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Equipment Discussions >> Mounts

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Astronewb
scholastic sledgehammer
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Reged: 09/19/11

Loc: Connecticut
ZEQ25 PE Curve
      #6154720 - 10/24/13 01:18 AM Attachment (80 downloads)

Just for info, I guess some ZEQ owners and shoppers want to know how the Z Balanced mount stacks up? For $800 bucks you could do a lot worse....

This is from PecPrep V1.84 and a PHD log file from Sept 24th, corrected for DEC. I was imaging M33, guiding with a Lodestar/Borg 50mm/250mm combo. Main scope was a Borg 125SD.

This PecPrep isn't cherry-picked, I have tons of them like this, some better, some a little worse.

Hope someone on the fence for a splendid little 10 pound mount finds this interesting, and helpful.

Clear skies,

Paul


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orlyandico
Post Laureate
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Reged: 08/10/09

Loc: Singapore
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6154798 - 10/24/13 03:58 AM

but that is the error while it is being actively guided - hence that's not the true PE of the mount (see the EQ8 PE thread) but rather the measure of how tight it guides.

The PE would be measured by disabling guide outputs in PHD..


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Astronewb
scholastic sledgehammer
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: orlyandico]
      #6155283 - 10/24/13 11:02 AM

Quote:

but rather the measure of how tight it guides.




Very true Orly. If iOptron ever puts their excellent Two Star align routine back into the HC firmware, I could post a raw PE curve.

That routine reports Polar Offset, and allows you to dial out the offset to '00-00' by using the az and lat adjusters.

iOptron replaced that routine with a 'Bright Star' type routine for users that don't have a view of the pole stars (or couldn't figure out how to use the polar offset?) at the expense of users that can see the pole stars. The new routine is not even close to being accurate enough to dial out polar offset.

I have no easy way to drift align to get to that reference point, since I have no views to the West, and my view to the East has 5 streetlamps between me and the horizon, which makes selecting a suitable star frustrating, if not hopeless..:(

If I had to estimate, with my tightened mount, the resident PE is probably under 5 arc-seconds peak to peak.

But, this result is off a tripod, with just a basic polar align and a One Star go-to, and guided, which is how most of the users of this mount will be using it, so it's still relevant?

And it certainly does show how well it tracks when guided.

Clear skies,

Paul

Edited by Astronewb (10/24/13 11:06 AM)


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PGW Steve
Pooh-Bah


Reged: 10/03/06

Loc: Winnipeg, Canada
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6155436 - 10/24/13 12:25 PM

It is deceiving to see "ZEQ25 PE Curve" and then come into the thread thinking that an $800 mount makes my Astro-Physics Mach1/1200/1600 look like junk. :-P


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.


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tjugo
scholastic sledgehammer


Reged: 11/06/07

Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6155457 - 10/24/13 12:34 PM

Hi Paul,

You don't need perfect polar alignment to measure PE... PECprep will remove the drift caused by polar misalignment.

Residual Error after guiding is not very meaningful cause it is tie to seeing, guiding equipment, mount operator etc.

Just be careful to compensate for DEC when reporting tracking error.

Cheers,

Jose


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core
Pooh-Bah
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Reged: 02/23/08

Loc: Mostly in Norman, OK
Re: ZEQ25 PE Curve new [Re: tjugo]
      #6155464 - 10/24/13 12:36 PM

I'm looking forward to see the raw PE curve of the ZEQ!

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Astronewb
scholastic sledgehammer
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: tjugo]
      #6155627 - 10/24/13 01:57 PM

Quote:

Hi Paul,

You don't need perfect polar alignment to measure PE... PECprep will remove the drift caused by polar misalignment.

Residual Error after guiding is not very meaningful cause it is tie to seeing, guiding equipment, mount operator etc.

Just be careful to compensate for DEC when reporting tracking error.

Cheers,

Jose




Thanks for that useful info Jose, I will give it a shot the next time I have a break in the weather.

Best...Paul


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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6155734 - 10/24/13 03:06 PM

0.33" RMS seems to be an excellent value. That's what I get with my Mach1 and NJP, unless the seeing is exceptional.

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ramasule
member


Reged: 04/12/12

Re: ZEQ25 PE Curve new [Re: andysea]
      #6158476 - 10/26/13 12:04 AM

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=&Board=lxd55&...,,All_Forums,,&Words=&Searchpage=1&Limit=25&Main=6081789&Search=true&where=&Name=208311&daterange=&newerval=&newertype=&olderval=&oldertype=&bodyprev=#Post6082579

Mind you I haven't had a good night to get better data since.


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anat
professor emeritus


Reged: 06/03/04

Re: ZEQ25 PE Curve new [Re: ramasule]
      #6158636 - 10/26/13 04:45 AM

Could you tell me the PE in arcsec?

