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C11 NexStar alignment always a bit "to the left"?

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#1 Kevdog

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Posted 03 January 2013 - 03:04 AM

I recently got a used C11 NexStar (carbon fiber tube).

I do a careful alignment, using a 7mm eyepiece to center each star. When I set an object to slew to in the handset, the scope always stops with the object "off to the left" of the eyepiece every time and it seems by about the same amount.

Is there something I can do to fix that? Any adjustments?

Do I have to have my tripod exactly level? My driveway slopes and I adjust the tripod to get it mostly level, but it varies a bit depending on where I set it.

Anything else I should check?

Thanks!

#2 cn register 5

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Posted 03 January 2013 - 05:46 AM

What versions of HC and MC firmware are you using? (Menu - Utilities - Version).

Do you have an estimate of the amount it's out? A 7mm EP will give a magnification of x400 and that gives a field of about 7.5 arc minutes. An offset of a couple of arc minutes will be very obvious but is the sort of positioning accuracy that can realistically be achieved.

Levelling the mount should make no difference, the two star alignment will make up for this as long as it's about right.

Chris

#3 snowcrow

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Posted 03 January 2013 - 06:20 AM

Try adjusting the "Backlash" on the drive. That is what it sounds like it needs. ANd yes, your scope needs to be perfectly level!

#4 Kevdog

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Posted 03 January 2013 - 10:26 AM

I'll have to check on the firmware versions. No idea, but they might need an update!

Yes, I'm using a 52deg FOV 32mm eyepiece. Both Jupiter and the Orion Nebula were just outside the field of view of the 32mm eyepiece, and that seems to be consistent every time I set it up.

I'll look into the backlash setting. Thanks!

#5 mclewis1

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Posted 03 January 2013 - 03:12 PM

The vast majority of NexStar GPS scopes came with pre v4 hand controllers and therefore cannot be upgraded short of replacing the hand controller.

The motor controller firmware can be upgraded using the PC port and appropriate cable.

#6 Kevdog

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Posted 04 January 2013 - 04:01 AM

So if I don't have a version menu item under utilities, then I'm assuming I have an older hand controller!?!

What does the newer controller give you over the older one? Looks like they run $140. What would make it worth upgrading (if anything)?

#7 snowcrow

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Posted 04 January 2013 - 04:57 AM

Try Menu> Scope Setup> Anti-Backlash, if that is the menu item you are looking for.

#8 cn register 5

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Posted 04 January 2013 - 06:20 AM

The version option has been present in the Utilities menu since version 1.6, I'm not sure about earlier, but Mike Swanson's Nexstar site may be able to help, there were some that didn't have the Version option but they were early in the NexStar GPS life.

Chris
Chris

#9 rmollise

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Posted 04 January 2013 - 11:44 AM

Try this. Do final centering of the alignment stars using the up and right keys only. If backlash is a problem, that will take care of it. ;)

#10 Kevdog

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Posted 04 January 2013 - 01:35 PM

The version option has been present in the Utilities menu since version 1.6, I'm not sure about earlier, but Mike Swanson's Nexstar site may be able to help, there were some that didn't have the Version option but they were early in the NexStar GPS life.

Chris
Chris


Thanks for the site info.... very helpful!

So, it looks like I have the original 1.2 Hand Control, which means I probably have the MC version 1.0. To update the hand controller I'd also have to replace the MC board! Argh.

So looks like I'm at a dead end with upgrades, or I spend $300+ to get things "up to date"!

Is there anyone in AZ who does a "supercharge" like service for Celestrons? I don't want to ship it. But maybe could get the board and HC updated and get everything else tuned all at once?

#11 junomike

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Posted 04 January 2013 - 01:53 PM

Kevdog, I`d give you NS11GPS a few more outings first just to be sure an upgrade is needed. I have the same scope and It came with HC V2.2, but I see no real difference between It and your version. My HC V2.2 performs as accurately as my HC V4.16. The newer HC looses the GPS Align but gains Sky Align. I use neither and prefer a 2-Star Alignment.

