[ATM] What's up with my Barlow?

[Mike Shuken <mikeshuken@value.net>]

Hello,

I just finished my first telescope build, a Dobson with a 4.5" f/8 
mirror.  It's as Dobson as it gets, plumbing parts focuser, etc. but the 
first time I threw it on the moon it was "Yeah, baby!" that's what it's all 
about...

Anyway, I have two eye pieces, a 10mm and a 25mm.  Good views of Jupiter, I 
can see the bands but no spot, and the moon is great.  So I figured to make 
the moon bigger the next best thing besides crushing my eye against a 6mm 
EP is to buy a Barlow 2x.  I picked one up for a few bucks figuring that I 
would just "plug it in" fiddle with the focuser and double my moon crater 
size.  The Barlow arrived in the mail and I spent an hour trying to get it 
to work to no avail.  All I get is a big fuzzy bright spot that has no 
viewable features at all.

The Barlow is an Orion, 2x Barlow Lens 1.25 Fully Baffled.  A photo of it 
is here:

http://blog.mannon.com/archives/000008.html  (scroll to the way bottom, 
ignore other postings unless something looks good and you want to buy it, 
like that Chevy motor that caught fire...)

I always assumed that a Barlow lens (any 2x 1.25 Barlow lens) would but my 
focal point right about where it was with the standard EP, but I have 
worked that thing up and down four inches with the 10mm perched on top and 
again, nothing.

What's the trick with a Barlow?  What am I doing wrong?  If I purchased an 
incorrect piece for my telescope what do I look for in a proper one?  Since 
I don't know a whole lot about telescopes, maybe this Barlow is faulty, and 
if so how can I test for that?

Thanks in advance,

Mike


_______________________________________________
ATM mailing list http://www.atmlist.net/