Re: [ATM] What's up with my Barlow?

["Jeff Baldwin" <bald@olypen.com>]

If you are using a star diagonal between the barlow and the eyepiece, there
may not be enough travel to come to focus.  Your focus would be way too far
back, and it would no longer be a 2X barlow.  If this is not the case, then
nevermind.
JBald

Jeff and Glenda Baldwin
Beaver  WA
bald@olypen.com
glendabaldwin@olypen.com
http://olypen.com/bald

----- Original Message -----
From: "Mike Shuken" <mikeshuken@value.net>
To: <atm@atmlist.net>
Sent: Thursday, June 23, 2005 10:30 PM
Subject: [ATM] What's up with my Barlow?


> 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
>
>
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