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Equipment Discussions >> Mounts

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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: LX80 RA Tracking new [Re: neilson]
      #5364195 - 08/12/12 01:29 AM

Gday Neilson

Quote:

I do have one question, every time I try an indoor dummy alignment, I set it up with no ota or weights, leveled. Then I do the "easy" alignment using times of 9 or 10pm at night. It slews to the stars and I press enter but it gives me numbers of 7' and 8' off the pole or 8' and 9' off the pole. I might have to redo it 2 or 3 times before I get "less than 5'from the pole. Shouldn't I always get less than 5' from the pole?




You are seeing the effects of lots of maths using sine/cosine/tan etc
done by a processor that isnt designed to do floating point calculations.
Also, a lot of Meades code doesnt know about rounding to the nearest number,
it nearly always truncates.
As such, some of these more complicated calculations ( that also involve time )
dont come out perfectly. It also happens on the LX200s at times.
Just do a polar one star align after drifting etc, and dont worry about it.

Andrew


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neilson
professor emeritus


Reged: 08/22/10

Re: LX80 RA Tracking new [Re: OzAndrewJ]
      #5364360 - 08/12/12 07:14 AM

Andrew
Thank you, It just had me wondering if it was effecting my real polar alignments. I'm glad its nothing. That's one less thing I have to worry about now.
neilson


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: neilson]
      #5364469 - 08/12/12 09:37 AM Attachment (13 downloads)

Neilson

One thing you can do to test your polar alignment is to point at Meridian and 0 and select target then turn target to terrestrial this will turn off drive motors and the sky will drift across the you camera take about 6 or 7 min exposure I let the mount set for about 5mins then turn the mount back to astronomical then 8x sidereal rate and catch up to the star if you don't catch the star that's ok you are looking at a long star trail due to earths rotation and the second is your mount polar alignment trail you want both to be on top of each other if not your alignment is off. because we use PHD to align I was wondering if the graphic was lying to me.We are using new Ver. of software than what we are using on LX55 so it was away to confirm what PHD was telling me about the alignment was true or not!

hope this helps


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5364480 - 08/12/12 09:47 AM Attachment (18 downloads)

This is the PHD graph on the drift alignment the above photo was to confirm that what the graph was showing is true.

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neilson
professor emeritus


Reged: 08/22/10

Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5364579 - 08/12/12 11:26 AM

Hi Kevin
Thanks, I'm going to give that a try. It makes perfect sense.
neilson


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ur7x
professor emeritus


Reged: 01/08/12

Re: LX80 RA Tracking new [Re: Starhawk]
      #5366135 - 08/13/12 10:22 AM

Quote:

I'm kind of exhausted on this. The mount would make a lot more sense to me if it was coming from some company new to making mounts. But our newbies like iOptron have been kicking a-- compared to what's been seen, here.

I saw the note from Meade. It's better late than never, I suppose. It's pretty clear they never took a first article and tried it out. The software fix won't help burrs on gears, so hope that isn't an element of this problem.

I'm seriously wondering what will happen for other people getting an LX80. Celestron had a history with the CGEM where some would have things like runaways because of faulty encoders and such, but if the mounts weren't actually broken, they did work. It was clear someone had wrung out the design details, even if there were teething manufacturing issues to track down. This business where the LX80 as originally delivered could not possibly have worked if Meade had done even the most cursory checkout of a prototype is quite disheartening, and as follow-on issues have presented themselves, has become more so. With the amount of gear they have in service, they should know better than anyone how to get this sort of equipment right on the first try. It's pretty obvious they didn't try.

I know I'll have people standing in line to tell me how unfair I am for saying this, and may see this get deleted, anyway. I have a family to look after- in the long run it's better for me to put my energy there, and let others worry about the ethics of major vendors claiming performance they haven't verified then crowd-sourcing checkouts on $1000+ pieces of equipment.

I feel helping them out this way is enabling a really bad practice to continue.

I didn't post this to entertain people or just to be contrary. I don't expect everyone agree with much of what I've said here. I would like to have a path forward, though.

