Adapter help needed.

[Doc]

I'm looking for a little extention tube to put on the end of my 2" to 1.25" adapter. The reason being is once I screw a filter onto the 2" end and insert an eyepiece it just touches the filter. So I have to keep the eyepiece slightly out of the adapter, but sometimes I forget.

So anyone know of one going cheap, or has one not being used, or any links to one.

Just to recap it must screw onto the 2" end of the 2" to 1.25" adapter and increase it by about 10mm.

[themos]

Why not use a parfocalising ring to keep the eyepiece from going too far in?

[Psychobilly]

or a couple of "gash" 2" filter rings threaded together? I found 2" and 1" long 2" barallel extensions but guess they are too long...

[Doc]

Why not use a parfocalising ring to keep the eyepiece from going too far in?

I thought parfocalising rings had no thread you simply secure with a grub screw to the barrel.

[themos]

yes...

[Doc]

Would this simply screw onto the bottom of the 2" to 1.25" adapter. Is a T2 thread the same thing?

Adaptors - Baader T2 Extension Tube

[Doc]

yes...

I could but then the eyepiece is not completely inserted in the 2" to 1.25" adapter I want it fully inserted.

[Doc]

or a couple of "gash" 2" filter rings threaded together? I found 2" and 1" long 2" barallel extensions but guess they are too long...

Slightly to long Peter, looking at 10mm or there abouts.

[Psychobilly]

a couple of gash filter should be ok with the glass removed... may get away with one...

[AWR]

TS have this (and every other known adapter). Bit pricy though!

Verlängerungshülse - 2" Filtergewinde - 10mm Länge - Teleskop-Express: Astro-Shop + Fotografie + Naturbeobachtung

Andrew

[Psychobilly]

Vorsprung .....

Extension Tube - 2" - Filter thread - 10mm Length - Teleskop-Express: Astro-Shop + Fotografie + Naturbeobachtung

[Doc]

Thats the one but 29 Euro's a little to much. Do you think those FLO ones will work I linked to?

If not a 2" filter like Peter has mentioned.

[AWR]

T2 is too small (M42x0.75) compared to 2" filter thread (M48x0.75)

Andrew

[Doc]

T2 is too small (M42x0.75) compared to 2" filter thread (M48x0.75)

Andrew

Thanks Andrew.

[pvaz]

I been looking for one of this to extend the Ethos 2" barrel and use a parfocal ring so I can get the extra out travel needed to focus instead of using it with the 2" to 1.25" adapter.

Ironically the cheapest I found was from Televue:

TeleVue Eyepiece Barrel Extender - 2" - EBX-2120 - OPT Telescopes

[Andrew*]

I had exactly the same problem as you, Doc. The TeleVue one was the only one I could find. Look at the bottom: TeleVue Eyepiece Accessories

[johninderby]

Alternatively a high profile 1.25" to 2" adaptor. It's 45mm from top of 1.25" part to bottom of the 2" end which should give plenty of clearance. They're £15.00.

http://www.astronomica.co.uk/index.php/Accessories/Adaptors/1.25-inch-to-2-inch-Adapter-Long-Profile.html

John

[Doc]

I measure it I can get away with about 3mm so I'll lokk towards a 48mm filter.

[Andrew*]

You'd almost be better getting a cheap set of 2" planetary filters and smashing the glass out of them!

[AWR]

You could try a longer profile 2" - 1.25" adapter (assuming you have enough in travel to focus).

1.25 inch to 2 inch Adapter (Long Profile) | Adaptors | Accessories | Astronomica

(I've no idea how long this is - it just looks longer)

Andrew

Beaten to it - Too slow at typing! This is the same one John is suggesting!

[Doc]

Good idea Andrew but then John's strange looking adapter aint bad for £15 but would it work or would it change the focal distance as the eyepiece would be sticking out more.

[Andrew*]

You would need more in-focus for that arrangement.

[Doc]

You would need more in-focus for that arrangement.

I do suffer from In focus problems hence why I couldn't use the skywatcher coma corrector.

[johninderby]

The measurement between where the 2" section seats into the focuser and the top of the 1.25" part is 19mm, so compare that to the adaptor that's being used now.

John

[Doc]

I will John...

I also found this filter on e-bay, thinking off removing the glass and just screwing this onto the bottom of my 2" to 1.25" adapter. The sides look at least 5mm high which will be enough.

Hoya 48mm polarising filter, new on eBay (end time 11-Apr-10 19:08:46 BST)