Focuser Travel: Not Enough.

[Lowstar]

I`ve recently bought a 2" eyepiece. Sadly i`m around 10-15mm short of focus at full extension. Any extenders i`ve saw are starting off around 50mm so this still won`t solve the problem. ( instead of focuser fully out it would be fully in:() Does anyone know of a solution that would keep the eyepiece fully "home" in it`s seat as i don`t want it in a dodgy position as it cost a few bob.

The focuser is a Crayford on a 8" Orion dob.

Thanks in advance,

will.

[NGC 1502]

Hi, you can judge exactly how much extension you need if you focus by

sliding the eyepiece outwards from the focuser (keep hold of it !!) until

you get a sharp view. Then measure acurately the distance you have

slid the EP out.

I had the same problem with my low power 2" EP and fitted two parfocal

rings. They are 4mm deep, this gave me 8mm, and I can now focus ok

with a bit to spare. It still leaves over 20mm of chrome barrel inserted

into the focuser, which I'm ok with.

Like you, an extension tube would have been too long.

Don't know if this will work for you, but thought it worth posting.

Cheers, Ed.

[simon84]

Have a look on the astroboot over at scopes n skies website, I've seen a 2" nosepiece extension that screws into the filter thread on your EP which will then allow you to pull the EP further out of the drawtube knowing there is still plenty in there.

HTH.

[Chris H]

Not a cheap solution but I had the same problem so I bought a Moonlite focuser. Prior to that I made a small ring which held the ep, it was a Skywatcher Nirvana 28mm so a pretty heavy chunk of metal and glass, just the right amount out of the focuser tube.

[Moonshane]

you can always use the Baader fine tuning rings which work a treat on dual barreled EPs like the 13mm Ethos too.

[wulfrunian]

Why wouldn't the 50mm extension be any good? It's what I use - if you were 15mm short with the focuser fully out, then adding the extension tube means you'd reach focus by having it 35mm further in, hasn't it got that much travel distance?

[Lowstar]

Thanks, that`s a few solutions to the problem:hello2:

Wulfrunian.

I got the lend of a Revelation 50mm extension tube and as i described earlier it didn`t solve the problem, i was still that critical few mm short of focus, only at the other end of the scale as it were.

Thanks again,

Will.

[markymoo]

You can get a 35mm one from here:

Verlängerungshülse - 2" - 35mm Länge - Teleskop-Express: Astro-Shop + Fotografie + Naturbeobachtung

In fact they do three different lengths. As it happens I just got a 50mm one from them today, and it seems good. Sadly, I ordered it thinking I would be using a 2" diagonal, but I've loaned that to someone and am needing more extension again to use a 1 1/4" temporarily.

Still, seems cheap enough, and has compression rings rather than screws so I'm happy with it.

Mark

[Lowstar]

I don`t like those little screws either Mark. The compresson ring seems a better patent and they seem to be appearing on more and more astro stuff, and not just the expensive top end stuff.

ATB,

will.

[markymoo]

Well my 35mm one will be enough to get my 2" diagonal in focus, but it isn't really enough with a 1 1/4" diagonal that I'm using temporarily. I have to pull all the joints out a little bit to give me more length.

As that isn't a satisfactory solution I ordered a 50mm one from FLO today:

Adaptors - Two-inch Focus Extension tubes

It's a little cheaper than the German one, but looks to be about the same quality. Definitely worth a stab as they don't cost much anyway.

Cheers,

Mark