2" Apochromatic Barlow

[chunkylad]

Hi everyone

I have a 26mm x 2" GS EP, that I love for it's panoramic views. I would like to add the 32mm and 40mm x 2" GS eps to my collection. To enhance their versatility and usefulness, I want a 2", 2X Barlow to complement them.

Surfing the Aussie websites comes up with several achromatic 2" Barlows. To my mind, I'd be wasting my $$$ unless I get an Apochromatic type.

Anyone have any ideas on brand names/performance/suppliers(home or O/S) of decent 2" barlows?????:help:

Cheers
Dave W

[Starkler]

Dave47tuc recently bought a 2 inch barlow that he seems quite happy with.
He wasnt impressed with the gso 2 inch barlow.

http://www.iceinspace.com.au/forum/showthread.php?t=2395

FWIW the 40mm gso wont be of much use in your scope unless its barlowed and then eye placement may be difficult due to the eye relief being extended by the barlow.

[chunkylad]

Thanks Geoff

I had the idea that the 2" Barlow would be more 'useful', (ie I could use it with all my eps) than a 1.25" unit.I had not thought about, or correctly understood the effect of the barlow on eye relief.

Is it wise to pursue this course, or should I be looking at a 1.25" Orion Shorty (for example), and plump for better 1.25" ultrawide eps, over the 2" types?

[ausastronomer]

Dave,

I would look at the GSO Superview line of eyepieces. Note that the 2" GSO superviews perform better than their smaller 1.25" brothers. They are not much more expensive than what you have and infinitely superior in any scope and under all conditions. With an F5 scope you don't really need an eyepiece with a focal length much over 30mm due to the large exit pupil it creates.

What I would do is try and sell your existing 2" 26mm eyepiece (they are very average) , buy a 2" 30mm GSO Superview (about $80 or $90) then look at the 2" barlow that Geoff has directed you to, the GS barlow you are considering is also pretty average. Realistically I think if you spent more money on those 2" Kellner designed GS eyepieces (26mm,32mm and 40mm) you would be taking an enormous step backwards, they are not remotely close to being able to deliver the view quality that your scope is capable of.

CS-John B

[Starkler]

I agree with John. Dont buy any more of the gso "budget line" , they are about the worst I have seen for abberations at edge of field. I used to own the 26mm myself.

I'll give Dave47tuc a nudge and see if he will relate his experiences comparing his UO barlow to the Televue big barlow belonging to a friend of his.
Maybe when I catch up with him we can compare the UO 2 incher to my Celestron Ultima 1.25" in use with 1.25" eyepieces. It helps to have a planet around to observe though :shrug:

[Dave47tuc]

Hello here I am :whistle:
The University Barlow I have is very very good. I have not had a chance to compare it to a TV big Barlow. Hope to over summer. We are having a bad winter :windy:
The few times i have used it. Very pleased with the Images :thumbsup:
People say Oh don't bother with a 2" Barlow and wide field EP's :poke:
I say rubbish the views i get a very good and sharp. I still get a good field and eye relief. I highly recomend this Barlow.

Go to http://www.frontieroptics.com/
I got mine from Daniel he was very helpfull. The UO Barlow is half the price of a TV Big Barlow. And I reckon just as good. :D

[chunkylad]

Thanks guys

Any thoughts on the Andrews line of UW eps? The 2" items are selling for $149. There is a new 15mm UW 2" ep on the way. Or their ED (don't know what that ED stands for btw:P ) eps, for that matter?

It's so much easier to ask those of you who have used these eps before, and get unbiased answers. I don't know of a better way to 'shop' for technology.

I am also going to try to get a look through as many different eps as I can at our next observing night.:poke:

Cheers

[elusiver]

Extra-low Dispersion.. i think :shrug: With the andrews prices best to call him up as the web prices haven't been up dated in a while. I think asimov got one of the andrews ED eyepieces.. or ones which look quite similar to the ED eyepieces in the andrews ad in AS&T.. which also look alot like these (http://cgi.ebay.com/Seben-1-25-ED-Eyepiece-High-Quality-99GBP_W0QQitemZ7538641583QQcategory Z3636QQssPageNameZWDVWQQrdZ1QQcmdZV iewItem).

el :)

[asimov]

Yes, but I got mine from AOE..But they call them an ED-2 rather than an ED. I can testify a 9.5mm in an F8 scope works great. (I cant speak for any of the others) Rotten weather here at present, so no test in my F5 done as yet.

