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Problem with HEQ5 Circles....

daz

By daz
in Discussions - Mounts

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daz

daz

Posted
Posted

...which I know are not the most accurate of things, however, last night was the first time I actually used them in anger.

I polar aligned and set the DEC circle, no problem - and indeed when I rotated the scope and brought it back to 90, it still pointed to Polaris.

The RA circles are a different story. Once I had set them to a known object (M42 for example) and rotated the scope round, they were off when I brought them back to the same object. It appears to slip as the tube rotates.

Anyone else come across this before, and how did you / do I overcome it??

Cheers

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daz

daz

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Yes Gaz there is.

Tightening seems to have no effect - other than too tight and then the circle does not move at all. I don't know what the internals look like so I don't know if locking the screw fully down is supposed to engage against something else, ergo I'm not tightening the screw enough !!

If I leave it loose, the circle rotates, but slips!

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lunator

lunator

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Daz

I'm no expert but on my EQ5 I have found that the best way to use them is to find a bright object and check the Dec & RA on the circles are correct for this.

Move the scope to another target (something slightly less bright) and see if the reading is still accurate. If it is then you can find most objects using the setting circles.

One caveat is that I always recheck circles if I am moving to a completely diffierent area of the sky (more than 45 degrees)

This seems to ensure that the circles remain well aligned. Although sometime it is just quicker to star-hop :clouds2:

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daz

daz

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Sorry Andy, bit confused now!!

Surely the set circle DOES move with the RA drive, otherwise, as you say, RA would be out by the time elapsed. Ergo, when you point to M42 and set the circle accordingly, the pointer still points to the correct reading as time passes.

It doesn't seem to matter how quickly I move the scope, the circle is out when I move it back to a known object (provided I have moved by more than just a few minutes).

Perhaps it's finding the combination of correct tension and speed ... ?

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GazOC

GazOC

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It's still tracking though in RA isnt it Gaz.. Maybe i am missing the point here? :clouds2:

James :clouds2:

Yep, I've confused myself as well!! :clouds2:

When the motor tracks on object the RA circle should stay at the same value. When the mount is moved manually to a new object the RA circle should move.

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daz

daz

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When the motor tracks on object the RA circle should stay at the same value. When the mount is moved manually to a new object the RA circle should move.

But this would mean the circle would point at an incorrect division on the scale as time progressed. If you wanted to use the circle to move to a new object, you would have reset the circle to the current object BEFORE moving to the new object !!!???

It MUST move with the motor, surely?

Example:

Locate M42 (05 35)

Set circle to 05 35

Wait 10 minutes

If the circles DOES NOT move, the pointer will now point to 05 45

If the circle DOES move, the pointer will now point to 05 35

Jeez - this is hurting!!!!! :clouds2:

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The Warthog

The Warthog

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Generally, my RA setting circle moves with the scope when I am using the slow-motion controls, and stays more or less still when I slew the scope (manually, of course) This is as it should be, and seems to be engineered by some cunning device in the RA axis. I can also slip the setting circle around to correct it. When I am following something with the slow motion control, and if I bothered much with the setting circle, I want the setting circle to follow the scope. I don't want this when I slew the scope, because then I am going to a new coordinate, and don't want the setting circle to move. If I am watching an object, then the RA doesn't change, and the setting circle should move with the scope.

Hmm. I can see I explained that about as well as I explained RA to Twinkletoes.

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The Warthog

The Warthog

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I don't use my setting circles, but surely they shouldn't move when the motor is on as the RA of an object moves at the same rate as the motor moves the mount? They should just move when you are moving the scope to an object?

Nope. The opposite is true, like as the man says here:

Yep, I've confused myself as well!!  :clouds2:

When the motor tracks on object the RA circle should stay at the same value. When the mount is moved manually to a new object the RA circle should move.

Which is what I said, only more clearly.

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daz

daz

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Daz,

I think we're at cross purposes!! I think were agreeing with each other....the RA needs to move but not change value. is that how you see it?

Gaz

YES!!!!

:clouds2: :clouds2: :clouds2: I think you were right - we both said the same thing, just badly!

So, (now that we all understand how RA circles work..... :clouds2: ) onto my problem.

Why does mine NOT rotate back to the same value when moved a reasonable distance???

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