Celestron Travel Scope 70 eyepiece 20mm disassembled

[Yuka]

My son got a Celestron Travel Scope 70 as a gift. He disassembled eyepieces:( I have no idea how to fix this. Could anyone have any idea how to fix this eyepiece? I think 10mm is ok but I am not 100% sure. 20mm is completely disassembled. Thanks!

[Alien 13]

As a general rule of thumb the most curved part of each lens goes in the middle and the flatter part towards the eye and scope.

Alan

[Knighty2112]

I think I might know the answer, but why did your son take the EP's apart?

From memory I think the larger lens goes in the EP first as this is the one nearest to your eye, then the smaller lens goes in on the spacer, then it should be fixed in position with a plastic screw thread (can't see this  in your picture), then the metal barrel screws on to the bottom of the EP. 

[ronin]

This site looks simplest: http://www.billsastro.com/Astronomy/Equipment/Eyepiece Folder/eyepiece_design.htm#Huyghens

If the eyepiece has a H on it then it is a Huygens, if a K then it is a Kellner, some may say R or SR treat as a Ramsden. The diagrams show the lens arrangement for each. Doubt it is a plossl. I expect it to be a Kellner.

Just make sure it is clean and free from dust, hair and finger prints before you reassemble. That is not as easy as it sounds.

[Cosmic Geoff]

If it's any help, I took apart the 9mm Celestron and 10mm Sky-watcher eyepieces that came with the scopes. The 9mm wasn't very good, so I wondered what was inside.  I carefully noted the arrangement before reassembly and made a sketch.  Both had a single lens and a doublet, with the single lens nearest the eye, and the curved surfaces inwards against the spacer. I don't know what this design is called; it's like a Kellner but backwards.  

If the lenses aren't the same size, on a low-power eyepiece I'd expect the smaller lens to be nearer the eye - they're like that in Huygenians.

If they're ruined, replace them with Plossls for about £20 each or less, or from Astrojumble - it'll almost certainly be an upgrade. Don't spend too much as it seems the whole outfit costs less than some eyepieces.

[Dave In Vermont]

A 'reversed' Kellner constitutes the design from a line of eyepieces from Edmund Scientific - starting in the 1960's (if memory serves) - called the 'RKE' eyepieces. They are said to be good, but I've never had the chance to try one.

As for the disassembled one, I notice it's the stock 10mm that often comes with telescopes. If you can't get it up & running, don't sweat it. These usually are rather lousy to begin with, from the reports I've read & heard. Maybe your son was trying to figure out why it gave poor views?

May a better eyepiece be on your horizon,

Dave

<EDIT> I just noted it is the 20mm eyepiece that was mangled. I only was reading from the bottom one - which does say 10mm. Mea Culpa!

[Paz]

Kids are designed to be curious - it helps them to learn. Look at how much we are all learning about eyepieces due to this curiosity!

[Yuka]

Thanks everyone. I am overwhelmed how helpful all are. Yes, my son is 6 and he said he was very curious. As upset as I was and still am, we will now hopefully learn how to fix telescope. Hopefully...I will try tomorrow and update here. Thanks all!!!

 

[Louis D]

Just be careful to not let the lenses get wedged in at an angle.  You'll likely chip them trying to get them out.  The best method is to stack them on a 1" dowel and carefully lower the barrel over the stack of lenses and spacers.