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Alignment issues with Etx90


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#1 Mattorrin

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Posted 01 July 2014 - 12:59 PM

Hi,

I recently purchased an ETX90 and have been unsuccessful in using it effectively.
I attempt to align it in the alt/az way and when it chooses stars, it goes to the correct spots, verified with my phones Google sky map app. However, when it does both stars and it says alignment successful the motor still runs and I can't use any of the functions. If I choose a direction on the controller, the scope will start to move in that direction and continuously move in that direction. I trained the drives and still the same.

Thoughts?

Also, I have a 26mm stossel lens. I don't feel the views I have had are too great, or at least I thought it would be better. Am I gonna be able to use a better lens or am I stuck with what I have?

Thanks

#2 MistrBadgr

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Posted 01 July 2014 - 04:05 PM

Hello, and welcome to the Forum!

 

I am assuming this is a new scope.  With the warranty in effect, call Meade Customer Support at 1-800-626-3233.

 

With a new scope, do not mess with this.  Get a replacement or at least talk to them about the problem and see if they have a fix.

 

As far as eyepieces go, the scope will handle any eyepiece with a 1.25 inch barrel.  I expect they have supplied one of the 4000 series 26 mm Plossles, which are normally good eyepieces.  The 4000 series comes in different focal lengths that give you different magnifications.

 

Are you wanting higher magnifications, wider views,....?  Let me know and I will explain things in the direction you want to go.

 

Best Regards,

 

Bill Steen


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#3 Mattorrin

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Posted 02 July 2014 - 06:09 AM

Thanks Bill,

I actually called them already and first experience was useless and frustrating. That's why I came here. I'll try them again and be more forceful.

I AM trying to get wider, clearer views. As opposed to just seeing a bigger bright spot. :). I suppose once I get things working right, I should investigate lenses.
Thanks

#4 gspie

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Posted 02 July 2014 - 07:24 AM

There are lots of choices out there. I have eyepieces from both the 400 and 500 series. The 5000 series are really nice, however the ultra wide-angle 30mm (82-degree) weighs in at about 4-lbs (requires 2" adapter) 


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#5 Mark Sibole

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Posted 02 July 2014 - 09:33 AM

For a wider FOV you need a 40 mm EP.It is a strong scope in magnification.As for your motor problems have you tried aligning it without it being connected to your phone or PC????

Try first with out any pc or phone heeked up.It should go to alignment done then just start tracking.If you tap the nsew buttions it should move in that direction then stop when the button is released.If it keeps moving it could be a bad motor board or keypad.Call Customor service and tell them I said to call to resolve the issue!

 

Regards

 

Mark Sibole


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#6 RickScofield

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Posted 02 July 2014 - 01:00 PM

I can attest to the 5000 series eyepieces for the ETX 90, the view with these is outstanding and exceeds that of the 4000 series. I had problems with my ETX 90 as well with it going in circles, I called and they had me send it in and MEADE determined it was a bad board that couldn't be replaced so they replaced my ETX90 with a new one.

I was impressed on how MEADE stood by their warranty and replaced my telescope. If your using the 497 Autostar controller and having this issue after alignment I would urge you to give MEADE another try.         



#7 MistrBadgr

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Posted 02 July 2014 - 05:56 PM

Mattorrin,

 

Just a few thoughts about eyepieces with your scope.  If the ETX 90 has a weak spot, it is with getting a wide field of view.  With a focal length of 1250, about the best you can do with a 1.25 inch eyepiece is 1.4 degrees of actual sky and that is with a 40 mm super plossle like the Meade 4000 series.  That eyepiece, however, is limited to a 44 degree field inside the eyepiece, which can seem a bit cramped.  A 32 mm super plossle has about a 50 degree apparent field of view inside the eyepiece, and the rest of the series are 52 degrees.

 

The 5000 series HD 60 eyepieces that Rick has start with a 25 mm eyepiece and go down to 4.5 mm and all have a 60 apparent field of view (inside the eyepiece).  The 25 mm gives you a magnification of 50X and a true field of view of not quite 1.2 degrees.  Those eyepieces are all good for general viewing of most things from 25 mm down through the 6.5.  The 6.5 mm gives a magnification of 192X, which is about the limit of your scope on a good night for everything except the Moon.  With the really bright Moon light, the 4.5 mm can be used under good conditions to give you a magnification of 278X.  That magnification is right at three times the diameter of your scope in millimeters.  A good rule of thumb is the diameter of your scope in millimeters is normally about the upper limit for magnification of everything but the Moon, and three times the millimeters is a general maximum for lunar viewing.

 

For wider views than the 40 mm plossle can give, the best option is to have another, shorter focal length scope.  The scopes I use mostly have a focal length of 800 mm or less, just to get that wider field of view for things like the Plieades star cluster, which is about 1.8 degrees wide.  For most things, the 1.2 degree true field of view (width of the chunk of sky) that you can get with the HD 60 25 mm is plenty.

 

Your ETX 90 should do well with the higher magnifications of Moon and planets.  To get anything better would require a larger diameter scope (less portable) or a long focal length refractor (also less portable).

 

You can get a wider looking view with 70 and 80 degree views inside the eyepiece, but there is simply a limit on how much sky can be stuffed inside a 1.25 inch eyepiece.  As the width of the field inside the eyepiece goes up, the width of actual field diminishes slightly simply due to geometry, and the maximum focal length of the eyepiece gets shorter.

 

To sum things up, the Plossl eyepiece is a good design for most things and the most widely used design.  It gives the best bang for the buck out there.  However, something like the HD 60 is better in many ways, but does cost more.

 

There are other designs, like orthoscopics, that are really good planetary eyepieces with a narrower field of view than plossles, and Erfles that are wider field and reasonably priced, but not as good for planetary things.  The list of possibilities goes on and on, but it is hard to beat the Plossles for economical general viewing and the HD 60 series for a good step up in image quality.

 

I hope that is not too much and overly confusing.  If so, holler back with questions and I will try to explain my way out of the confusion.

 

Bill Steen


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Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma




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