Extension Tube Advice

[Shibby]

I'm looking at buying an extension tube to increase the magnification of my barlow for planetary imaging. I've found this one: Ascension 1.25" Extension Tube.

Looks like it's 28mm; how much will this increase magnification? (it's a 2x barlow).

There is also this: Antares 1.25 diameter extention tube | Telescope Accessories | Rother Valley Optics, which is 55mm - is that too much?

Is ~£20 typical for a tube? Don't see any on astroboot...

[lukebl]

Have you got an old cheap barlow lying around? Like the ones that come with most scopes. Just take the lens out and use that. That's what I do.

[Stephen]

Have you got an old cheap barlow lying around? Like the ones that come with most scopes. Just take the lens out and use that. That's what I do.

Seconded.

The only extension tubes I was prepared to spend money on were 2" jobbies from FLO (£18 ish for either the 50mm or 80mm lengths.)

[Shibby]

I don't... however, I can see one on astroboot for £4. Thanks for the tip!

(assuming the lens is removable on it...)