Eyepiece advice......

[Astro_Baby]

I am toying with the idea of a new EP. I dont really need it all that bad but its part of a non-smoking strategy.

Anyway what I want is a nice wide FOV low power EP to plug into the Sky-Watcher 200 f/5

I looked at the Moonfish 30mm Ultrawide 80° 2" Eyepiece - Enhanced but it says its doesnt perform well in scopes faster than f/6 - I suspect this is the same EP as the Sky-Watcher

Ultra Wide Angle (UWA) 2" Eyepieces as they look eerily the same.

I assume the problems in fast scopes are down to the FOV rather than the focal length of the EP.

I already have the Sky-Watcher SWA Panaview EP in 35mm and its great but I was wondering if an ever wider FOV would be better. Obviously if a fast scope cant hack it with wider then I suppose I'll look at something else.

Any advice on this one appreciated - at the moment its a kite flying exercise and I wont be buying for at least 60 days anyway.

Oh by the way I dont want to go much over around £100

[GazOC]

At f5 you can have any two out of "good", "wide" and "cheap"....;O)

[Whippy]

To my knowledge, the problem is with faster scopes is the steepness of the light cone. The faster the scope, the steeper the cone and the more the eyepiece has to 'work' to give a aberration-free view hence, the cheaper EP's work well in SCT's and Mak-Casses while have trouble in fast newts.

For me, Baader Hyperions work well enough in the 8" f5 newts although the aspherics are a touch over your budget.

Tony..

[John]

You get to a point where the focal length of the eyepiece gets longer but you don't see any more sky because the field of view is restricted by the barrel diameter. I have tried a couple of 50mm 2" eyepieces which worked fine with an 8" F/10 SCT but the exit pupil would be way oversize in an F/5 scope at 10mm - you may well have problems with eye positioning, black outs (not you - the eyepiece !) and seeing the shadow of the secondary.

Tele Vue were smart when they designed the Nagler 31mm of course - optimum focal length for F/5 scopes while maintaining a useable exit pupil (6.2mm) an ultra-wide FOV and sharpness just about right across - but of course you pay handsomely for such a combination. The UWAN 28mm comes pretty close though - but still not cheap !

TBH I reckon the Panaview is probably the best bet unless you want to throw a lot more cash at it.

John

[Astro_Baby]

Well the 38mm is fine for me - at 68' view ( stated ) it works well. I never see the secondary shadow except using the scope in daylight - I can see it if I try to see it - if you know what I mean. The rest of the time its invisible to me.

Maybe my pupils are very good - I dont know.

Anyway it seems like this is either going to be spend a ton on a Televue Nagler ( not practical for the purposes for which I am buying it really ) or buy another Panaview in 32mm.

I actually like the Panaview I have - it has a nice eyerelief, the view had a high contrast so perhaps a 32mm one of those is as good as its going to get.

Thanks guys

[John]

The Skywatcher Aero ED 30mm is nice - good light transmission and very comfortable to use.

John

[Andrew*]

John's suggestion of the 30mm Aero is probably an excellent bet.

But I would question your need for another wide field eyepiece.

The 38mm PanaView gives almost as wide a FOV as a 2" eyepiece (any eyepiece, in other words) can handle, and an impressively wide 2.6° field (26x), which will fit in almost any target up there.

A 30mm eyepiece will offer a 2° field at 33x - hardly different from the 38mm and still wide enough to encompass most targets. Certainly when I owned two wide field eyepieces at one point, I quickly picked my favourite and the other one never saw use and was soon sold.

I would personally recommend your next higher power up to be between 20 and 25mm (40-50x) for general DSO use. In the "superwide" (~70°) catagory, under £100, you don't actually have many options:

24mm Hyperion

26mm PanaView

21mm Stratus (Like a Hyperion, but really does have 68° field unlike 21mm Hyperion)

For a bit more you have also the options of 24mm Panoptic (brilliant), 22mm Vixen LVW. For a bit less you will be restricted to 60° or under - the 20mm or 26mm Meade S5000 Plossls are fine.

