Which widefield eyepiece?

[Hobbes]

I'm looking at upgrading my widefield eyepiece - currently a Baader Aspheric 31mm and am looking at either a TV Nagler 31mm or an ES 100 25mm.

The scopes I'll be using are an Orion Optics VX10 f4.8 and a TAL 125R f7.5

Running the specs through a calculator gives the following results:

Orion Optics VX10 + Televue Nagler 31mm

Focal Length:  1200mm  

Magnification: 39x

True Field of View: 2.1° 

Exit Pupil: 6.5 mm

Theoretical Resolving Power: 0.46 arcseconds

Approximate Limiting Magnitude of Telescope: +13

Orion Optics VX10 + Explore Scientific 100 25mm

Focal Length:  1200mm  

Magnification: 48x

True Field of View: 2.1° 

Exit Pupil: 5.2 mm

Theoretical Resolving Power: 0.46 arcseconds

Approximate Limiting Magnitude of Telescope: +13.2

Tal 125R + Televue Nagler 31mm

Focal Length:  940mm  

Magnification: 30x

True Field of View: 2.7° 

Exit Pupil: 4.1 mm

Theoretical Resolving Power: 0.93 arcseconds

Approximate Limiting Magnitude of Telescope: +11.9

Tal 125R +  Explore Scientific 100 25mm

Focal Length:  940mm  

Magnification: 38x

True Field of View: 2.7° 

Exit Pupil: 3.3 mm

Theoretical Resolving Power: 0.93 arcseconds

Approximate Limiting Magnitude of Telescope: +12.2

Both are a similar cost so on paper the ES 100 25mm looks to be a better bet particularly as I'm now on the wrong side of 50 and pupil size is getting to be an increasingly limiting factor.

Has anyone out there got real world experience of these eyepieces particularly the ES100 25mm that they could share?

[Tinker1947]

I would go for the Nagler, but that just me, would it be better than the ES i would expect so, but my old eyes may not see any difference....younger people might though...

[YKSE]

I agree, of the two, I would go for the 31 Nagler too.

I'm on the wrong side of 50 too, but had no problem in using 32mm plossl in my first f5 SW explorer 130P, even the sky were slightly bright. John (the mod, same side of 50) had used 32mm plossl in the f5.3 dob in backyard to get over 60 galaxies in one night, IIRC.

If you're very concerned about exit pupil, a 26mm Nagler can be a alternative.

[John]

I had an Aspheric for a short while - no good at all in scopes faster than around F/7, very "messy" in the outer parts of the field as I expect you have found.

I'm unconvinced by the ES 25mm / 100 in fast scopes from the reports I've read on it.

The Nagler 31mm is a killer and I used to use mine in scopes just like yours. The ES 20mm / 100 is also really nice and I had one of those alongside the Nagler 31 until I splashed out on an Ethos 21mm.

Other options:

ES 30mm / 82 degree

UWAN / Nirvana 28mm / 82 degree

Nagler 26mm (might be better than the 31 if you have light pollution to contend with)

There are probably others too but they have slipped my mind

[John]

....Has anyone out there got real world experience of these eyepieces particularly the ES100 25mm that they could share?

Here is some feedback from the most recent purchase of the ES 100 / 25 that I know of:

http://stargazerslounge.com/topic/250267-explore-scientific-24mm-68deg-bargain/?p=2744038

The eyepiece gets mentioned a few times in that long thread and there are some links in there to other reports on it as well.

[michael.h.f.wilkinson]

I love must say I absolutely love my Nagler 31T5, affectionately known to me as the Panzerfaust. I have used it in scopes as fast as F/4.2 or so, and it gave stunning views of M101, despite the large exit pupil (a 20" Dob on a dark site is just brilliant ). Haven't any experience with the 25mm 100 deg, which doesn't have enough eye relief for me.

[Hobbes]

Thanks All

I guess it's going to be the Nagler then.

[Mrbloke]

Even as an ES devotee, I would say Nalger on this one. Although I would argue it's not quite the same price!

