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Alt/Az ratios for the StarNavigator NG

Meade
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#1 FedericoB

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Posted 30 November 2020 - 08:00 AM

Hello everyone,

 

Recently I found the arm mount of the StarNavigator NG series for very cheap even though it works perfectly. 

It seems to have originally come with a 5 inch Maksutov Cassegrain.

 

In order to use it I managed to also get for cheap a used Autostar #497, which I managed to upgrade to the latest 43G version.

This particular Autostar controller seems to have been paired with the original small ETX and DS series of the early 2000s, (i.e DS2XXX, DSX125, etc).

As far as I know, the StarNavigator NG series came with the Audiostar and not the Autostar, so default values for various parameters may not be the same across controller firmwares.

 

My question is whether the Alt/Az ratios that the controller displays by default match those of the StarNavigator NG series?

 

The current values are as follow:

Alt/Dec ratio: + 01.155000

Az/RA ratio: + 00.840568

 

 

If anyone out there has a StarNavigator NG series scope I would really appreciate it if you could check the default ratios, I would like to make sure they match the above values, or if they don't I can update them.

 

I haven't had a chance to take it out yet because of bad weather/scheduling, but when I point it at certain objects while I am inside the house, it seems to be 'slightly' off with respect to phone apps like Stellarium, and me going out the balcony. 

 

I tried searching online but only found one obscure post mentioning that the StarNavigator NG series has ratios that match those of the large ETX line (ETX90/105/125), but the number the forum member gave did not have as many digits as the above, so decided against trusting it.

 

Thanks for reading.



#2 Piet Le Roux

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Posted 30 November 2020 - 11:39 AM

Good day, 

I am not sure what the gear ratios should be for the starNavigator NG but under setup, model what model did you select? You can test the values of the ETX scopes by selecting one and placing the OTA level and adjusting your Ra and Alt dials to zero, reboot and when the scope has booted keep pressing "MODE" until it displays "select Item: Object" then press and hold "MODE" for 3 seconds, it will display your RA and Dec counters, press the down scroll arrow and it will display your Alt and Az counters, they should all be zero. If you then press the left slew button and let it turn for let say 90 degrees (6 hours Ra) on the RA dial, the your Az counter should have changed by + or - 90 degrees. The same can be done on the Alt control move 90 degrees and compare the dial with the electronic counter, if they corollate your gear ratios for the two drives are correct, the rest does not matter.   


Edited by Piet Le Roux, 30 November 2020 - 11:43 AM.

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#3 OzAndrewJ

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Posted 30 November 2020 - 02:43 PM

Gday Federico

 

The StarNavigators are basically rebadged DS-2xxx mounts so your numbers are OK

ie +0.8405671 and  +1.1550000

 

The 497 actually works with all the Meade mounts  incl the LX90

but what gets presented to you for selection is only a small subset

based on the detected motor card in the attached scope.

Other than the ratios, the only things that get set by the different models

is the upper and lower slew limits and the focal length ( for spiral search box sizing )

 

Andrew Johansen Melbourne Australia


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#4 FedericoB

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Posted 30 November 2020 - 05:53 PM

Hello Piet Le Roux and OzAndrewJ,

 

Thank you very much for both of your advice.

 

I was able to indeed verify that moving 90 degrees in either altitude or azimuth would be corroborated by the Alt/Az numbers shown in the controller. This is such a good trick... 

 

Andrew, thanks for your comment, I was wondering how the Autostar was able to detect which type of mount I had since I knew these controllers sold with even the LX90 lineup.

With regards to your comment about focal length, so if I change the focal length on the telescope model section I will also alter the spiral pattern?
I'm paring up this mount with a Meade 2045D, which as a focal length of 1000mm.

 

 

Thanks again for both of your comments.



#5 OzAndrewJ

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Posted 30 November 2020 - 06:07 PM

Gday Federico

 

so if I change the focal length on the telescope model section I will also alter the spiral pattern?

Correct. That is pretty much all the focal length is used for "operationally" .

 

( It is also used in the "calculate FOV" menu for listed Meade eyepieces

but that is info only, it doesnt get used anywhere)

 

Andrew Johansen Melbourne Australia


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