I hope you don't find my advice annoying or patronising. It's just what I would do. Only you really know what you want!!

Andrew

[John]

But I would question your need for another wide field eyepiece.

I think AB is contemplating this as a sort of "retail therapy" Andrew !.

I've done this sort of thing as well - I my case promising myself a nice eyepiece if I loose some weight. Trouble is I have given myself "advance credit" to the tune of 6 Naglers and an Ethos - I've just got to find a way to loose 35 stone now ........

John

[Kai]

Mel

Are you coming along to SGL4 ???

If so im sure there will be plenty of eyepieces to try out ,I have a 24mm Hyperion that you are welcome to play with.

[FLO]

Are you coming along to SGL4 ???

If so im sure there will be plenty of eyepieces to try out...

Definitely

[TheThing]

I have a 2" 40mm Erfle, 6 element - none the less - which I have found perfectly fine in my f4.9 refractor. Nice eye relief and no black outs.

Best bet is to try them and see.

[Andrew*]

Oh, I see. :

Anyway, if you're after one anyway, this is a great deal: http://www.astrobuysell.com/uk/propview.php?view=23415

Andrew

[Astro_Baby]

Andrew - no offence at all - happy to listen to advice and input or else I wouldnt ask. Dont see any reason why I would think your comments were patronising at all - I appreciate the input and help.

Yes its a kind of retail therapy - I am trying to quit smoking so I promised myself if I could stop I'd treat myself with the cash I saved. I did this recently and the idea fell over because I just stacked the cash away and it just went on bills and stuff and as a result, with no apparent benefits, I just lapsed.

I could set a high target like a Televue Nagler but the problem with that is the target would be so big it would be so long saving for it I just know I'd lapse again. When setting a target for anthing I always bear in mind the phrase 'by the inch its a cinch but by the yard its hard" - ie do things in small steps or else it becomes overwhelming.

John - I know that feeling about having spent so much that you cant possibly honor the promises you made to yourself and I have a stack of designer handbags to prove it LOL - been there before.

Anyway - back to EPs. I do take the point about the 38mm Panaview being (maybe) as good as its gets. Certainly the views through it are quite magical but I kind of wondered if a smaller EP - say 30mm may produce better results. I never see the secondary obstruction in the 38mm but I wondered if it may be there messing up the view and the view may be 'clearer' with a 30mm.

Theres a 26mm Rigel EP for sale on here as well with an 80' FOV and if that were still around in say 30-60 days I could buy that. My bet is it will have sold by then so I am looking at alternatives.

The 26mm Panaview may be a good alternative - I like the eye relief on the 38mm and its a very comfy EP to use.

Thanks though for your replies - it all helps the thinking.

[Andrew*]

Andrew - no offence at all - happy to listen to advice and input or else I wouldnt ask. Dont see any reason why I would think your comments were patronising at all - I appreciate the input and help.

Okay, that's a relief!

I am trying to quit smoking

Well done - good luck. My brother's been smoking for around 8 years (27th bday today) and he's not smoked since Friday - touch wood!

Anyway - back to EPs. I do take the point about the 38mm Panaview being (maybe) as good as its gets. Certainly the views through it are quite magical but I kind of wondered if a smaller EP - say 30mm may produce better results. I never see the secondary obstruction in the 38mm but I wondered if it may be there messing up the view and the view may be 'clearer' with a 30mm.

I think you will find it gives a darker background sky and will probably be very slightly better on faint extended targets - but generally it will frame smaller targets better and you'll probably end up using it more.

The 26mm Panaview may be a good alternative - I like the eye relief on the 38mm and its a very comfy EP to use.

The 26mm is up there with the 38mm in terms of comfort and eye relief, but I didn't find it quite as good optically, but at least it's cheap!

Andrew