EP "review"

[ving (David)]

2" GS superwide 30mm eyepeice from Andrews.

last night during the briefest relief from rain and clouds i risked taking my telescope out to test my brand new GS eyepeice. To be honest I expected the views to be similar to my 1.25" Celestron 30mm so I did a side by side test.

The sun had only just recently set and the sky was only just dark enough to make out my first target naked eye, m42. Now I dont claim to be an expert on telescopes or anything but I do know how to spot differences , so heres what i looked for when comparing:

*size of FOV
*seagulls stealing chips at the edge of the said FOV
*contrast
*eye relief
*general clarity
beyond this i am pretty useless.

Size of FOV: with m42 centered in the eye piece the 2" stertched from just below yale 1898 to just above 49 Ori. the 1.25" celestron stretched from just below 42 Ori to pretty much right on 49 Ori.

seagulls(?): both eyepieces had a similar outcome here. about the last 7-10% there was mild er.... seagulling

contrast: now heres where the 2" shines... or doesnt but the nebula did.. or something. m42 was noticabley brighter in the very light sky compared to the celestron piece. there was more contrast between the cloud strewn sky and the nebula too. the difference was significant.

eye relief: was pretty poor in the GS piece, having to push my face right up agianst the (comfy) rubber rubber cup to see the entire FOV. the relief on the smaller EP is considerably better. not that this worries me one bit.

general clarity: crystal clear image to right near the edge. high contrast too. cant wait for a cloudless moonless night!

$99 @ andrews. bargain!
man is it huge and heavy tho!

ps: I need a 2" moon filter after being nearly blinded!

[Striker (Tony)]

I think your spot on ving.......you cant go wrong for the price....$99

I got mine from Sirus Optics for $99 plus the 2" 2 x GS Barlow for $79.......

What I would like to know is when I was talking to Bintel about these GS eyepieces they said the 30mm is good but the GS SV 42mm 2" is crap..they wont carry the 42mm they sent them back and said that the budget GS 40mm was better then the GS 42mm superview......their opinion changed regarding the 30mm SV comparing to the GS budget 32mm.......I just dont know why....

As you can see by the website they stock the whole range of GS but not the 42mm SV?

[gaa_ian (Ian)]

I have the 2" GS 40mm from Andrew's (not badged with Andrews)
I have been very happy with it (Until I got my UO Konig 40mm
)
But the difference is not huge.

[iceman (Mike)]

*seagulls stealing chips at the edge of the said FOV

Great review, thanks Vingmeister. It looks like i'll have to look at getting one of these myself.

but the GS SV 42mm 2" is crap..they wont carry the 42mm they sent them back

It might have something to do with the exit pupil size, which apparently is not good on fast scopes.. Mark Hodson might have some more info on this.

[Starkler (Geoff)]

exit pupil = (eyepiece focal length) / (scope focal ratio)

So for a 42mm eyepiece at f5 , exit pupil = 42/5 = 8.4mm

Another way to calculate the same thing is (aperture) / magnification.

mag = 1250/42 = 29.76 , 250 / 29.76 = 8.4

Nobodies pupils will dilate enough to allow an 8.4mm exit pupil and the other factor is that the size of the shadow of the scopes secondary is also getting big which hampers viewing.

Try looking through your scope with your lowest mag eyepiece in daylight to see what I mean.

In general terms the best views come with exit pupil size less than 6mm or so depending how dark your observing location is. Go bigger and the sky background washes out and becomes grey instead of black. Furthermore, your eye is vignetting the light and you are effectively loosing telescope aperture.

This is why we look for wide field eyepieces especially at longer focal lengths to keep exit pupil size down.

[mch62 (Mark)]

I have the 42mm GSO SV (see review section) and don't find it crap.(what are they smoking)
I use it in my f6 Newt and my f7.5 refractor and find it 's performance great.
It is not a TV or other super high priced EP , but it is certainly not crap.

Yes exit pupil size in an f5 will be a determining factor although I have tried it in an f5 GSO Dob and it was still OK for me at least.
Didn't see the Central obstruction , only on the moon , but obviously it will be coming into play at f5 .

The 30mmm would be a better proposition for the f5 Dobs .
I don't have a 30mm GSO SV but have used one and the quality between the 42 and 30 was the same in both of my scopes.

May be there crap because they weren't selling and every one went to the opposition for a cheaper price?

Mark

[ving (David)]

Originally posted by mhodson
The 30mmm would be a better proposition for the f5 Dobs .
I don't have a 30mm GSO SV but have used one and the quality between the 42 and 30 was the same in both of my scopes.
Mark

yes, yes the 30mm is a better proposition

[Striker (Tony)]

"Warning"

If anyone is interested in the GS 2" Superview's be careful purchasing at Sirus Optics Underwood Brisbane.....he has been selling the GS Budget's as GS Superviews for $125

Just make sure you get the right one......

On the other hand his GS Barlow 2" are well priced at $79

[Starkler (Geoff)]

I got the 26mm "GS budget" but it wasnt called that at the time and it cost me $140 !

That was when I discovered what was meant by "seagulls" . I quickly decided I needed to get a 27mm panoptic after that.
Maybe if the gso superview was around then I may not have shelled out for the televue ep.