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Peter in Reno
super member
Reged: 07/15/08
Posts: 117
Loc: Reno, NV
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I am disappointed in a $1500 Atlas EQ-G mount that does not allow enough azimuth movement for easier polar alignment. Yeah, I know you can do rough alignment but you may have to rotate the tripod which will affect leveling and Atlas mounts are quite heavy. I know leveling does not have to be precise but for a $1500 mount, why didn't they include flexibility to easily polar align?
Anyway, does anyone make some kind of rotatable plate or adapter to fit in between the tripod and Atlas EQ-G mount so the mount can be easily rotated a lot more (at least 30 degrees) than the stock Atlas EQ-G?
What about Losmandy G11 mounts? Do they rotate more than Atlas EQ-G? I don't want to buy Losmandy because it cost too much for my needs. Edit: From Losmandy web site, azimuth adjustments is ± 8.5°. How much does Atlas EQ-G rotate?
FYI, I do not yet own a telescope or mount but I have been eyeing on Orion's Atlas with Celestron 11 OTA. Orion Atlas C-11 is backordered until September 1 (hopefully it will not be delayed further like their StarShoot Pro CCD).
Edit: Basically I want to set up the telescope/mount during the day so that I am ready for polar alignment while it's dark and I don't want to rotate the whole tripod/mount/telescope which weighs total of 115 lbs if the rough initial daytime set up didn't quite line up to the Polaris.
Thanks,
Peter
Edited by Peter in Reno (07/19/08 08:32 PM)
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Grouptele
super member
Reged: 08/11/07
Posts: 142
Loc: Qcy, IL
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All the equatorial-type mounts I know (EQ-G, ASGT, SXW) have precise but limited azth adjustment range. I believe it is typical of the GEM mounts. I do not know of a commercially available spacer to allow large azth adjustments.
If your set-up is a home yard (like mine), polar align the mount (alone) one night and mark the spots on the ground. Then place 3, flat landscaping stones or bricks on the marked spots. Now the next time you set up the mount, you'll be closer to polar alignment position - at least within the azth adjustment range of the mount.
Victor.
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C8-XLT, G5, AT66
EQ-G
Starshoot color CCD
SPC900NC webcam
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Charlie Hein
Postmaster
Reged: 11/02/03
Posts: 6429
Loc: 26.06.08N, +80.23.08W
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Peter,
How do you currently estimate where to place your tripod during the day? If you're just guessing then you're almost always going to be way out unless you visit the site frequently and can use landmarks to help - and even so you'll often be out further than most GEM's are capable of compensating for. Most can't adjust much further than the Atlas can. You really do need to do better than a guesstimate on this...
Even if you use a compass but do not correct the magnetic declination from true north you're still going to be a good way off from true north depending on where you live. For example, the magnetic declination from the center of zip code 89501 in Reno is 14° 29' east of true north. That's likely to be further than the Atlas can compensate for if you don't take declination into account.
IMO, the best way to estimate where to place your tripod during ther day is to use a compass that can be adjusted for magnetic declination to determine the location of true north. You can pick one up that will work perfectly for this application for under $20.00 (although it's easy to spend a lot more if you wanted to).
It's important to know the coordinates or at least the zip code of the location where you're going to be observing from before you head out. With this information you can use the NGDC's Magnetic declination estimator to add in the magnetic declination on your compass before you even head out.
Then - when you get to the site you just point your compass to North, line up your tripod along that line and set the altitude on the mount to where your latitude is. The chances are very good that Polaris will be in your polar finder scope right off as soon as it gets dark. At the worst, it'll be well within the range of your mount's altitude and azimuth adjustments.
Charlie
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Weston CSC:
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RAKing
professor emeritus
Reged: 12/28/07
Posts: 714
Loc: Virginia
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Quote:
What about Losmandy G11 mounts? Do they rotate more than Atlas EQ-G? I don't want to buy Losmandy because it cost too much for my needs. Edit: From Losmandy web site, azimuth adjustments is ± 8.5°. How much does Atlas EQ-G rotate?
The Atlas gives you about the same. All the GEMS I'm familiar with give you about 15 degrees total azimuth adjustment. We have to be able to lock the azimuth axis down against that alignment pin, so our mounts will hold alignment and track properly. The diameter of the base and the geometry of the azimuth bolts sets the limit. The azimuth pin for the Atlas is 45mm from the centerline of the mount.
There are two things you can try: 1) Simply unscrew the alignment pin and depend on friction to hold the mount in place. Or 2), Try the Atlas 8-inch extension. It works the same way. It does not have an azimuth pin and depends on friction as well.
To be honest, most of us just get used to shifting the tripod.
Take care,
Ron
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Time spent looking at the stars is added to your life.
"Hi Def" TV-102
I-M M703 MCT
C925-CF SCT "Time Machine II"
GM-8 GEM / A-P Portable Pier
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Peter in Reno
super member
Reged: 07/15/08
Posts: 117
Loc: Reno, NV
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Take a look at the attached 30 year old picture of my Celestron 8 I owned for 5 years when I was a teenager. My father and I found it ridiculous to rotate the tripod for polar alignment so my father designed and built a neat tool to fit in between the wedge and tripod as shown in the attached photograph. This tool also rotates the wedge 360 degrees! No matter how unleveled the tripod is, this tool can easily compensate and level the wedge. Also I had aftermarket lattitude adjuster which is not shown in the picture.
30 years later, nobody makes anything like this and we still have to rotate the #$%&@ tripod!!!!!
I can live with minimal azimuth adjustment of today's GEM so I am not complaining (ok, a little bit). 
Peter
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Celestron 11" OTA
Orion EON 80mm
StarShoot Pro
StarShoot Auto Guider
Nagler 31mm
Ethos 13mm and 8 mm
2" William Optics diagonal
Atlas EQ-G
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Peter in Reno
super member
Reged: 07/15/08
Posts: 117
Loc: Reno, NV
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More pictures. I don't know how to post multiple pictures in single post.
Peter
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Celestron 11" OTA
Orion EON 80mm
StarShoot Pro
StarShoot Auto Guider
Nagler 31mm
Ethos 13mm and 8 mm
2" William Optics diagonal
Atlas EQ-G
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Peter in Reno
super member
Reged: 07/15/08
Posts: 117
Loc: Reno, NV
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Another picture.
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Celestron 11" OTA
Orion EON 80mm
StarShoot Pro
StarShoot Auto Guider
Nagler 31mm
Ethos 13mm and 8 mm
2" William Optics diagonal
Atlas EQ-G
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