GSO Superview Ep's

[acropolite]

I've just taken delivery of my LX90 :D and have only the standard 26mm Plossl EP. I was thinking of getting an GS0 superview 15mm and GS 2x Barlow as a stopgap measure until I can afford something better.

Will the GSO superview work OK in the meade and give me reasonable performance with the 2x Barlow.

How would the 15mm/Barlow combo compare in performance to a 7mm eyepiece.

By the way we've had the driest March on record here in Tas and since the LX arrived its been continuously overcast and it's forecast to rain tomorrow. :rain:

[mch62]

Can't coment on the 15mm , but I have the GSOSV40mm with GSO2X barlow and have used it in my f6 with good results alone or with the barlow.
It's even better in my f7.5 refractor .
Used it in a Sc a few weeks back and was very impressed with edge performance considering the price.
Will be able to tell you more tomorrow , as to night Striker comes over for a night viewing. He has an f10 Sc and we will be doing a comparo between the GSO , Andrews 30mm and his new family of Nags , in his scope an f6 newt and my 80mm f7.5 refractor.
Basically using a cheaper 4 or 5 element EP with a good barlow is going to improve it's edge performance in fast scopes so an f10 is not a real problem.
What your doing is basicaly what a AL Nagler has done by combining an EP and barlow together to make a better corrected EP.

[ausastronomer]

Hi Phil,

If your looking for a budget priced eyepiece that has a reasonably wide AFOV these will do a "fair" job in your F10 SCT. If you can't afford premium eyepieces you have 2 options.

1. Go with a lesser quality eyepiece that has a reasonably wide AFOV and poorer quality images (eg GSO Superview) or

2. Go with a top quality eyepiece with a narrow FOV (eg UO HD orthos or Ultrascopics etc)

On the basis that your scope being an F10 CAT has an inherrently narrow FOV you may wish to go for the 1st option. If you don't mind a narrow FOV but want excellent image quality the 2nd option is by far the better.

I tested the GSO 15mm and 20mm Superviews at SPSP in my own F5 scope and wasn't that impressed with them. While the edge performance would be improved a lot in a slower scope like your F10 Cat the on axis performance was only reasonable compared to both my UO HD orthos and my pentax's. Certainly a "good" orthoscopic or plossl albiet having a narrow FOV will walk all over the 1.25" GSO's in terms of sharpness, contrast and light transmission. Its worth noting that the 2" GSO Superview's perform a lot better relatively speaking than their 1.25" little brothers IMO. I own the 2" 30mm GSO Superview and it does a very good job even at F5 for a budget eyepiece.

Having said all of the above and probably given you the impression I don't like it much, if you want something that is reasonably cheap, has an AFOV over 55 degrees and has fair eye relief they are probably still the best option for you. I just didn't want you walking in and buying them with a misconception that they perform at 90% of the level of a premium eyepiece for 10% of the price because they aren't close to that. They do a good job at a budget price which may be what your looking for. Personally I would think about an 18mm UO HD ortho for about $120, narrower FOV, infinitely better images right across a tack sharp FOV in your F10 CAT

CS-John Bambury

[xrekcor]

Hi Phil,

I have the 30mm GSO SuperView which I find excellent. I was going to add the 20mm and 15mm to my collection. Until the
more I read and heard what people had to say about them was
they dont cut it like the bigger 2" 30mm. So I went another way.

If you can stretch to the AUS$130.00 mark and dont mind a smaller FOV with good contrasty views. Think about a 12mm UO HD Ortho. It makes a great planetary (barlowed) and faint dso ep.

[acropolite]

Money's not really the problem it's the Minister for household affairs:ashamed:. Are there any Oz reselers that have UO eyepieces?

[Starkler]

I suppose now isnt a good time to sell my 20mm superview :P

Frontier optics import and sell UO orthoscopics

http://www.frontieroptics.com/

Considering the lx90 has a 2000mm focal length a 10mm eyepiece will give you 200x, which is as much as you can use with average seeing conditions.

A 10mm ortho would be nice for planetary, along with the 25mm plossl assuming reasonable quality should get you started.
Then you can start saving for a 24mm teleview panoptic :)

[acropolite]

My initial choice was a Mead series 5000 14mm UWA which Bintel have listed for $285. I've read favourable reports, in some of the cloudy nights forums, on that particular EP and it's a tad more easy to justify to the Minister for houshold affairs than the Teleview.
I also found a review on UO EP's at http://www.cloudynights.com/lab/eyepieces/orthos.pdf
More reading up required methinks. :P
Has anyone had a look at any of the Series 5000 EP's yet?

