2" Apochromatic Barlow - Page 2

bytor666 · #21 21-08-2005, 03:42 PM

Somebody here said that the 2" GSO barlow was not that good. I have one of these and it is an excellent 2" Barlow lens. I wouldn't get rid of it ever. The diff between an apochromatic barlow and an achromatic one are so minimal...it makes no difference, and I have been observing for years.

------------------
Mark
12" Gso scope
15x70 Oberwerks
10x50 Magnicons
14mm UWA (4000) and 8.8mm UWA (4000's)
30mm 2" GSO eyepiece on the way

chunkylad (David) · #22 22-08-2005, 10:18 AM

Are there any other issues to consider when using the 2" Barlow + adaptor for 1.25" eps, rather than a dedicated 1.25" Barlow, like the Shorty Plus?

Cheers

ausastronomer (John Bambury) · #23 22-08-2005, 11:20 AM

Only the weight, some 2" barlows are quite heavy and can affect the balance on smaller dobs, making them nosedive.

CS-John B

bytor666 · #24 22-08-2005, 11:39 AM

Theres actually no issues at all with a 2 inch barlow lens...its even better than a 1.25" one.
I have 2 dual-barrel eyepieces. A Meade 14mm UWA and also a Meade 8.8mm UWA. With the 2 inch GSO barlow I can get 6 magnifications out of the 2 eyepieces and the barlow.

14mm UWA = 112x / 45'
14mm UWA (with the 2 inch skirt in the 2 inch barlow) = 217x / 23'
14mm UWA (with the 1.25" part in the 1.25" adapter of barlow) = 258x / 14.5'

8.8mm UWA = 174x / 29'
8.8mm UWA (with the 2 inch skirt in the 2 inch barlow) = 320x / 16'
8.8mm UWA (with the 1.25" part in the 1.25" adapter of barlow) = 380x / 13.25'

Then with a 2 inch eyepiece ill be getting the equivalent of two more eyepieces....which will bring the total to the equivalent of having 8 eyepieces!!!

as far as balance issues go, i have no problems at all because I use a counterweight bag on the back of the telescope tube , along with a couple of magnets.
------------------
Mark
12" Gso Scope

janoskiss (Steve H) · #25 22-08-2005, 11:45 AM

Mark, How come the size of the adapter changes the magnification of the same set of optical elements?

bytor666 · #26 22-08-2005, 11:55 AM

The magnification changes when you put an eyepiece further back from a barlow lens.
here is a link for you to read from the GURU himself!!!....cheers!!!
http://www.atmsite.org/contrib/Carlin/barlow/
-----------------
mark
12" Gso Scope
15x70 OBERWERKS

BC · #27 27-08-2005, 03:20 PM

I've just ordered a 2" 2x University Optics barlow from Frontier Optics. Is this going to work OK with my GSO EPs (32mm, 15mm and 9mm) or are there issues? I'm going down the "buy as good as you can afford" route, but I'd hate to get something that was incompatible for some reason.

Starkler (Geoff) · #28 27-08-2005, 05:53 PM

BC I doubt that anyone here can answer that for you. The only person I know of who owns this barlow is dave47tuc. He uses his with naglers/panoptics and is quite happy with it. At least you know now that the barlow wont be the limiting factor in the views that you get

Dave47tuc (David) · #29 28-08-2005, 08:25 AM

Quote:

Originally Posted by BC

I've just ordered a 2" 2x University Optics barlow from Frontier Optics. Is this going to work OK with my GSO EPs (32mm, 15mm and 9mm) or are there issues? I'm going down the "buy as good as you can afford" route, but I'd hate to get something that was incompatible for some reason.

BC the UO Barlow does not come standard with a 1.25" adaptor. You have to but this seperate. I got mine from Bintel but ask Daniel if he can supply one.

Happy viewing.

BC · #30 29-08-2005, 10:26 AM

Starkler, fear not, I'm getting over my blame-the-tools phase. It's been a blast lately. Not that keen to go down a path of optics combination that others haven't been down though. And now I notice from Dave that it doesn't come with an adapter. I've just chickened out and ordered a GS 2", Frontier hadn't put their order in yet. I promise not to complain about the GS unit.

janoskiss (Steve H) · #31 29-08-2005, 10:52 AM

What's wrong with using the adapter that came with your focuser?

chunkylad (David) · #32 29-08-2005, 11:02 PM

Quote:

Originally Posted by janoskiss

What's wrong with using the adapter that came with your focuser?

Yeah........what he said, or errr asked!!!!!!!!

What's wrong with the thingy that came with the focus whosit???

BC · #33 30-08-2005, 08:23 AM

Well, probably nothing is wrong with the adapter I already have. I just don't want to spend $150 and then find out that.."oh, this Barlow doesn't work with those EPs" or "that adapter won't work because.....". I'm happier going with combinations that others have tried.

Miaplacidus (Brian) · #34 30-08-2005, 09:01 AM

Just a bit of extra info for anyone thinking of buying the UO 2" barlow. Daniel from Frontier Optics informs me that it won't come to focus with quite a few of the short tube refractors (positioned either before or after the diagonal).

Happy observing,

Brian.

Dave47tuc (David) · #35 30-08-2005, 07:21 PM

Quote:

Originally Posted by janoskiss

What's wrong with using the adapter that came with your focuser?

Well nothing

I just stated that the Barlow does not come with a 1.25" adaptor. I brought one because I wanted to! and used it as a cap as well. I now have two 1.25" adaptors and happy about it.

I looked through a gs barlow and a gs 9mm once at our Vic meet some months ago. Out of 10 I give it a 2. Compared to my barlow and 8.8 UWA.
The GS combo not even in the ball park.

What type of gs 9 mm it was I don't know. Other issues re mount movement was a problem also. I have read many reviews on the GS barlow and all sound good. Mark is happy with his

Again Mark uses high end EP's also.
That makes a diffrence also. I see the Barlow not the problem but the EP's.

Most people don't bother Barlowing 2" EP's so if you don't need a 2" Barlow there are a lot more 1.25" Barlow out there.

My 0.02c with a few years observing under my belt

stringscope (Ian) · #36 30-08-2005, 09:51 PM

I have both the GSO 2" and the Celestron Ultima 1.25" Barlows. I have used these with a variety of eyepieces (Synta to Nagler) and I have not noticed either of them producing undesirable abberations during use.

Cheers,

Starkler (Geoff) · #37 30-08-2005, 10:25 PM

Quote:

Originally Posted by Dave47tuc

I looked through a gs barlow and a gs 9mm once at our Vic meet some months ago. Out of 10 I give it a 2. Compared to my barlow and 8.8 UWA.
The GS combo not even in the ball park.

I looked through the same GS barlow with my pentax XL 14mm at Jupiter, then compared the same ep with my Ultima barlow. The GS exhibited considerably more light scatter and was like observing through a fog by comparison.

AstroGuy · #38 08-03-2011, 01:10 PM

Quote:

Originally Posted by bytor666

Somebody here said that the 2" GSO barlow was not that good. I have one of these and it is an excellent 2" Barlow lens. I wouldn't get rid of it ever. The diff between an apochromatic barlow and an achromatic one are so minimal...it makes no difference, and I have been observing for years.

------------------
Mark
12" Gso scope
15x70 Oberwerks
10x50 Magnicons
14mm UWA (4000) and 8.8mm UWA (4000's)
30mm 2" GSO eyepiece on the way

I have a GSO 5x 1.25" apo barlow and it does work well too, of course if you combine an apo barlow with a achromatic eyepiece it will defeat the purpose if chromatic aberation is what you're trying to avoid.