GSO 'StellaLyra' SuperView

[Nightspore]

 

 

The Guan Sheng Optical ‘StellaLyra’ 30mm SuperView weighs in at a respectably lightweight 285g. It has a claimed 68° AFOV with five lens elements in three groups. The coatings seem like the usual GSO ‘green’. There is a purported 22mm of eye relief (which seems fairly accurate) and I make it 100mm tall with a folded down rubber eye-guard. The eye lens is 30mm and I measured the field stop at 35mm.

 

 

The overall aesthetic is a straightforward design with a smooth aluminium barrel. Guan Sheng Optical have been gradually phasing out all of their barrel undercuts for some time now.

 

 

The more recent undercuts usually featured ‘Tele Vue’ style lower-lipped flares, which aided extraction. GSO seem to have decided to replace all of them with smooth barrels. The upper housing features a rubber grip. My best guess is that the design is some form of Erfle. The internal baffling is competent and it features a 'filter' thread.

 

 

The SuperView series has been a huge success for GSO in the main and they can be purchased under various brand names. I have a pair of ‘Altair’ 15mm SuperViews for my binoviewer. However, the SuperView line has been criticised by some for displaying edge of field astigmatism, particularly in faster scopes. Although why anyone expects Tele Vue Panoptic type performance at GSO prices is a bit of a mystery. The 30mm ‘StellaLyra’ seemed like an answer to a particular problem for me. I wanted a lightweight 2” eyepiece around 30mm for rich field viewing with short tube refractors. The weight is important to me as I have a physical disability. Heavy eyepieces can also affect balance on light mounts. Ideally I wanted to fit a small travel scope with accessories into a lightweight bag not exceeding five kilograms in total.

 

 

GSO threads are usually pretty compatible with each other, but it was a bit of a ‘no-brainer’ that my 2” GSO Barlow element would be able to thread into the 30mm SuperView. Although this does add to the overall weight slightly it saves me carrying another 2” eyepiece. Depending on whether this diminishes the focal length by 1.6x or 1.5x (the jury’s still out) it reduces it to an 18.75mm or 20mm focal length. I tried the Barlow originally with a 32mm GSO RK (Reversed Kellner). The 32mm GSO RK is lightweight, and I like its ergonomics. It produces a bright and well contrasted image. It can also produce the ‘floating in space’ effect often reported in other reversed Kellner designs. Unfortunately it suffers from seagulls the size of pterodactyls in anything faster than f/8. Adding the Barlow element shoots many of the avian dinosaurs down but the fastest scope I can actually use it in is my 80ED DS Pro Evostar (f/7.5). I originally tried the RK in my f/5.8 72ED DS Pro. The results were far from satisfactory. It kind of reminded me of the scene in Star Wars when the Millennium Falcon jumped into hyperspace and all of the stars stretched out into long white lines. I’m not joking.

 

 

On Wednesday the third of January I thought I was in with a chance as it was predicted to be clear for around an hour. Although my several different weather forecasting apps couldn’t actually all agree on which particular hour exactly (eventually I got well over two hours outside). So I ventured out with my modified ST80 and AZ5 mount at 18:00 GMT.

 

 

The transparency was below average with a few scudding clouds and the seeing was about Antoniadi II~III. The first target (without the Barlow element) was Cr 70 aka the ‘Serpent Cluster’ in Orion’s Belt at 13.3x. To my relief there were no seagulls and well over 70% of the field showed no discernible off-axis astigmatism, although to be honest I tend to observe on-axis predominantly. The field stop is not sharply defined but this isn’t unusual with GSO eyepieces. The Pleiades and Hyades (Melotte 25) were stunning. I spent some time in Cassiopeia, Perseus and Auriga. NGC 559, NGC 663, the Owl Cluster and the Double Cluster all looked excellent with good colour separation and were sharp and well contrasted. I managed the Andromeda Galaxy and later even got a hint of the Crab Nebula through rapidly diminishing transparency. I added the Barlow element (for about 20~21x) and revisited most of what I’d observed earlier and M42. I was pleased to discover that there was no really obvious vignetting, although it pushed the eye relief out a bit more. The 30mm GSO SuperView isn’t a 27mm Panoptic, 28mm ES or 31mm Baader Hyperion Aspheric, but I didn’t expect it to be. OK, maybe a few baby seagulls; it can display a small amount of astigmatism near the edge of field. I thought it did well in a short tube achromat and a pretty good 2” eyepiece for just under seventy quid. Definitely a keeper.

[Nightspore]

The GSO 32mm RK (below left next to the 30mm SuperView) seems roughly the same weight as the SuperView.

 

 

Reversed Kellners are often maligned but they aren't so bad in slower scopes. The three element design can give a bright, sharp, well contrasted image with an AFOV of 56°, regardless of some disingenuous OEM claims of 65°.  They are more suited to slower scopes however and can fare badly in anything much faster than f/7.5. The GSO RK's are still available under various brand names. 

 

 

I believe the 28mm Synta LER is a reversed Kellner. I think the GSO SuperView series was specifically designed to be an economic alternative to the RK. 

 

 

When it finally stops snowing I'll review the 42mm in my Evostar 72ED DS Pro. It's supposedly good up to f/6. The 72ED is f/5.8. 

 

We'll see ...

Edited February 7, 2021 by Nightspore