I'm sure this will be an embarrassing question, but I can't work out what *it* does.

[IC1101]

By it, I mean this!

After a lot of googling (without knowing what to call it), I'm assuming it's a 2" Focuser Adapter?

I mount it onto my telescope and proceed to place either my 10mm 1.25" lens or my 25mm 1.25" lens - yet I can't focus on anything.

What do I do with it? I haven't seen 2" lenses anywhere.

Can I get it to work with my 1.25" lenses?

[Allan_L (Allan)]

Hi there,
Yes it looks like an eyepiece adapter.
Perhaps it is a 1.25 inch adapter. (allows you to put a standard 1.25 inch eyepiece into a 2" focuser).
Some people (especially with skywatcher DOBS) don't realise they have to remove the 2" adapter, before putting the 1.25" adapter into the focuser tube.
Therefore, they can't bring it into focus.
That is, they cannot be used together.

See if this is the case for you.

[Marko of Oz (Mark)]

Looks more like an extension tube to me. Do your 1.25" eyepieces fit in the focuser without that part?

cheers.

[GraemeT (Graeme)]

It looks very much like the 2" adapter which comes with the Skywatcher dobs. What telescope are we talking about? By the way, WELCOME to Ice In Space!!!

[julianh72 (Julian)]

That looks like a 2" eyepiece adapter as used on Celestron telescopes, among others.

My 2nd-hand Celestron NexStar SLT 130 would originally have had both a 1 1/2" and 2" version of the adapter, depending on which eyepieces you want to use, but I only got the 1 1/2" adapter - I guess the original owner lost the 2' adapter because they couldn't work out what to do with it either! If you only have one size of eyepieces and accessories, you never need the other adapter, so it would be very easy to lose over time.

The adapter fits straight into the rack-and-pinion focuser and is held by two large thumb-screws in the focuser, and then the eyepieces fit straight into the adapter and are secured using the two smaller thumbscrews of the adapter.

When you say you can't focus your 1 1/2" eyepieces using this adapter - do they fit securely into the adapter, or do you need to use a 2" to 1 1/2" adapter tube? If you have to use an extension tube to get the 1 1/2" eyepieces to fit, it may be positioning them too far away to be able to rack in to achieve focus.

The attached photo shows my 1 1/2" adapter in my NexStar SLT 130 with a digital camera installed - you can see that the eyepiece / camera has to be very close to the top of the adapter to be able to reach focus.

[omegacrux (David)]

With my dob you remove the 1,25 and fit that in its place for 2in eps

David

[IC1101]

Thank you all for the responses! So it is a 2" focuser adapter after all.

Originally Posted by Allan_L

Hi there,
Yes it looks like an eyepiece adapter.
Perhaps it is a 1.25 inch adapter. (allows you to put a standard 1.25 inch eyepiece into a 2" focuser).
Some people (especially with skywatcher DOBS) don't realise they have to remove the 2" adapter, before putting the 1.25" adapter into the focuser tube.
Therefore, they can't bring it into focus.
That is, they cannot be used together.

See if this is the case for you.

This makes a whole lot of sense as I couldn't focus any of my eyepieces when the adapter was connected!

Thank you all for your help and also for the warm welcome.