Guan Sheng SuperView 68°

allan gould · #1 03-11-2006, 12:25 PM

Anyone had any experiences with these eyepieces? I'm interested in the 2" 50mm. Any comments welcome

janoskiss (Steve H) · #2 03-11-2006, 12:34 PM

Probably better off with the 2" 42mm. About the same TFOV but greater AFOV. I've only used the 30mm. It's good in f/8 or slower. Still okay at f/6, and even in f/5 if you must a widefield and cannot afford to spend $100s on something better. You will have to put up with lots of seagulls though at f/6 and faster.

anj026 · #3 04-11-2006, 09:36 AM

Hi Allan

I have the 50mm and it is a good eyepiece for the money but the eye relief is huge making it difficult to use. I have not tried the 42 mm version but do have a 40mm GS reverse kellner (3 elements) which is even cheaper and for me more comfortable with great througput. The 50mm could be modified with a cone on top to position the eye better.

regards
Andy

ving (David) · #4 04-11-2006, 10:14 AM

i have the 30mm and as steve stated, at f6 you get a fair few seagulls at the outer 10% of the FOV where as the 15mm 1.25" is good to the edge in my scope. threfore i asume (maybe wrong) that the 50mm would be worse(?). what sort of telescope do you have?

allan gould · #5 04-11-2006, 08:10 PM

Many thanks for your input. Scopes? Too many and another on the way, thats why its raining in Brisbane.
10 and 8" SCT, 3" apo and 4" achro refractors. f7-f10

ballaratdragons (Ken) · #6 04-11-2006, 11:45 PM

I too have the GS 30mm Superview and it is a great EP if you don't mind seagulls in the outer 30%.

What I did find interesting though is that if I put my GS seagull 30mm into my GS 2" 2x Barlow the seagulls fly away (probably after someone elses chips).

But that is defeating the purpose of having a widefield EP in the first place.

stephenmcnelley · #7 06-11-2006, 09:42 PM

I like many went and bought a few of the SV's as general purpose and loan eyepieces some time ago, to be honest the 15mm sv is hopeless across the board, even at f11 or more, but if you dont mind spectacular distortion across 50+% of the FOV it isnt that bad a DSO EP.
The 20mm is a much better EP although at f5 it suffers across 20-30% fov too, less field curvature though and very contrasty, an acceptable cheap EP suitable for the FF's.

I really doubt all these EP's offer the 68" FOV that they claim, my Stratus 17mm offers a markedly wider field than either the 15 or 20mm GSO's, as yet i havent measured TFOV with them, as others previously have and posted their results.

My 30mm GSO sv is a good search and find EP, but for the price dont expect to much in terms of off axis views.
I have owned and tried some of the GSO reverse kellners, IMHO they are shockers of things really, but cheap and cheerful with easy eye relief.

I agree with janoskiss about considering the 2" 42 mm, heres a bit of a link that publicly tests eyepieces- http://www.excelsis.com/1.0/entry.ph...cba52b9b8a503a

Then again there is also a number of more optically corrected 40 odd mm plossl type 1.25" EP's ranging from $60-$140. Meade make one and i am told it is supposed to be very nice and a real keeper, The 2" EP market is a bit of a gimmick in some ways, but we all love grenade size EP's and big lenses.
Good luck and clear skies in BrisVegas.

allan gould · #8 06-11-2006, 10:43 PM

Stephen et al
Thanks for the replies. I have a Meade 40mm 1.25" and as you say above it is a keeper, but I just wanted to know what the lower end 2" eyepieces were like. From the Sky & Space review Dec 2004 it looks like the best value for money in the 2" stakes would probably be the Andrews UW 30mm eyepiece. At $149 its not a huge outlay for what was termed an "optically excellent" eyepiece

anj026 · #9 07-11-2006, 12:51 AM

I agree with Stephen that the claimed FOV is not what is sometimes claimed with these cheaper eyepieces. I don't think it is possible for a 50mm focal length 2" barrel eyepiece to be 68 degree FOV and it seems more like 52 to 54 degrees to me. I think the 40mm reverse kellner is supposed to be 65 degrees but again it is seems a bit less.

I forgot to mention in my previous post that I am using these eyepieces in a 6" f15. The long focal ratio goes a long way to minimising the problems with these modern incarnations of old eyepiece designs.

The 30mm Andrews UW is another good value eyepiece in my opinion but it is heavy and this can bring it's own problems when swapping eyepieces around during a session depending on your scope set up.

regards