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Zhumell Dob 10 - why can't I see anything through my eyepiece? (used laser collimator)


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Hi all,

 

We've been using a Meade EQ telescope we found at a goodwill for some time and had the urge to upgrade after going to an astronomy night and seeing Saturn's rings. For my birthday, we got the Zhumell DOBSONIAN 10". Put it together, used the laser collimator I think correctly to collimate. But for some reason when I look through the eyepiece I can't see anything? What on earth am I doing wrong? We've only used the 1.25" one that came w/ the Z10, but we do have a Barlow as well. It has a dual Crayford but honestly I don't know what it is or how to use it. Getting frustrated already. The EQ we just carried out, set up, used the finder and then focused the image and that was that. 

TIA for any input

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It is difficult to diagnose over a distance like this especially without pictures. If you were collimated incorrectly -- off my a little bit, not wildly wrong-- you would still get some kind of image. 

What you are looking for here is another Zhumell user who knows by experience what an inexperienced person does wrong the first time. 

Is there someone you can go to in person, like at a local astronomy club? I know that with Covid and all, they are not all active in person, but just for instance, when I pick up and drop off stuff with our equipment chairman, we wear masks and all that. It's not impossible. 

 

Edited by mikemarotta
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Collimation, as Mike says above, is not the issue here. You should see a decent image even if the scope is not collimated that well.

What we need to know is what you DO see though the eyepiece when you point the scope at a bright star or the moon using a low power eyepiece, that is the eyepiece with the longest focal length, eg: 25mm or 20mm or similar rather than 10mm, 6mm etc.

The most common issue with scopes not showing much at all is that the incorrect adapters are being used to hold the eyepiece so sharp focus is simply not achieved. This is why, again echoing what Mike says, a photo of your focuser with the eyepiece in place, as you have used it, will also help diagnose the problem.

Of course these scopes can and do work extremely well otherwise they would not be so popular :icon_biggrin:

 

Edited by John
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Try focusing on a distant landmark during the day.

That will get you familiar with using that focuser, and will be close to the slightly different focus point for infinity objects such as the moon and stars.

The Dual Crayford probably has a Coarse Focus and a Fine Focus knob.

Try turning them and look for movement of the focuser tube.

If there's no movement there is probably a handscrew that needs tightening.

If it still doesn't come into focus, have a look for a picture in the Instruction Manual that shows the focuser with an eyepiece in it - do you have any spacers missing, or  spacers inserted that aren't required ?

Michael

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  • 3 weeks later...

I’m fairly new at this and have the same scope.   I’m guessing that you got the 30mm wide view and the (iirc) 6mm.  Start out with the 30mm piece in the focuser.   There’s one of the set screws on the focuser that locks it in place.   The focuser knobs will spin, but the tube won’t move.   Check your manual (it is also online as a pdf) to determine which is the lock screw, it will be easier for you to find it from their picture than for me to describe it to you.   The focuser is dual speed.  The big knobs are for coarse adjustment, the small for fine adjustment.   The big knobs are pretty accurate and precise.  Mess around with it when you aren’t trying to see anything with it and sort it out.

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Hello @saw9 and welcome to SGL.

During the day find a distant object - at least half a mile away-  in the finder.

Now put the highest number eyepiece you have in the focuser and see if the scope will focus - you may need to remove an extension tube in the focuser to do this.

When it does come to focus pick an object and place it centrally in the view, then without moving the scope adjust the finder to centralise the same object on the crosshairs.

You are now good to go.

Edited by dweller25
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