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Equipment Discussions >> Mounts

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tjugo
scholastic sledgehammer


Reged: 11/06/07

Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6164943 - 10/29/13 04:48 PM

Quote:

Quote:

Quote:

This is crazy-good ...




This was probably guided with finder scope, if so it doesn't say much.




On the contrary, I think it says it all. That's how most imagers will use the mount?

A mount that won't guide smoothly just adds to the frustration of imaging, taking up more time with PHD than with actually taking some images.

If you don't want to use a guide scope, there are plenty of mounts in the $7~10K price range that will deliver 5 minute unguided images. But I guarantee you're not going to be carrying them out every time it's clear enough to image.

This mount takes all of ten minutes to set up, polar align and star align, and then start imaging. Tear down at the end of the night is the same.

Just my humble opinion... Paul




C'mon, don't let your love for the mount cloud your judgement. A pretty flat PHD graph not even with pixel resolution is useless.

PE profile is important because you can infer how hard/easy would be to autoguide the mount.

If you like nice flat graphs just bin the guide camera, buy a guider camera with bigger pixels or get a shorter FL guide scope.

This is a surprisnsitly good mount for the price, I had one of these mounts and it was very easy to guide, no tweaks or tuning requiere. I returned the mount because the ASCOM driver was (is?) a joke

Cheers,

Jose


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: tjugo]
      #6165294 - 10/29/13 08:22 PM

The new PHD2 can take your guider focal length and camera pixel size in microns as inputs, and graph the guiding profile directly in arc-seconds (and you can adjust the scale - just like in MaximDL).

Just when I had gotten used to super-flat guiding graphs (e.g. 0.01 rms) in PHD1..

Ah.. and PHD2 can store your calibration data so no need for that tortuous calibration exercise every time you start it up. It can also save the darks from your guide camera. And, the interface no longer locks up during long exposures with my Meade DSI. Some very nice and worthy improvements.


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6165361 - 10/29/13 09:07 PM

I'm surprised no one is posting any raw plots here...here is my unguided Zeq25 PE curve. Guide star was at 30 deg. Dec. Scope was AT72. Total payload on the mount was maybe 10 lbs. plus 1 CW. Used PHD and a 50mm guider with Orion SSAG for a pixel scale of about 6 arc-sec/pixel. Have done no tuning of the mount. This is what I got out of the box. Is this good or is this poor...I don't really know . It does guide pretty well up to 5 minute subs so far. I have a LOT more testing planned. I want to try Paul's tuneup and repeat this test. Hope the graph here is a useful data point for someone...
John

EDIT: My first plot had the wrong gear period so I deleted it. The other following plots are corrected...John

Edited by John Miele (10/29/13 10:32 PM)


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: John Miele]
      #6165393 - 10/29/13 09:25 PM

I am surprised as well, people are throwing around 8" peak-to-peak. Maybe they are looking at "Av. PE+" and "Av. PE-" which IMHO is incorrect?

The above graph shows +14 / - 12 or about 26" peak-to-peak, which, if representative of ZEQ25's means it is not the wonder-worker that many think (or want) it to be, but a thoroughly middle-of-the-road Chinese offering, with the value proposition of being light.

Can you re-post the plot but with only the first two harmonics checked? (the magnitude 100 and magnitude 80 ones) - but also change the mount type to "Vixen GP" (since the ZEQ25 has the same number of worm gear teeth as the GP, which is 144 teeth).

From your graph looks like there is a fast component with a 160-second period that's even bigger than the worm fundamental. Shades of the CGEM 8/3? the 80 magnitude component is most likely the worm fundamental, since a 144-tooth worm has a 598-second period.

To measure only the worm fundamental, only check the 80 magnitude component.

However, since the 100 magnitude component is even bigger than the fundamental, it must be accounted for when measuring PE. So the best measure of PE would be the 100 and 80 magnitude components.

All of the other components are tiny and can be ignored.


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Astronewb
Pooh-Bah
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6165433 - 10/29/13 09:51 PM

Quote:

Hope the graph here is a useful data point for someone...
John




A couple of minor points John. The worm period for the ZEQ is 600 seconds, so you need to set that in PecPrep. You have it set to 479.

After you load your PHD log, check 'Mag Period' and uncheck all the other boxes to see the raw PE in the mount.

Oh, once you tighten up the mount a bit, it will improve.

Good luck and thanks for the data.

Paul

Edited by Astronewb (10/29/13 09:52 PM)


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6165436 - 10/29/13 09:53 PM Attachment (29 downloads)

You got it! Here is the just the first two frequencies plotted and I used the Vixen GP mount option...

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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: John Miele]
      #6165441 - 10/29/13 09:55 PM Attachment (21 downloads)

And here is the frequency data. There sure is a big spike at that other frequency...is this something to try and work on? The mount seems to guide fairly well...I'll post a single cropped 5 minute sub shortly...John

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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: John Miele]
      #6165445 - 10/29/13 09:56 PM

well... there is no change in the peak-to-peak PE. So the first two harmonics are really the bulk of the PE..

If the 160-second harmonic is from the gearbox, it will not be removable (just like the CGEM 8/3 problem). I would really appreciate seeing an "after" graph once you've cleaned up the mount.

I'd be interested to see the results of others in the above format.. not because I'm nitpicking this mount (no point..) but because I've been thinking about getting one myself for travel. But honestly if they mostly have that much PE.. I'd probably go back to my plan B of looking for an old EM10/EM11/P2Z..


