted 29 May 2013 - 07:28 PM

Rob, he's been at this now for about 9 months. And, it's taken significant tinkering to get it to this level (ovision, new worm block..).

I guess the biggest take away is that you can do it if you're willing to spend the cash. That's something you can't say about a CGEM or an iEQ45 since they lack the upgrade path.

Hilmi, that's an awesome picture.

#56 gdd

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Posted 29 May 2013 - 07:52 PM

Hi Hilmi,

Did you start out with the standard wormblocks or the OPWB?

Gale

#57 zytrahus

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Posted 29 May 2013 - 11:03 PM

Terry, I still bet it's not good enough to make you regret buying the AP1100 :)

But yes, I was amazed. Today I found somewhere hidden on the www.gemini-2.com site how to actually make the PEC curve you create in PEMPro stick to the Gemini II. I will try that process today and see how round the stars turn out after that. There is still some elongation. It's not much, I know that with stacking most of it will go away but I still want to see how round I can get the stars to be natively without processing. That might even be a collimation defect and not a tracking issue.


if you got a link for that PEC trick ^_^ I am interested :)

#58 Hilmi

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Posted 30 May 2013 - 12:10 AM

Gale,

I started out with the OPWB, which theoretically should be able to give good results but is just too picky about adjustment.

Stephen,

I did not get a chance to validate if this works, but basically, after you train PEC in PEMPro, you go to the Gemini ASCOM driver at the bottom right of your windows screen. You right click on the Gemini icon and choose advanced settings. Under advanced settings, you go to the bottom of the screen and you will find a little tick box that says "include PEC data" then click apply. This will download all your settings from the driver to the mount including the PEC curve. Yesterday I forgot to do a test by powering off the mount and restarting it, but I did confirm that the PEC buttons where visible in the hand controller after I selected this option.

Pfile, my advice with future G11 buyers with dreams of imaging is not to waste time and budget for the Ovision worm upgrade right from the start. It is my personal opinion that unless you are imaging at short focal lengths, this is a mandatory upgrade. I am not sure, but I even feel the slewing is quieter after installing the new worm.

#59 orlyandico

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Posted 30 May 2013 - 02:35 AM

i'm not so sure about that. i know someone who has a stock G11 and his measured PE is way less than 10" p-p.

he's imaging quite happily with it, no tweaks or anything.

#60 Hilmi

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Posted 30 May 2013 - 02:39 AM

At what focal length is he imaging and what pixel size?

At the pixel scale I had, with a smooth PE curve of 16 arcseconds peak to peak I still had elongated stars because the original worm gear seemed to be more sensitive to bad balance and wind due to the excessive backlash I had to leave to get that smooth PE curve.

On the other hand, with this upgrade, I had yesterday imaged one of my best images in terms of star roundness unguided. Once I get my guide came back, I bet I can get even tighter stars.

At 360 mm, I was able to image with the original worm gear unguided. I suspect that it would also work very well up to around 1000 mm, but honestly, at the 1600mm - 2000mm, the original worm gear and OPWB were no fun to use and almost made me quit the hobby. There have also been variable reports of recent worm gears being sub par. Maybe I had been unfortunate to have those worm gears (including the replacement one that i had ordered to replace the one I damaged while trouble shooting the mount).

#61 orlyandico

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Posted 30 May 2013 - 03:38 AM

you're right Hilmi, he was at about 950mm (ES127).

#62 Hilmi

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Posted 30 May 2013 - 05:37 AM

You see, I consider that a short focal length (relatively speaking). So I still stand by my recommendation that the cost of the Ovision worm gear be budgeted for if somebody plans to buy a G11 for imaging.

#63 orlyandico

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Posted 30 May 2013 - 05:40 AM

.. at long FL.

from what i see a significant fraction of people doing AP, do so with refractors.

#64 Hilmi

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Posted 30 May 2013 - 06:09 AM

I'd say most people actually use 8" Meade or Celestron SCTs

Edit: That's besides the point. If for a $500 + shiping increase in the price of the price you can improve the PE of the mount 1/4 the original PE with minimal effort from the user, why not. We spend $500 on far less useful imaging accessories.

#65 Raginar

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Posted 30 May 2013 - 07:24 AM

Hilmi,

I agree. 500 bucks to most of us is alot of money but we do spend as much as that on things like AO or an OAG.

Your results are awesome ;).

#66 pfile

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Posted 30 May 2013 - 10:16 AM

the thing is, i believe there is something wrong with the recent batch of G11s. 30" pk-pk is way out of spec historically speaking.

to be honest the absolute value of the PE is not really a problem. what's a problem are spots in the worm that have a slope too great to be corrected by autoguiding, which is what got me.

#67 Raginar

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Posted 30 May 2013 - 10:26 AM

Rob,

There does seem to be a rash of 'bad' stories lately. I wonder what changed.

#68 saadabbasi

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Posted 30 May 2013 - 11:07 AM

My G11, bought in 2009, had 8" peak to peak (stock worm). Never upgraded to Ovision or the new worm Losmandy offered either.

#69 Hilmi

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Posted 02 June 2013 - 06:12 AM

Gearboxes are in. I've got to fly to Abu Dhabi for work tonight, so I doubt I will get the modification done before the Thursday. How unfortunate. I was looking forward to getting this done tonight.

RS components delivered the gearbox, and the motor pinion gear has a smaller hole than what was mentioned in the specs. I don't have the correct tools to ream it to size since the hand 1/8" hand reamer I purchased wont go through the hole, it's too tight of a fit.






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