Posted 22 April 2014 - 12:33 PM
A quick one (hopefully) to answer..?!
When NexStar confirms that it is successfully aligned, will it automatically select the appropriate tracking rate to match whatever I wish to view?
Posted 22 April 2014 - 02:06 PM
You don't actually say which 'scope you own, but I think you'll find that the tracking "MODE" is automatically slected according to the procedure by which your Nexstar has been aligned, (i.e. Alt./Az. or EQ North or South), while the tracking "RATE", (i.e. Sidereal, Lunar or Solar), is open to choice depending on what you wish to view; the default setting being Sidereal.
Posted 22 April 2014 - 03:08 PM
Apologies; my scope is a CPC 925. You've both indicated opposite answers regarding the 'tracking rate'! Any elaboration?!?
Posted 22 April 2014 - 03:44 PM
Unless your 'scope is wedge mounted and therefore simply operates in Alt./Az., let's assume you carry out either of the following to align it:-
2) Auto Two Star Align.
3) Two Star Align.
4) One Star Align.
5) Solar System Align.
In these cases and assuming a successful alignment, your 'scope will automatically switch in tracking MODE, from none at all,(i.e. "OFF", prior to alignment) to Alt./Az.
So now it's up and tracking in Alt./Az. MODE but at the default SIDEREAL RATE (speed), which is fine for tracking the stellar background, fixed DSOs etc.
However, if you want to change your object selection to viewing, for example, the Moon, then you can use the LUNAR RATE option (via Menu - Tracking - Rate).
Or again, for planetary or Sun viewing, you might want to choose "SOLAR" RATE.
In practice though, I think you'll find that unless you wish to view the Moon, Sun or planets over much protracted time; to leave the RATE setting on the default, SIDEREAL will be entirely satisfactory.
Does this answer your further question ?
NB. If you're unaware: once you have accessed "TRACKING" from the !"MENU" button: after pressing "ENTER", the "MODE" or "RATE" is selected by toggling either the 6 or 9 buttons on your hand controller.
Posted 22 April 2014 - 03:56 PM
Thanks for clearing this up!
As you guessed, my scope is used in AltAz mode. I can't believe that NexStar doesn't automatically adjust the tracking rate depending on what is observed! Seems an obvious omission to me..?
Posted 22 April 2014 - 04:02 PM
Well I guess as they say, "You can't have everything" (much as we'd like to) !
But joking aside, unless you want to view the Moon, Sun or planets for hours on end, retaining the default sidereal rate will be more than adequate.
Posted 22 April 2014 - 04:57 PM
As far as balance us concern, I used a pencil to locate the balance point. What I need to determine is where to put that point when I put it back on the mount.
As far as backslash adjustment is concern, I think it is an adjustment that needs to be done by trial and error.
But I got annoyed by some minor issues with the Nexstar SE, I decided to upgrade to a Evolution 6! I am just awaiting receipt now. I hope tracking will be easier with the better gears.
Posted 23 April 2014 - 10:01 AM
You are right about the backlash...
BYW...My 8i will keep the ENTIRE full moon within the FOV of the standard 25 mm eyepiece for at least 7 full hours but it is getting close to the edge of the FOV after that amount of time...
Posted 23 April 2014 - 01:35 PM
Since we've drifted onto the subject of balance...
My CPC 925 is front heavy (when viewed from behind) even when I attach Binoviewers. Therefore, I have set the Alt GOTO Approach to 'Positive' (as well as the AZ setting).
Firstly, have I set this adjustment correctly? Secondly, should I be too concerned with countering this with weights when operating only in AltAz?
Posted 26 April 2014 - 02:20 PM
My C8 and C11 are both back end heavy and my GoTO approach is Positive on both axis
Posted 27 April 2014 - 02:33 AM
Very hard for me to believe the CPC 9.25 is front end heavy ...
Bob, I just walked over to a Fastar ready CPC925 and with the finder, VB, prism, a Meade 5000 SWA 24mm EP, and no dew shield, it is is slightly front end heavy.
Posted 27 April 2014 - 11:03 AM
My question(s) posted earlier (23 Apr) still remain extant - any thoughts? Most grateful!
Posted 27 April 2014 - 12:09 PM
In the choice between which Altitude GoTo Approach to adopt, I have always gone along with Mike Swanson's advice contained in his book, "The Nexstar User's" Guide". Not that I follow his words blindly and in some respects I disagree, as he knows, with his opinions.
However, and bearing in mind that at the time he wrote this excellent but now outdated book, he advocated setting the 8 and 11CPS to Positive, likewise the then Nexstar 8i, to take advantage of, as he described, the natural backend heaviness of these 'scopes. I therefore set my then "fixed to the arm" Nexstar 8i accordingly, i.e. Alt. GoTo Approach: Pos. / Az. GoTo Approach: Pos. Note though, that the 9.25" model was not around at the time.
But models and times change and despite Mike writing his book in the closest co-operation with Celestron, the later two Nexstars to come along, i.e. the 6SE and 8SE were factory set by default to a Negative Altitude GoTo Approach: presumably under the assumption that these 'scopes would in future be normally a little front end heavily set in the dovetail to permit Zenith access, a feature the old "fixed to the arm" Nexstar 8i never enjoyed.
Again, with this in mind that, if as you say, the 9.25 CPC is fore-end heavy, I would be inclined to set a Negative rather than a Positive GoTo Approach. I would also suggest though, that experimenting with both Negative and Positive settings would do no harm in establishing which you personally find the better of the two. In other words, I don't think there is any hard and fast rule attached to this.
Goto Approach selection however, is very important in determining the directions from which alignment stars and objects are best centred in the EP where spur geared Nexstar models are concerned but I think not in the case with worm drives such as the 9.25CPS sports, as backlash has far less a significant influence.
Regarding adding weight to counterbalance, unless the imbalance is high, I think the worm drive is robust enough to take it and indeed probably use it to small advantage as a gear preload.