-Rich




I agree with all of this, but I think the bigger issue is Meade's apparent attitude (and complete lack of support or interest) towards Nelson's questions, issues, and calls for assistance.

I came within a heart beat of ordering one of these mounts too. I left this hobby a couple of decades ago, mostly due to a telescope that I bought that had outstanding optics, but a mount that could barely hold itself up. In years gone by the mantra was always "aperture, aperture, aperture". I have now discovered that if you actually want to have ANY success in this hobby, the mantra should be "mount, mount, mount".

Part of me wants to applaud the effort that some of the faithful are putting in to this mount; but mostly I wonder, "Wow, if I had just sunk $800-$1000 into a mount and had this number of challenges would I be returning it.", and likely mothballing my OTA (for another 20 years).

Thanks to all, some honestly, some sarcastically, who help steer me away from this mount.


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: neilson]
      #5366406 - 08/13/12 12:50 PM Attachment (32 downloads)

I took seven photos starting at 60 sec , 90 sec, 150 sec, 300 sec, 400 sec, 600 sec, and 781 sec. So starting a 1 min up to 13 min. all photos are unguided taken with Canon 3ti all frame 300 sec and above the background was darken this is why the background doesn't look the same on longer frames. This was done due to the bad Sky glow. Pixel size 4.3um Array size 5184 x 3456 with 72mm f6 430FL Arc sec per pixel 2.60 each photo had a 5 sec delay between photos camera controlled remotely. In the photos you will see a line of stars at 400% on the left this is the same star in each photo the star chosen is indicated by a white arrow in the top of the frame. The test took a little over 45min. to do. The good news the mount from start to finish kept Vega in the center of the FOV. You can see in the stars as short as 60 sec this back and forth motion in RA you do see a little movement in dec look at the stars some are more downward motion than others. this was done the same night as the drift graphs shown above. so polar alignment was very good. winds lite from the north 5 mph setup had wind protection on two sides north and west.

Edited by TALK2KEV (08/13/12 01:02 PM)


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5366416 - 08/13/12 12:56 PM Attachment (24 downloads)

150 sec unguided frame

Edited by TALK2KEV (08/13/12 12:58 PM)


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5366419 - 08/13/12 12:58 PM Attachment (21 downloads)

300 sec frame

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rmollise
Postmaster
*****

Reged: 07/06/07

Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5366555 - 08/13/12 02:09 PM

Your "back and forth" looks exactly like what I would expect periodic-error wise in an unguided mount in this class.

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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: rmollise]
      #5366606 - 08/13/12 02:43 PM

What I was concerned with is the fact that it showed up so quickly 60 sec even less the good thing It doesn't seem to move more over a longer period of time I believe the size difference is just saturation. If Meade gets the PEC working I hope this will solve my issue.

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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5366631 - 08/13/12 02:57 PM

If we used a longer FL on the guider this should see errors quicker and maybe it would guide out better? just a thought would like your epinion, what Guide scope do you use?

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neilson
professor emeritus


Reged: 08/22/10

Re: LX80 RA Tracking new [Re: TALK2KEV]
      #5366747 - 08/13/12 03:50 PM

Kevin,
I see what your talking about. I wouldn't expect that much at 60sec. with the fl 430mm with a big 18mp imaging chip and you don't have much weight on the mount. But at 781 sec. it doesn't seem much worse. At first mine had alot of play in RA, you could move it back and forth 1/4" but I fixed that. But it showed up much worse than what you have.
Could it possibly be from the balance of the ota in the dovetail receiver, after you attached your camera the ota becomes heavier in the back. The reason I say that is I noticed my mount is very sensitive to being the slightest off balance. Although my refractor weights more and when adding my camera it's farther from the mount making it off balance easier. But it was just a thought.
I am using 988mm fl and a 15.1MP imaging chip and with just a regular polar alignment "less than 5' from the pole" My stars are round up to 80sec unguided image magnify to 400% on anteres and arcturus and the cats eye nebula. I didnt try vega though. but at 90sec I start getting small trails when I magnify to 400%
neilson


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: LX80 RA Tracking new [Re: neilson]
      #5367009 - 08/13/12 05:57 PM

Gday Kevin/Neilson

Quote:

I see what your talking about. I wouldn't expect that much at 60sec.