[ausastronomer]

The guy who owns Frontier Optics is a guy called Daniel Deringer. Daniel is a friend of mine and lives near me on the Central Coast. He plans to join the forum and our little Central Coast observing group that we are trying to get happening. Tell him that I referred you to him and he will look after you, he is a very obliging helpfull type of person.



This was the reason I recommended the 18mm HD ortho as opposed to the 12mm. The 18mm will give him 111x native and 222x barlowed in his scope which are 2 usefull magnifications. The 1st for medium power views of DSO's and the 2nd for planetary. The 12mm HD ortho barlowed would be nigh on useless in that scope giving 333x which he would get to use maybe 10 times a year if he was lucky.


Clear Skies
John Bambury

[Starkler]

For the price of a barlow worth having he could have another UO ortho plus some change left over.

[xrekcor]

Phil,

John is right! let me apologise for giving you a bum steer.

I forgot to mention I use a 8" f/6 newt and the 12mm in that
gives me similar powers the 18mm would in yours. All the same
you cant go wrong with UO HD's. I own four of them 18, 12, 9 & 7 and dont regret buying any of them. Mind you, it's hard getting the new Pentax out of the scope

regards

[ballaratdragons]

I am one of many in here with the 2" GS SuperView 30mm EP.

I absolutely love it, but I have no other 2" EP's to compare it to, so in other words: I'm not much help!

Does anyone know if the 2" GS SV 15mm is any good for DSO's at f5? (and don't say "just barlow the 30mm, coz a 2" barlow costs a lot more than the 2" SV) or should I get the 20mm?

[ausastronomer]

Geoff,

Phil owns the GS barlow, I am not suggesting that he goes and buys a barlow, merely stating that the 18mm will work fine in his current barlow. The 9mm HD ortho would always be a better option than the 18mm barlowed in the GS barlow, but Phil indicated that he is presently looking for 1 eyepiece only.

CS-John B

[MintSauce]

The 15mm and 20mm are 1 1/4" eyepieces, the GS 2" barlow is good tho - and the 20mm is alot better than the 15imo. Get the barlow if you don't already have a 1 1/4" one.

G.

[Starkler]

Ken I have the 20mm 1.25" SV and agree with Johns assessment above. Not recommended at f5.

John, I read Phils original post as indicating he wanted to buy one eyepiece AND a barlow.

[ausastronomer]

Geoff,

I just re read Phils original post and your correct, he did plan on buying the GS 1.25" barlow and the 15mm Superview, apologies.

Phil,

I don't recommend you buy the 1.25" GS barlow, I have used it several times in a variety of scopes and with a number of eyepieces and can only rate it fair. You have a good scope in the LX90 so don't downgrade the scope by using cheap accessories with it. Its a bit like buying a Mercedes and then putting recaps on it when its 1st set of tires wear out, false economy. If you want to get a barlow the minimum I would consider is the Orion Shorty Plus which costs about $130.

Your best option IMO is to go and buy the 18mm and the 9mm UO HD orthos. This will cost you about $240, but the image quality is superb, albeit with a slightly narrow FOV. Sharpness, contrast and light transmission of these eyepieces is as good as any premium eyepiece and they deliver perfect star images across the entire field of view in scopes slower than F5 or so.

CS-John B

[acropolite]

I don't have a barlow yet, and from what I am reading it's probably unnecessary. I think the 18 and 9mm UO HD EP's sound like a good choice and maybe a GSO 40mm for wide field. Any recommendations regarding 2 inch diagonals?? :confuse3:

[ausastronomer]

Phil,

I don't own an LX90 but be very wary of using 2" accessories with it. The scope only has a 1.25" visual back, which also means it has a smaller hole in the mirror consequently a lot of 2" accessories may vignette with it, particularly longer focal length eyepieces, like 2" 40mm ones, so I suggest you test this out before you shell out your bucks.

The Williams Optics diagonal which Daniel Beringer also sells is excellent but its not cheap, but then good quality products never are, maybe around $200. Its as good as those produced by some other companies like Takahashi and Astro Physics but it costs a lot less. Your wasting your time with anything cheaper than this IMO.

CS-John B

[beren]

Congrats on the scope Phil , hope it serves you well and the weather is kind , you may like to join the LX90 group i think they have some tips in their file sections on checking/using/maintaining your new scope {eg: checking all the allen scres are tight , racking in your focuser in and out a number of times etc}plus recommendations on accessories.