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve *DELETED* new [Re: John Miele]
      #6165451 - 10/29/13 09:59 PM

Post deleted by John Miele

Edited by John Miele (10/29/13 10:02 PM)


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: John Miele]
      #6165483 - 10/29/13 10:15 PM Attachment (24 downloads)

I'm not really going to do any cleaning. I'm just going to adjust the worm gear mesh and RA play and make sure I have no slop in the worm bearings. I'm also going to investigate the stronger spring option. It will be several days before I can post back an "after" comparison. Here is a single 5 minute randomly picked sub @ 100% crop...John

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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6165493 - 10/29/13 10:25 PM Attachment (15 downloads)

Hi Paul,

Here is the plot of just the Mag Period...


Quote:

Quote:

Hope the graph here is a useful data point for someone...
John




A couple of minor points John. The worm period for the ZEQ is 600 seconds, so you need to set that in PecPrep. You have it set to 479.

After you load your PHD log, check 'Mag Period' and uncheck all the other boxes to see the raw PE in the mount.

Oh, once you tighten up the mount a bit, it will improve.

Good luck and thanks for the data.

Paul




Edited by John Miele (10/29/13 10:29 PM)


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Astronewb
Pooh-Bah
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: John Miele]
      #6165498 - 10/29/13 10:31 PM

Quote:

You got it! Here is the just the first two frequencies plotted and I used the Vixen GP mount option...




You're getting there. But the Z is not a Vixen. In PecPrep, under mount types, create a type 'ZEQ25', set the worm period to 600 seconds, just '1's on the rest.

In the 'Tag' box, delete any reference there, they are for the common Synta mounts and don't apply to the Z. (I see that gear 5 entry in the drop down box..shouldn't be there)

Hit 'Save changes' and the ZEQ25 will appear in the menu.

You can enter the number of worm teeth (144) but since PEC is not permanent in the Z mount, I can't see any reason for creating a PEC curve.

If you can make those changes and post up just the 'Mag Period' results, I'd like to see it?

Oh, and here's a link to a 70 minute guided exposure taken (by mistake) off the ZEQ: http://www.flickr.com/photos/astronewb2011/8719442364/

Thanks...Paul

Edited by Astronewb (10/29/13 10:37 PM)


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6165530 - 10/29/13 11:43 PM

For purposes of PECPrep, the Z is a Vixen, with a 598-second worm period (not 600-second). All that PECPrep cares about is the number of worm teeth. Since the Z has 144 teeth, its worm period is (86164 / 144) = 598 seconds.

You can use the corrected King rate so (86188 / 144) = still 598 seconds.


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6166996 - 10/30/13 06:17 PM Attachment (10 downloads)

I made the plot Paul asked for and I think Orlandico is right. There does not seem to be any difference. One point to note: when I open PECPREP and uncheck everything but the Mag Period box, the data terms (max and min PE, etc.) all become zero. But if I move to another tab and then back to the main page, the data fills in. I do not know if this is a PECPRO glitch or if it affects the answers. But here is the plot anyway.

I think however, as Pauls images show and many others as well, that regardless of the starting raw PE plots, this mount responds to autoguiding very well and can produce some nice images. But I know we all love to deep dive into this type of thing!

John


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cloudywest
member


Reged: 06/15/13

Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6167229 - 10/30/13 08:25 PM

Quote:

Since the Z has 144 teeth, its worm period is (86164 / 144) = 598 seconds.
You can use the corrected King rate so (86188 / 144) = still 598 seconds.



The true peroid is 23.9344699*3600/144=598.36. Many people include me use 24*3600/144=600


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Astronewb
Pooh-Bah
*****

Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: cloudywest]
      #6167309 - 10/30/13 09:03 PM

Thanks John, just wanted to make sure PecPrep was behaving, and obviously it is. Orly is the guru of Pec, no doubt.

Cloudywest is the guru of mathematics, my hat's off to you.

I'll use the 24*3600/144=600 too, not because I can do the math, I just like round numbers...:)

Thanks all, for the info. I'm still waiting for a night clear enough to actually run a 50 minute raw PE exercise.

Paul


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Astronewb
Pooh-Bah
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6171215 - 11/01/13 10:54 PM Attachment (6 downloads)

Quote:

Take the mount somewhere you can drift align it properly and repeat the test, and not make any assumptions that is 5 seconds peak to peak.




Well, I was hoping for about 5 arc-seconds, peak to peak but that's not how it turned out. Guess I'll have to settle for about 2 arc-seconds average with 7 arc-seconds peak to peak, bummer.

Guiding scope was a Borg 50/250mm and a Lodestar. Guiding was disabled after calibration and a new PHD log file created. Declination was compensated for (+42).

This is with a mount polar align and a One Star align. Life is too short to drift align. Astro Tech AT6RC in the mount with the Borg 50mm piggybacked in its normal position.

Larger res on Flickr:

ZEQ_raw__PE_110113 by Astronewb2011, on Flickr

Hope the info helps,

Paul

Edited by Astronewb (11/01/13 11:08 PM)


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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6171306 - 11/02/13 12:27 AM

Correct me if I'm wrong, is this actually measured using Borg 250mm FL?
Is graph compensated for FL of the main scope?

Edited by orion69 (11/02/13 12:29 AM)


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Astronewb
Pooh-Bah
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: orion69]
      #6171338 - 11/02/13 12:56 AM

Quote:

Correct me if I'm wrong, is this actually measured using Borg 250mm FL?
Is graph compensated for FL of the main scope?




I've asked on a few forums, and have been informed, the correct method is the focal length of the guidescope, not the imaging scope.

Makes sense to me, since PHD is gathering the data through the imaging scope.

Perhaps someone has some other information or can add some information?

Best...Paul


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6171397 - 11/02/13 02:32 AM

1) interesting that your mount also displays the 200-second harmonic that is very strong (in John's case it was 160 seconds), in your case almost as strong as the fundamental.

2) what is the reported PE with only the 584-second component checked? and with the 584- and 200-second?

Can you post the PHD log file? (as alph would say, where's the logs..)


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