what does an extender do?

[prbaxter]

ok i read about people removing lenses from their barlows to create an extender...

to what purpose?

[AstroGnome]

If you find that you can't get your scope to focus because the focuser wont come out far enough you will need to put an extender on it to get further out. A common problem for some camera set ups

You can buy extenders designed specifically for the job but a quick way to do it is to unscrew the lens part of the end of a barlow (which many people already have) leaving you with a tube that can be fitted to the focuser.

[prbaxter]

ahhh... so thats why the lens unscrews from my barlow.

[AstroGnome]

Indeed, but on your Explorer 150 you may find you have the opposite problem of not getting the focuser to go in far enough. I did with my 130m

[prbaxter]

guess that depends on your altitude?

(that me and funny physics humour again!.. ha haaa haa)

[AstroGnome]

I'll need a pint before I get it...

[prbaxter]

actually I'm not sure it makes sense, doing some quick research on the matter...

but do have a pint or two and let me know if you make any progress on it.

[Freff]

ok i read about people removing lenses from their barlows to create an extender...

to what purpose?

You will also find that the Barlow will also screw into your camera T-ring doing away with the T-ring adapter and reducing vigneting in the process.