I was thinking of getting the upgraded 2 inch visual back supplied by Petterson but i havent had indication of problems with my eyepieces {longest F-length 32mm meade SWA}. Wether its fact or not ive read that such a upgrade is only useful for SCTs 10" and higher. I ended up getting the Meade 2 inch UTHC diagonal but i wished i had brought the Williams , its a bit dearer but rates well , Frontiers sell them for 229 but are out of stock at the moment , you can import them from the US for around 210.

[acropolite]

There's nothing in the Meade documentation to suggest that this is the case. The 2" diagonal is listed as suitable for all LX models including the 90. The Lx90 optically is identical to the 8' LX200.:confused:

[Starkler]

I got my William Optics refractor diagonal a little cheaper than Frontier quoted from

http://www.atscope.com.au/

[xrekcor]

Check out there specials page

http://www.atscope.com.au/specials.html

They have some on special there...not sure if it is what your after

[ausastronomer]

Phil,

I am well aware that the OTA is the same as the 8" LX200. The same issues may also apply to the Celestron C8 and C9.25.

Do you really expect Meade to come out and tell you that there may be a problem here ? Come on, Meade have been copying other peoples designs and over exaggerating claims about their equipment for decades. Their latest one is their new RCX 400 which they claim is a "modified" Ritchey Chretien. By definition a Ritchey Chretien has a concave hyperbolic primary and a convex hyperbolic secondary. Meades new scope uses a spherical primary yet they want to put their hand up and call it a Ritchey Chretien, based on the success of this design by companies like Optical Guidance Systems, Parallax Instruments and RCOS. Meades Superwides introduced in the 80's were "very" similar to the Televue Widefields and the Meade Ultrawides were "very" similar to the original Televue Naglers, do I need to continue, or are you starting to get the picture of the company we are dealing with ?

I am not 100% certain that it is a problem, but I am about 80% sure that a number of people have minor issues using the 2" UO MK70 40mm in their 8" Cats. It is not the end of the world, you lose some light and stars at the EOF, but then why go to the low power widefield view if you dont get it all anyway.

I am merely trying to point out that this may be an issue before you part with your money. Try to get out to a star party and try out the components you are thinking of buying, even if its in a C8 or 8" LX200 or something, any CAT with a 1.25" visual back.

Clear Skies
John B

[[1ponders]]

Phil if you check out on of strikers old eyepiece postings there is a link that lets you work out the amount of vignetting from different 2" eyepieces. From memory up to 35 or 36 mm there should be no problem but more than that then vignetting starts to affect FOv. That's with all of the meade SCT OTA's (LX models) You can get around it by changing the visual backing to one with a larger opening. I'll have a dig around and see if I can find the link

Here it is. The crossed out eyepieces are the ones that are most affected by vignetting.

http://www.petersonengineering.com/spreadsheets/Eyepieces_for_8_inch_SCT.htm

Check out the "Eyeopener" page for more info
http://www.petersonengineering.com/SkyDiv/EO.htm

[acropolite]

Just had a look at that site Paul, thanks for that. John, it all makes sense now. The 8" LX opening on the back measures just under 2 inches, whereas the bigger meades have an opening that's 3". It's a minefield that's for sure. Is the field reducer useful for widefield or is it just for photography? Any recommendations for something in the 40mm range for widefield, or am I better to strap a refractor on top, or just forget anything larger than the standard EP.

[ausastronomer]

Phil,

The maximum field of view of a 1.25" eyepiece is approximated with a 32mm plossl having an AFOV of about 52 deg. There is a formula, you multiply the AFOV by the focal length of the eyepiece and for a 1.25" eyepiece the maximum value is about 1650, for a 2" eyepiece it is about 2800. ie 32 x 52 = 1664.

The 24mm TV Panoptic also approaches the maximum FOV for a 1.25" 24 x 68 = 1632.

Al Nagler from Televue recommends a 32mm Plossl or 24mm Panoptic as the best low power eyepiece for use in an 8" SCT. In your scope a 32mm Plossl will give a TFOV of 50' or .83 of a degree. This isn't too bad when you consider your scope is not designed as a rich field scope. If you went that way the best eyepiece would be the 30mm Orion Ultrascopic for about $200 from Sirius Optics in Brisbane or the 30mm Celestron Ultima. These eyepieces are almost identical and offer superb image quality.

