Eye Pieces

[oreed]

I am just buying a Nexstar 130 Slt and reading Ian Morison's comments he suggests a moonfish 30mm 80˚ eyepiece. I was just looking at these 2" eyepieces and was amazed at the weight, 570g (1.2lb). I understand from his comments that the Fork arm can take up to 5kg. Could someone tell me the weight of the scope on its own so that I can total up the weight on the arm.

Thanks.

[michael.h.f.wilkinson]

The (probably heavier) Vixen 130mm Newtonian has a tube weight of 4kg (complete OTA with finder). A 570 g EP should be OK.

[John]

I think that scope is an F/5 isn't it ? - the Moonfish 30mm 80 degree will show lots of astigmatism (seagull shaped stars) in the outer 50% of the field at that focal ratio I think.

That does not bother some people I know but it does some. You might find a 32mm 68 degree eyepiece like the Skywatcher Panaview works better.

[russ]

The 30mm Moonfish clone will not suit that scope really. It's every bit as bad as John says, even the central 50% being sharp is perhaps optimistic. Some folks can tolerate astigmatism, i can, but the 30mm 80deg takes it to whole new level in an f5 scope. I tried my best to tolerate it but it was truly the worst i had seen. Even the mega cheap Revelation 30mm Superview was better, although i couldn't tolerate that either (perhaps i'm not so tolerant after all). The Panaview John mentions is a fair option and the Adler 32mm 2" from Scopes'n'skies also works okayish. These are at the level i can tolerate.

[John]

You'll run into a far bigger problem before the astigmatism and weight ...... trying to fit a 2" eyepiece into a 1.25" focuser could pose something of a challenge.

Good point Russ, although the picture I saw of the 130SLT seemed to have a 2" focusser

It's not 100% clear from the picture on First Light Optic's web site:

SLT Series - Celestron NexStar 130 SLT

Definately worth checking before you buy any 2" eyepieces !

[Mr Spock]

The Celestron website says compatible with 2" eyepieces.

[russ]

hehe i quickly changed my reply as i realised the 130SLT was 2" compaitble.

But at f5 the 30mm 80deg will still be a very poor performer.

[John]

hehe i quickly changed my reply as i realised the 130SLT was 2" compaitble.

But at f5 the 30mm 80deg will still be a very poor performer.

I had to check that Russ - it quite surprised me as well

[michael.h.f.wilkinson]

At F/5 a 30mm yields a 6mm exit pupil, which is fine for people younger than 35, but above that a 25mm is better. You could go for a Nagler (after winning a lottery;))

[callisto]

At F/5 a 30mm yields a 6mm exit pupil, which is fine for people younger than 35, but above that a 25mm is better. You could go for a Nagler (after winning a lottery;))

Indeed, unless you win the lottery and can afford all those TV's,

most people will have to put up with astigmatism in eyepieces within that price range

[michael.h.f.wilkinson]

You could go for something like a hyperion.

[sixela]

Personally, the minimum I could stand is the equivalent of the Panaview (though I've only used Teleskop Service siblings).

A notch better are reincarnations of the TMB Paragon (which Kunming United Optics is selling through lots of channels, including Skywatcher) aka Skywatcher Aero ED, and Meade 5000 SWAs (which are available pretty cheap as they're discontinuing the line; search for "wide fishes" on Telescope experts Astroshop).

Above those you only have the premium eyepiece segment: Vixen LVW, TeleVue Panoptics, Pentax XW,...

One pretty good "sleeper" eyepiece if you can find one is the 30mm Vixen LV, with 60° AFOV. It's the odd man out in the series (almost a wide field) and that's why everyone forgets about it.