GSO 2" barlow

[MattT]

The 2" ED GSO barlow the lens can be taken off and screwed onto a 2" eyepiece giving roughly 1.5X. What do you get with putting it onto a 35mm 2" extension tube? Is it 1.7X? or a bit more. The barlow is on a 50mm tube to start with.
Matt

[AG Hybrid]

Sounds about right. A nifty barlow indeed.

[cometcatcher]

I found by mucking about with various extension tubes it can be anything from about 1.5x to 2.7x.

[bytor666]

Hi Matt.

I have dome this exact thing and it gave me 1.88x magnification on most of my eyepieces.

[MattT]

To continue this old post…..

I have one eyepiece I like to use with the 2" GSO Barlow…the ES 28mm 68º.

With the barlow as is …hmm not bad but a bit rough round the edges, which is not so good and had..past tense…me not using it much at all…until now.

As Kevin says..'mucking around with various extension tubes'…so I tried it, with a great result.

Using a f5 4" refractor (tough test for eyepieces) and my beloved 28mm 68 I tried the barlow lens screwed to the eyepiece…too much FC to bother. Then added a 35mm extension tube to the regular barlow (with 50mm tube) that is 85mm all up and got pinpoint stars to the edge…wow...totally unexpected. Might just be this eyepiece that has this result, but have a new found love for the 2" GSO 2X ED Barlow.

[bytor666]

What's even better is the 2" ES 2x Focal Extender, or Meade 2x 2" TeleXtender. I tried the Meade with a 2" 28mm ES 68 and it cleaned the edges right up in my 10" F/4.7 reflector.

I was amazed at how perfect the edges were when using the 28mm with the 2" 2x Focal Extender. The FE is a bit heavy, but it is worth the performance difference!

Cheers!

[Nungers]

Anybody tried a 17mm eyepiece in a 2" barlow

[MattT]

Never tried a 17mm but I do have an 18mm ES 82º eyepiece that is great on it's own…will have to try it soon.
By my visual rough reckoning…to me it seems the not so great 2x 2"ED Barlow with a 35mm extension tube turns into a very nice 2.5x Barlow.

[Nungers]

Might try and buy a 17mm or around that, dont seem to be that common.

[MattT]

Weakened and bought the ES 2" 2x FE....took advantage of the ES sale and the $20 USD postage from Agena Astro with no box, about $60-80 USD with the box :screwy: Arrived in perfect nick in 8 days.

Now to compare the GSO to the ES...when the clouds clear.

[bytor666]

Let us all know what you think m8! :D

Cheers! :)

[doug mc]

Time a star across the field of view with said eyepiece, then screw in barlow in any way, with or without adaptors and make the timing again. A little math and you have the power changes.

[Don Pensack]

Timing without barlow/Timing with barlow=magnification factor.
This one can be used:
Threaded on the eyepiece
Threaded onto a 1.25" adapter
In its own tube in front of the eyepiece
Threaded to the front of a star diagonal
In its own tube in front of a star diagonal.
So in some scopes, it can be used to yield a number of different focal lengths for the eyepiece.

Throw in some barrel extenders (about 10 different lengths of these available, from 14mm to over 50mm), and you could almost create a whole collection of eyepieces with only one or two eyepieces.

Unfortunately, not all distances of the lens from the eyepiece are free of vignetting, or spherical aberration.

[MattT]

Only had a short time to use the ES 2" FE. Brilliant in a word. Exactly what I want. No eye placement troubles at all, just a great view. Turns the ES 28mm 68º into a very nice 14mm. Best of all sharp to the edge...unlike the GSO as a 2x.

In short the GSO is pretty near perfect with a 35mm extension tube in it (giving roughly 2.5x) and the ES 2x FE is perfect as is :thumbsup:

This is in my 6" f12 Refractor. Next to try both in my f4.8 10" Newt....with and without a Coma Corrector.

Matt

[bytor666]

BRILLIANT !!! :eyepop: :D ;)

CHEERS!