If you want to go the 2" route there is no reason you can't use a 2" 30mm eyepiece. Something like the 30mm GSO Superview (65 deg AFOV) would give you a TFOV of just on 1 deg. But a $200 diagonal and a 2" eyepiece is a big shellout when you could buy a far better quality 1.25" eyepiece for a slightly smaller TFOV.
If it was me I would be going with a 1.25" 30mm Plossl and be happy with what I have.

The SCT is a wonderful all round telescope it does a very good job of most things telescope, an excellent job of no things telescope, but wide fields of view is one of the areas the SCT is not seen at its best. Use your LX90 for the things it does best. If you want a Rich Field Scope buy one designed for that specific purpose like the Orion ST80. This scope would give a TFOV of almost 4 degrees with a 30mm 52 deg AFOV plossl. Horses for courses.

CS- John B

[acropolite]

Thanks John, I'm pleased that I didn't rush in and order EP's with the LX. I can make an informed decision now. It would be nice to try out some EP's but I don't believe I have the opportunity in this area. The idea of a seperate wide field scope is attractive, especially as I can get double use as a spotting scope for HRH Liz who finds the Meade a little intimidating.

[beren]

Phils theres another angle to maybe give some consideration . A 6.3 focal reducer would save you money on purchasing longer focal length eyepieces plus serve a dual purpose if the astrophotophy bug bites in the future .When i was deciding on eyepieces getting the best eyepiece i could afford in the 20mm range was the catchcry for a F/10 scope. Ok i ended up with a 22mm nagler but team that up with a FR i just cant justify spending money on longer focal length eyepieces . If the budget is tight the stock meade 26mm plossl {one of my favourite eyepieces} with a FR might provide you with your low power setup, anywhy something to think about .

[trufflehunter]

Phil, I have the 2" WO diagonal on my LX90 and it is superb. A real work of art and worth every cent. Not only is it an excellent piece of optics, it's a nice bit of window dressing for the scope as well!

As far as 2" eyepieces go, currently I'm using the Meade QX 26mm (70deg FOV, MUCH better than the standard 26mm Plossl) and the 1rpd 30mm (80deg FOV). They both work brilliantly with the LX90 and there is no sign of vignetting. I'm waiting on a QX 36mm as well.

[trufflehunter]

woops! forgot to mention... make sure you get the SCT version of whatever 2" diagonal you choose to go with. Apparently some designs don't clear the fork base when the LX90 is pointing to zenith. The WO clears with about 2-3cm to spare.

[ballaratdragons]

I am hoping that the Andrews 2" barlow called the 'Andrews GS 2" Barlow' is the 'GS 2" Barlow'. Has anyone bought that particular model.

[MiG]

I have, and it is a 2" barlow from Guan Sheng optics. I hope that's helpful.

[ballaratdragons]

Good, thanks Mig. Andrews is advertising them at $79.

I will have to get one, as stated in posts above the 20mm and 15mm SV's are only 1.25".

[janoskiss]

$75 from AOE, acc. to their website http://www.aoe.com.au.

[syzygy]

Hmmm, I use a 2" diagonal on my C8 with 55mm Plossl and 32mm Erfle eyepieces and no trace of vignetting at F10.

I seem to recall the Celectron's detailed specs for the scope quoted an unvignetted field circle 2.75 inches in diameter. Could the Meade's rear post opening be that much smaller?

Regards,
Chris

[acropolite]

Wayne, Thanks for the feedback on the diagonal, which model WO did you get? Please let us know how the 36mm Qx performs when you get it. I am definitely going to get the focal reducer (thanks beren) which will be useful for my EOS as well. I hadn't considered the QX EP's but they seem very affordable. Anyone got any feedback on the 15mm Meade QX EP?

[trufflehunter]

I just got the standard WO 2", Phil, not the much more expensive dielectric variety. It's the SCT version that screws directly onto the visual back, replacing the original eyepiece holder. Ordered it from OPT. About $130US from memory, about $10US more than the Meade 2" model. Just realised too, I was a bit generous with my estimate of its clearance of the base of the fork arms... I said in my previous post it was 2-3cm... more like 15-20mm.

Yes, the QX's are great value in these scopes. I can't say what they're like in slower F ratios, however. I've become particularly fond of the 26. Nice wide field, sharp field stop, and only a very little softening of star images at the edge of the FOV... but only if you deliberately go looking for it. They're aren't too many ep's that don't suffer from that, even if you pay four times the price! I'll definitely let you know what the 36 is like when it arrives.