Telescope Reviews: +- 1 arc second Periodic Error G11 mount and TDM

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Equipment Discussions >> Mounts

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gdd
sage

Reged: 11/23/05

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4597844 - 05/23/11 09:27 AM

Quote:

I have the standard worm that came with the mount 5 years ago. No upgrades or adjustments to it.

If you were to upgrade to the high precision worm, or even the OPWB, and improve your PE from 14 arcsec p-p to 7 arcsec p-p, is it likely your PE with TDM may improve to 1 arcsec?

Gale

Post Extras:

D_talley
Carpal Tunnel

Reged: 07/07/05

Loc: Richmond VA

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: gdd]
#4597846 - 05/23/11 09:30 AM

Quote:

Quote:

I have the standard worm that came with the mount 5 years ago. No upgrades or adjustments to it.

If you were to upgrade to the high precision worm, or even the OPWB, and improve your PE from 14 arcsec p-p to 7 arcsec p-p, is it likely your PE with TDM may improve to 1 arcsec?

Gale

Yes, I bet it would get below 1 arc sec. But you would not gain much with that because of seeing.

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tomo
professor emeritus

Reged: 06/14/10

Loc: Shelby Twp, Mi

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4597878 - 05/23/11 09:45 AM

Phew Dwight! You saved me from hours of fine tuning to try an match 0.4 arcsec.

Edited by tomo (05/23/11 09:47 AM)

Post Extras:

dawziecat
Pooh-Bah

Reged: 10/20/10

Loc: Rural Nova Scotia

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4597898 - 05/23/11 09:52 AM

I am perplexed at this thread.

There is no such thing as perfect alignment, nor perfect "orthogonality" for that matter.

So the mount still has to be guided in dec at least.

The mount is still as susceptible to bad tracking due imperfect alignment and cone error as it ever was.

The guider will have to work less in RA correction but there will still be the other errors.

What has really been gained?

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Tapio
Pooh-Bah

Reged: 09/24/06

Loc: Tampere, Finland

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: dawziecat]
#4597937 - 05/23/11 10:03 AM

I've done polar alignment with WCS and it's so accurate that I can take 4-5 min subs with only RA guiding.

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jmiele
Patron Saint?

Reged: 12/04/10

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: dawziecat]
#4598006 - 05/23/11 10:37 AM

dawziecat

The thread title only stated +- 1 arc sec PE G11. My first question was concerning auto-guiding. Not sure it was Dwight's intent say you didn't need to auto-guide. Just that PE could be reduced to 1 arc sec in his experience using this device.

All mounts require some level of guiding - even the best in the world. What manufacturers state to show how good their mounts are is PE. Here is something that can "possibly" improve PE beyond the best out there for considerably less money. I think that's all he was saying.

Joe

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D_talley
Carpal Tunnel

Reged: 07/07/05

Loc: Richmond VA

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: jmiele]
#4598098 - 05/23/11 11:24 AM

At the 980mm that I am imaging at, I don't need to guide for 5 minute subs.

If I was using my Meade 14 at 3550mm, I would be guiding. Different mounts and built in errors may require you to guide. This is just my experiences with TDM.

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mclewis1
Thread Killer

Reged: 02/25/06

Loc: New Brunswick, Canada

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4598468 - 05/23/11 02:42 PM

Dwight, Good points ... and that I believe is real bottom line. Not black or white, good or bad. The TDM is effective and whether it makes sense for someone is based on their specific requirements.

Having a discussion about the product brings out the various characteristics and each of us then needs to weigh them against our requirements.

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Kaizu
sage

Reged: 08/17/07

Loc: Finland

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4599949 - 05/24/11 09:54 AM

I happened to have better luck with my G11. The original PE is ca. 5" from peak to peak. I can take 1 min, (some times 2 min)unguided exposures with TAL250K (fl 2137mm). Still I need auto guider because of the atmosphere refraction. I use the LVI-smartguider. Only if my targets are near zenith, I dont need the guider.
But anyway, the +/- 1" is an great achievement without guiding. I wanted that precise encoders also.

Kaizu

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j.w.white
sage

Reged: 07/18/09

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: D_talley]
#4601392 - 05/25/11 01:07 AM

Thanks for the pictures and the description Dwight! I wonder though - which would be the way to go to save a CGEM from an increasingly likely mount replacement, the TDM (assuming they make an adapter for it yet) or Adaptive Optics? They are both in the same price range, and both offer much better performance than the mount is capable of natively. I'm not sure that the CGEM's gearing is good enough to make use of the TDM's corrections, which would seem to give AO the edge.

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John Wunderlin
Vendor - Spike-a Focusing Mask

Reged: 10/01/04

Loc: Mineral Point, Wi

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: Benach]
#4602466 - 05/25/11 02:48 PM

I wonder if this would effectively increase the weight capabilities of the mount? It seems to me that you could 'push the envelope' a bit more with this. Very attractive- I've been thinking about doing more automated imaging in the future and it would be wonderful for me to be able to skip the guiding process.

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Mert
Post Laureate

Reged: 08/31/05

Loc: Spain, Pamplona

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: Benach]
#4602579 - 05/25/11 03:49 PM

Hi Dwight, that's for sure a spectacular result!!
Seems to work perfect right from the start.

One question I'd like to ask: the image that shows
the "brains" has a sticker on a prom stating "Serial number"

It states 2009 - 154, could that mean the micro-code
running in the V2.2 is from 2009??

Not an item since it works perfectly, just my curiousity!

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D_talley
Carpal Tunnel

Reged: 07/07/05

Loc: Richmond VA

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: Mert]
#4602734 - 05/25/11 05:11 PM

Since I bought this in 2010, the date should be correct. I think this is the latest version. No need to change anything since it just works right out of the box.

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D_talley
Carpal Tunnel

Reged: 07/07/05

Loc: Richmond VA

Re: +- 1 arc second Periodic Error G11 mount and TDM new

[Re: j.w.white]
#4602969 - 05/25/11 07:40 PM

Quote:

Thanks for the pictures and the description Dwight! I wonder though - which would be the way to go to save a CGEM from an increasingly likely mount replacement, the TDM (assuming they make an adapter for it yet) or Adaptive Optics? They are both in the same price range, and both offer much better performance than the mount is capable of natively. I'm not sure that the CGEM's gearing is good enough to make use of the TDM's corrections, which would seem to give AO the edge.

I cant give you any direction on this since I have not used a CGEM. I do want to get a AO to counter the seeing at my site. What is your PE now with your mount?

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