If you`re handy and not to nervous there is a fellow who can upgrade the MC. See Here!

Mike

#12 rmollise

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Posted 04 January 2013 - 01:57 PM

The version option has been present in the Utilities menu since version 1.6, I'm not sure about earlier, but Mike Swanson's Nexstar site may be able to help, there were some that didn't have the Version option but they were early in the NexStar GPS life.

Chris
Chris


Thanks for the site info.... very helpful!

So, it looks like I have the original 1.2 Hand Control, which means I probably have the MC version 1.0. To update the hand controller I'd also have to replace the MC board! Argh.

So looks like I'm at a dead end with upgrades, or I spend $300+ to get things "up to date"!

Is there anyone in AZ who does a "supercharge" like service for Celestrons? I don't want to ship it. But maybe could get the board and HC updated and get everything else tuned all at once?


You don't need a supercharge. You need to try the up and right process like I mentioned. Upgrading will not help your problem anyway. I've been through all the versions and none of them did anything to affect go-to accuracy. All the latest versions will do is remove your GPS north-level alignment and replace it with the alignment methods used in the newer CPCs.

#13 Kevdog

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Posted 04 January 2013 - 03:48 PM

I think I do the up and right process each time, but I'll have to verify that again. I remember reading it when I read through the manual and always try and remember to do that for the final align.

But I'll do another align and double check that and see if my accuracy is better. I'll also make sure the tripod is (mostly) level. My driveway is all graded, with none of it constant. If the scope wasn't quite as heavy, I'd haul it around to my pool patio (pool is filled in and now has fake grass on it) as that's my only level spot on the property. I used to carry my LT8 around there and it was nice, but the C11 is a little bit heavier :D

Thanks for alleviating my worries about the older firmware/HC/MC. I assume I can still hook up to a computer just fine whenever I finally buy a connector cable? I don't want to do any serious AP, but I do have a wedge and would like to dabble some more.

If I can get the alignments much more consistent and accurate, then I'll be happy. Would like an illuminated reticle eyepiece too, but I'm sure that's not necessary, just nice :D

I was thinking about a "supercharge" just to ensure everything is working as good as it can (as I know it's an older scope) and I'm still enough in the learning stage to not know for sure if something is right or not!

#14 MikeBOKC

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Posted 04 January 2013 - 07:00 PM

Kevdog, in the absence of a reticle eyepiece you can defocus the alignment star until it nearly fills the field of view and easily get a precise centering that way.

#15 rmollise

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Posted 06 January 2013 - 07:13 PM

I think I do the up and right process each time, but I'll have to verify that again. I remember reading it when I read through the manual and always try and remember to do that for the final align.

But I'll do another align and double check that and see if my accuracy is better. I'll also make sure the tripod is (mostly) level. My driveway is all graded, with none of it constant. If the scope wasn't quite as heavy, I'd haul it around to my pool patio (pool is filled in and now has fake grass on it) as that's my only level spot on the property. I used to carry my LT8 around there and it was nice, but the C11 is a little bit heavier :D

Thanks for alleviating my worries about the older firmware/HC/MC. I assume I can still hook up to a computer just fine whenever I finally buy a connector cable? I don't want to do any serious AP, but I do have a wedge and would like to dabble some more.

If I can get the alignments much more consistent and accurate, then I'll be happy. Would like an illuminated reticle eyepiece too, but I'm sure that's not necessary, just nice :D

I was thinking about a "supercharge" just to ensure everything is working as good as it can (as I know it's an older scope) and I'm still enough in the learning stage to not know for sure if something is right or not!