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ramasule
member


Reged: 04/12/12

Re: ZEQ25 PE Curve new [Re: anat]
      #6159136 - 10/26/13 12:51 PM

8 peak to peak about. Next time im out I will try for a better graph.

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Tony Finnerty
member


Reged: 03/06/13

Loc: Nevada City, California
Re: ZEQ25 PE Curve new [Re: ramasule]
      #6162511 - 10/28/13 01:19 PM

No PE curve, but two nights ago I got PHD Guiding graphs for my tuned ZEQ25 (thanks for the videos, Paul!) that looked like this consistently:



This is crazy-good for the crazy system I'm developing for winter AP from my balcony with its flexible floor boards. The tripod is set on a plywood triangle and I step on separate plywood sheets to distribute weight to minimize tilting the mount when I move. The tripod is set on three 8x8x16 inch concrete blocks standing on end for 16 inches of lift, to raise the polar scope high enough to see Polaris over my roof. I stay off the balcony during exposures.


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nomosnow
sage


Reged: 03/21/11

Loc: Fort Saskatchewan,Ab ,Canada
Re: ZEQ25 PE Curve new [Re: Tony Finnerty]
      #6163190 - 10/28/13 07:21 PM

Very nice graph indeed , Tony what declination was the object that you were imaging ?
John


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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: ZEQ25 PE Curve new [Re: Tony Finnerty]
      #6163207 - 10/28/13 07:30 PM

Quote:

This is crazy-good ...




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


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Astronewb
scholastic sledgehammer
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Reged: 09/19/11

Loc: Connecticut
Re: ZEQ25 PE Curve new [Re: orion69]
      #6163396 - 10/28/13 09:32 PM

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

Edited by Astronewb (10/29/13 10:33 AM)


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Mkofski
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Reged: 07/19/11

Loc: Greenfield, Indiana, USA
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6163419 - 10/28/13 09:45 PM

Completely agree with you Paul. My take on Orion69's comment was that using a finder size guide scope wasn't very meaningful and that a longer fl guide scope is in order.

Edited by Mkofski (10/28/13 10:55 PM)


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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: ZEQ25 PE Curve new [Re: Astronewb]
      #6163441 - 10/28/13 09:58 PM

Quote:


On the contrary, I think it says it all.




Most mounts will have PHD graph that smooth if guiding with finder. So, no, it does not say all at all.

Of course, that does not mean that resulting image can't be good.


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Falcon-
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: ZEQ25 PE Curve new [Re: orion69]
      #6163788 - 10/29/13 12:33 AM

Quote:

Quote:


On the contrary, I think it says it all.




Most mounts will have PHD graph that smooth if guiding with finder. So, no, it does not say all at all.

Of course, that does not mean that resulting image can't be good.




Actually I would say that most mounts in this price range do NOT necessarily give such good results, even with 50mm finder-guiders.

There is a reason I got my ZEQ25 to replace a CG5....


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Tony Finnerty
member


Reged: 03/06/13

Loc: Nevada City, California
Re: ZEQ25 PE Curve new [Re: Falcon-]
      #6164416 - 10/29/13 11:56 AM

Hey nomosnow, I imagine you get tired of the white stuff up there in Saskatchewan, but we're looking forward to the small amount we get in winter in Nevada City, in the Sierra Nevada foothills! I was shooting M31 at the time, which was located at DEC +41 deg 20'. I'm chasing down a flexure issue, so no image to post. An early version shot with a different lens can be seen here .

Knez, I was guiding with a Lodestar on a Stellarvue 60mm finderscope. My post is a bit off topic in the sense that it doesn't measure periodic error, only what is possible when guiding the ZEQ25. I'm very pleased with what I got for $950 (mount + polar scope + 2" tripod). Until my 4" refractor arrives the mount is carrying only telephoto lenses like a 50-200mm zoom lens + mirrorless camera. Paul has shown us the ZEQ25 can perform with a ridiculous payload compared to its own weight. I bought this mount based on his early results - thank you, Paul!

Paul, you are very correct that this quality of guiding can be achieved with 10 minutes to setup, polar align and one-star align, even in the hands of a total newb in the midst of acquiring his first telescope and mount. The ZEQ25 combined with a 4" refractor will be an awesome mobile AP system.

Mike, Knez and Falcon - the bottom line is the quality of guiding. A very expensive mount can track accurately for long exposures without guiding. A less expensive mount compensates for less expensive mechanicals by way of software (guiding). The key is smooth performance so guiding can be precise. The ZEQ25 mechanicals are smooth enough so guiding is very effective. I never expected to afford performance this good.


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rmollise
Postmaster
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Reged: 07/06/07

Re: ZEQ25 PE Curve new [Re: Falcon-]
      #6164574 - 10/29/13 01:16 PM

Quote:

Actually I would say that most mounts in this price range do NOT necessarily give such good results, even with 50mm finder-guiders.






Which mounts are you speaking of specifically? I've found the VX and the Sirius give results pretty much identical to these.


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