[davidpretorius]

Hi dave, I have andrews uw 30mm. My favourite eyepiece. I know I know the rest are all series 500, but for $149, i love it and feel i got very good value for money.

My wife had looked thru the 6.5,12.5,25,40 and as soon as she looked thru the ultra wide, she says that this is now her favourite!!.

I am keen down the track to give the 15mm ultra wide a go when it arrives.

Lovely wide views. I let it cool like my scope and do not have any complaints.

I am a noobie, and until snake valley, have not looked thru naglers etc, but I am being very honest in how impressed i am with the ultra wide.

[chunkylad]

Adrews is selling their ED eps for $99.oo each, per their ad in Sept AS&T.

[asimov]

That's 20 bucks too dear..:whistle:

[Starkler]

Dave may I suggest that if you have only ever looked through series 500 plossls before, anything else is going to impress :whistle:
Im seriously not trying to be smart here.

[ausastronomer]

Dave,

Be carefull buying the cheaper widefield eyepieces for use in your F5 scope. These budget widefields do not work well at faster F-ratios like F5. The best budget priced semi-widefield eyepiece for use in your F5 scope are the GSO Superviews which are sold by Andrews and Bintel. They only have a 65 deg AFOV compared to an 80 deg AFOV of some of the budget widefields but an 80 deg AFOV is no use when the outer 50% of the FOV contains nothing but out of focus seagulls. Your best option IMO for starters is the 2" 30mm GSO Superview. I own 1 of these and whilst not quite as good as my 27mm TV Panoptic it isn't $500 either. It performs exceptionally well considering its price and importantly works well at F5 giving sharp views over at least 80% of the FOV.

CS-John B

[davidpretorius]

i can only detect seagulls in last 5-10% roughly. i think el has one, he lets it cool with his scope and he really loves it too.

as i have said and geoff rightly points out, i am comparing to series 500 eyepieces that came free with the scope. At the moment $149 was well spent, maybe from looking thru a $250 one at snake valley i will go, well if only i had spent $100 more.

If you remember i am a noobie too, and hence my comments are from that persuasion.

Search the forum for andrews ultra wide 80 degree 30mm. I even think there is a review on the main site that is well worth a read.

[davidpretorius]

found it

http://www.iceinspace.com.au/index.php?id=42,134,0,0,1,0

http://www.iceinspace.com.au/forum/showpost.php?p=33260&postcount=18

http://www.iceinspace.com.au/forum/showthread.php?t=2904&highlight=ultrawide

it was not EL, it was ballarat dragons (ken)

[iceman]

I've had possession of (for a few weeks) both the 2" GS SV 30mm, and the Andrews UW 80deg 30mm, and they were both "ok" in my f/5 10".

The views were quite good, but there's no doubt the stars weren't sharp to the edge. It just depends how much you're willing to put up with the distorted shape of stars near the edge of the view.

While the Andrews UW80 had a wider FOV, it also had seagulls deeper into the field. The GS had a narrower FOV (67deg as opposed to 80), but the stars were sharper wider to the edge.. so the actual area of FOV that had sharp stars, was almost the same.

So, for the dollars, I'd probably go the GS 30mmSV, as you can usually get it on sale (or second hand) for $79. The Andrews 80 is nice, and it's a big hand grenade of an eyepiece, but for $150 i'd probably save up and spend $300 on something of a little more quality.

But if you're on a budget, the GS SV is as good as you'll get for the price, in a f/5 scope.

[ausastronomer]

Mike,

Is that Andrews 30mm the same as that 30mm 1rpd thingy that Anthony owns ?

CS-John B

[iceman]

I believe so John, yes.

[Starkler]

If you buy second hand you can get top quality equipment and lose little or nothing if you later decide to sell it . Quality gear holds its value better.
I had a Televue 27mm panoptic that I owned for 18 months, and sold it for $10 less than I paid for it. Not a bad rental cost over 18 months :)

[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. :thumbsup:
------------------
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]

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]

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

CS-John B

[bytor666]

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!!! :jump: 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]

Mark, How come the size of the adapter changes the magnification of the same set of optical elements? :confuse3:

[bytor666]

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]

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]

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 :thumbsup:

[Dave47tuc]

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. :thumbsup:

[BC]

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]

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

[chunkylad]

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

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

[BC]

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]

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]

Well nothing :rolleyes: 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. :D

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 :thumbsup: 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 :poke:

[stringscope]

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]

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]

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.