In additon to up and right, make sure you are using a reticle eyepiece, as I believe somebody else mentioned. 12mm is a good alignment eyepiece f/l. Leveling will not do pea-turkey to improve alignment quality, though it can make the two initial alignment stars fall closer to the center of the finder. ;)

#16 Kevdog

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Posted 08 January 2013 - 06:11 PM

Kevdog, in the absence of a reticle eyepiece you can defocus the alignment star until it nearly fills the field of view and easily get a precise centering that way.


That is a good tip! Will have to try that.

I'm using a 7mm eyepiece, so should be quite easy.

#17 Cellofan

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Posted 10 January 2013 - 06:53 PM

In additon to up and right, make sure you are using a reticle eyepiece, as I believe somebody else mentioned. 12mm is a good alignment eyepiece f/l. Leveling will not do pea-turkey to improve alignment quality, though it can make the two initial alignment stars fall closer to the center of the finder. ;)


I think it's a matter of leveling and is easily controlled with the program PoleAlignMax.

#18 Kevdog

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Posted 13 January 2013 - 05:17 AM

Nice, cold and clear night so I got the scope out and had a good run at it.

Aligned using only up and right.
Defocused the star to help with more precise centering (worked well, but a reticle eyepiece will be better)

I think I blew my 2nd alignment star because it was worse than ever. So chose Aldeberaan to replace it with and alignment was much closer than before. Later replaced Sirius with Procyon and alignment got even closer.

So using only up and right and also being more careful on alignment made a big difference.

Also, after viewing for a while decided to play with my backlash settings. Turns out they were all set at 0. Setting them to 30 seemed to work pretty well. Was getting cold so that was "good enough" for tonight.

Overall was pretty confident in the goto tonight and found many more objects to see. Thanks for all the help. I'm much happier with the goto now and now I can get it even better.

Also, took some time to get the collimation much closer, but Jupiter still wasn't sharp. But by the time I had the collimation good it was already setting :( Will have to have another look, hopefully tomorrow night, but earlier in the night.

Getting precise focus is hard with the stock focuser. Wondering about a Zhumell Crayford focuser for the fine focus?

The scope is really back heavy before I even put any eyepieces on. Could use some weight up front to balance it better. With my Williams Optic 7-22 Zoom or ES82 8.8mm eyepiece on there it almost becomes a catapult!

Got a list of accessories I want now, but hoping to sell my LT8 before I ask the wife for more toys!

Zhumell focuser
Reticle Eyepiece
Flip mirror (for imaging and viewing)
Weight Kit

#19 herrindude

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Posted 13 January 2013 - 12:34 PM

They sell a balance bar that mounts on the bottom of scope and that helped my go to's the most. I upgraded the motor control and lost level north, and have regretted it ever since. So think long before doing, because you cant go back.

#20 snowcrow

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Posted 13 January 2013 - 10:04 PM

Glad to hear you've got the beast pointing proper now. :grin:

#21 rmollise

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Posted 14 January 2013 - 07:53 AM

I think it's a matter of leveling and is easily controlled with the program PoleAlignMax.


Well...sorta...but...not really. ;)

Leveling will help the scope come closer to the initial alignment stars, but that is it; it will have NO effect on the quality of the final alignment.

#22 Kevdog

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Posted 14 January 2013 - 01:38 PM

Yeah, there is no level spot on my driveway (and some very far off) but now that I have the alignment more exact and the backlash adjusted I'm pretty darn close. It's now always in my 32mm eyepiece and just a bit off to the side (which I think I can get even better).

The scope wasn't level but the goto was quite good :D

#23 Sorny

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Posted 16 January 2013 - 10:23 PM

My CPC1100 was back heavy until I put a full starizona counterweight kit on it. I need the big top weight with the dew shield (I don't use the stock finder, I'm using the el-cheapo celestron red-dot).

My alignments and go-tos, for whatever reason, got a LOT better after I balanced the scope and started paying attention to leveling it. I don't have anyplace that is level, but that's why tripods have adjustable legs... I'm thinking things will be easier with my reticle eyepiece, but I've got had first light on the reticle eyepiece yet.






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