You really need to know where in the PE model you are, to see how quick things change "at that point".
Ie if you imagine the PEC is a pure sine wave ( just for the initial analogy )
If you did a 60sec image starting 30sec before the peak and going 30sec past,
you dont move very far in RA relative to target.
If you started imaging 30sec before it crosses zero and stopped 30sec after,
you will get the maximum amount of movement in RA in a given time.
Ie the "rate of change" is whats important, not the total error.
Thats why +/-50arcsec of "very smoothly changing" PE is better than +/-10arcsec of PE that looks like a sawblade.

Andrew


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jmiele
Patron Saint?
*****

Reged: 12/04/10

Re: LX80 RA Tracking new [Re: OzAndrewJ]
      #5367040 - 08/13/12 06:25 PM

Yes, but what's the spec on this mount? They don't list it. They don't list the PE. They do say it has PEC in Polar Mode. Curious as it doesn't work nor has it from inception. And as guiding haven't been proven to work yet, even a smooth PE means absolutely nothing.

Joe


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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: LX80 RA Tracking new [Re: OzAndrewJ]
      #5367058 - 08/13/12 06:35 PM

Andrew,
You are exactly right. The second derivative is what is important. If the mount can be guided these results are actually good. The total PE does not look all that bad.


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: LX80 RA Tracking new [Re: OzAndrewJ]
      #5367087 - 08/13/12 06:49 PM

Quote:

Also, a lot of Meades code doesnt know about rounding to the nearest number,
it nearly always truncates.



Meade developers “round” numbers the way they were taught at school. Did you notice that Excel always truncates numbers?


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: LX80 RA Tracking new [Re: jmiele]
      #5367090 - 08/13/12 06:51 PM

Gday Joe

Quote:

Yes, but what's the spec on this mount?




No idea

Quote:

They do say it has PEC in Polar Mode. Curious as it doesn't work nor has it from inception.




Correct, ( for the new handboxes ). The std 497 always worked OK.
When patched, the new firmwares do appear to work as advertised.
The new bugs are simple errors associated with the porting of the code between processors, not the basic process itself.
The patched firmware has been used successfully by LX90 users for the last few years as well, so when it works, it does appear to work.
I agree it shouldnt need patching, but up till now, thats been the only way to actually get the mount to work ( for those who wanted to use PEC ).
I reckon it partly because 99% of users of the Audiostar never use PEC so i guess its never been important till now.


Andrew


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: LX80 RA Tracking [Re: jmiele]
      #5367123 - 08/13/12 07:07 PM

Neilson
Thats great you can go 80sec and not see the error with that long of FL.
It could be unbalance in OTA but if so not much when I balance for the night I put the camera and set up the way it will be when I use it then I take out the camera which was the DSI pro and use Diagonal and Ep in to start my polar alignment then I put the DSI pro back in to finish my polar alignment using PHD and the grid to finish up. But I didn't re balance for the Canon 3ti which is heavier than the DSI pro.

Andrew
so if I put a 6" f11 Mac as main OTA and shoot through it the longer FL should show my PE larger in the photo I'll try and set up to do test with that if I can get a dove tail mounted up to the 6" or use the 72mm and shoot through a 2" barlow would give me a 860 fl if i can get focus.


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: LX80 RA Tracking [Re: Alph]
      #5367125 - 08/13/12 07:07 PM

Gday Alph

Quote:

Did you notice that Excel always truncates numbers?





Nope. I try to keep viruses off my PCs

However, if anyone wants to see the effect in action
start yr handbox up and go to the ratio screen.
Now hit enter to put it into edit mode and hit enter without changing anything. Keep repeating, and watch what happens to the last digit
This isnt so critical when its the 5th or 6th decimal, but when doing PEC, which only works in small integer steps, having 0.999 round down to zero can have larger effects.

Andrew


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