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Equipment Discussions >> Mounts

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Jon_Doh
scholastic sledgehammer


Reged: 09/16/11

Loc: On a receiver's back
AVX Latitude Scale Question
      #6074942 - 09/11/13 11:56 AM

I've purchased the new Celestron Advanced VX mount and have a question about the latitude scale. For doing a two star alignment and not polar do I still need to set the latitude for where I am? This may sound stupid to those who use Equatorial mounts, but this is my first experience with one. I come from a fork mounted system and have no experience here.

If anybody could help me with this I would be grateful.


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schluterdude
super member


Reged: 08/05/13

Loc: Centerville, OH
Re: AVX Latitude Scale Question new [Re: Jon_Doh]
      #6075066 - 09/11/13 01:07 PM

Yup, still set it for your latitude. An eyeball polar align is all I usually do, only takes a minute...

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Jon_Doh
scholastic sledgehammer


Reged: 09/16/11

Loc: On a receiver's back
Re: AVX Latitude Scale Question new [Re: schluterdude]
      #6075225 - 09/11/13 02:25 PM

Thanks. This is a totally different form of alignment than what I'm used to. Now if the clouds will ever leave I'll take this thing out and see if I can get it to align.

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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: AVX Latitude Scale Question new [Re: Jon_Doh]
      #6076379 - 09/12/13 05:56 AM

Yeah basically, it's best to set the latitude always... (you will probably know this routine already, but for the benefit of newbies, it's worth a mention):-

If the sky is cloudy and you can't see polaris, this is what I do..

Point the north leg of the tripod, roughly north, I have a magnetic compass for that.

I also have a Skysync GPS to get the date-time-location perfect.

The tripod does not have an inbuilt bubble level, but my compass has one also.. so I level the tripod with that.

Then I add the mount to the tripod, and set the Latitude.

Do a 2 star alignment and upto 4 calibration stars.

Do the All star polar alignment routine, and use the mount's Alt and AZ adjustment knobs to phsyically centre the scope on the ASPA star.

Switch the mount off, Reset the RA and DEC back to the markers, switch the mount on and do the 2 star and 4 calib star alignment routine, then do the ASPA again to check how accurate it is. If you have to make minor adjustments again, then repeat this step.. until it is perfect.

Using a 12mm Eyepiece is ideal for centering the star. Even better is an illuminated reticle eyepiece.

Edited by MartinTreadgold (09/12/13 05:59 AM)


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Jon_Doh
scholastic sledgehammer


Reged: 09/16/11

Loc: On a receiver's back
Re: AVX Latitude Scale Question new [Re: MartinTreadgold]
      #6078391 - 09/13/13 09:22 AM

Thanks Martin. I'll try your method the first clear night I get.

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SkipW
sage


Reged: 02/03/11

Loc: Oklahoma, USA
Re: AVX Latitude Scale Question new [Re: Jon_Doh]
      #6079574 - 09/13/13 11:00 PM

Martin's procedure is very thorough, but far more elaborate than most people will need for general visual use.

I'd suggest following it as far as
Quote:

Do a 2 star alignment and upto 4 calibration stars.



After that, just start observing.

If the star alignment and calibration were accurate, it will slew to targets anywhere in the sky well even if the polar alignment is off (maybe even wildly off, but I haven't tried that yet. Hmmm...) If it's not finding targets accurately, switch it off and repeat the alignment and calibration. Don't try ASPA if GoTos aren't good.

If, and only if, you know it accurately locates GoTo targets, but you find that it drifts so badly in declination that it bothers you, continue with the next step
Quote:

Do the All star polar alignment routine, and use the mount's Alt and AZ adjustment knobs to phsyically centre the scope on the ASPA star.



The step after this can be informative - it can tell you how accurate your ASPA polar align was - but isn't really necessary. For visual it may be interesting, but doesn't matter practically unless grossly off; for long-duration photography, you'll probably want to drift align anyway. Drift alignment doesn't rely on the accuracy of the mount's pointing model, which is built from your alignment and calibration (and why you don't want to ASPA if GoTos are inaccurate).

Do the 2 + 4 alignment and enjoy. Don't bother with precise polar alignment unless there's an actual need or you just *want* to do it (which I sometimes do).


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Jon_Doh
scholastic sledgehammer


Reged: 09/16/11

Loc: On a receiver's back
Re: AVX Latitude Scale Question new [Re: SkipW]
      #6080074 - 09/14/13 09:54 AM

I really appreciate the replies and advice that's been given. I'm going to try the suggestions made here and see what works the best. Being anxious to try out the mount after sitting inside for almost a week due to rain and clouds last evening it finally cleared up so I took the scope and mount out to test under a bright moonlit sky.

For a quick and dirty test I pointed the scope to magnetic north since I couldn't see Polaris from my drive, set the latitude to match my location and aligned the markers. For alignment stars I let the scope slew to its recommendation of Arcturus, centered it in the finder, then eyepiece. It wasn't too far off when the scope slewed to it. For the second star the scope recommended Vega, but it was too high in the sky and I didn't feel like sitting on my butt to center it so I chose Antares instead. Then for a calibration star I selected Altair and stopped there.

To test alignment I directed the controller to the moon and it put it dead center in the eyepiece. There was too much light in the sky to see much, but I looked at a few clusters. Everything was dead on except for M13, which was in the eyepiece, but not centered. I was quite pleased with my quick and dirty alignment and I'm sure the 2+4 method might have been more accurate.

Now I do have a question not related to alignment, but to the hand controller. The display wasn't bright enough to read it. When I checked the brightness it was turned all the way up to 8 and yet the display and keys are not bright enough to read. I played around changing the settings and only made it worse before returning the setting to 8. My Meade controller is very bright by comparison. Is this how the AVX is or do I have a defective one? Am I missing another setting to increase brightness? At this point I am very happy with the AVX, except for not being able to read the display.

Thanks.


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