On offer at the widescreen centre for £476 at the moment...

[seo]

+ 1 for the 31 Nagler.

[Sporadic Dobstronomer]

With Guildford not being the darkest of places, are you sure your eye will ever open up to 6.5mm    If not then the 26mm Nagler might be a safer choice.  I have one and it goes well with my f/4.5 Dob.

One possibility is that you could measure your pupil, eg by looking through a piece of foil with pairs of holes, before taking the plunge...

[Hobbes]

With Guildford not being the darkest of places, are you sure your eye will ever open up to 6.5mm    If not then the 26mm Nagler might be a safer choice.  I have one and it goes well with my f/4.5 Dob.

One possibility is that you could measure your pupil, eg by looking through a piece of foil with pairs of holes, before taking the plunge...

Probably not although we have a pretty decent dark site nearby and as I live right on the edge of Guildford up near Newlands Corner it is reasonably dark in my garden. Where it will really come into it's own is at star parties.

[TheUKDave]

I was going to post a topic just now which was going to be titled the same as this.  So if the OP has had their answer, hopefully they wont mind me hijacking the thread to ask the same question, but with some different options

I'm using just the one scope, SW 100 ED (900mm f/9).  And I'm looking at some ES eyepieces, and given that my current widest field eyepiece is the 28mm (I think it's around 56°) that came with the scope, and I'm hoping to achieve a wider field than that, to get the best possible views of things like Pleiades, Andromeda, and also just as a general finder eyepiece.  I'm wondering which of the following 2 main options people would recommend:

ES 68° 40mm

Magnification: 22.5x

True Field of View: 3.0° 

Exit Pupil: 4.4 mm

Cost: ~£210

ES 82° 30mm

Magnification: 30x

True Field of View: 2.7° 

Exit Pupil: 3.3 mm

Cost: ~£230

Both have similar true fields, close to the maximum for a 2" diagonal, and I gather that the larger exit pupil should make the 40mm a 'brighter' (??) eyepiece, and therefore better as a finder or viewer of fainter objects.  Is that standard wisdom, or is that debatable?

I'm also considering the ES 68° 34mm, since I've heard some good things said about it and it's cheaper at around £175.   There's even a Televue 55mm Plossl, which would still give a sensible exit pupil of 6.1mm.  But I for some reason I'm leaning towards the 2 above ones.  There'sI'll point out that the 31mm Nagler would be my ideal eyepiece, but ... that's almost 3 times the price of any of the above.

Oh, and finally, I think I've decided that in the nearish future, I hope to own the ES 100° 20mm, and then the 14mm eyepieces.  But for the immediate future, I'd like to get the far end of my eyepiece collection started.

Cheers,

Dave

[Mrbloke]

Just to mess your plans up, I bought the ES 100 20mm from the display items sale here

http://www.bresser.de/en/Sale/Display-Items/0218420-1.html

Uber bargain. The scope spends 95% of its time with this eyepiece in and I love it. It's also used as my finder eyepiece, but is so good it stays in there.

[John]

Hi Dave,

No problem about the post above but you might get more replies if you start your own thread

I owned an ED100 quite a few years back and I've got an ED120 now. Nice scopes

You might find that objects actually seem a little brighter with the 30mm because it's higher magnification darkens the background sky more than the 40mm will. They are not really any brighter but the background sky is darker.

The 20mm / 100 ES linked to above is superb and does even more for a dark background sky.

In reality, I feel that sacrificing a little ultimate field width for darker sky background is good trade. 

These are all heavy things though - make sure your diagonal and focuser are up to the job

[TheUKDave]

Wow, that really is a good deal.  I've been looking at the same piece for a couple of weeks now on OPT (a US company) which has it for only $300 brand new - even cheaper than your link!

I've been waiting for a friend (or colleague) to go to the US so I get them to bring me one back with shipping and VAT and import duty, it'd wind up being about £300, which is still a bargain, but just less of one.

I actually may well end up getting it from that site actually.  But I think I would like it in addition to the eyepieces I was originally talking about, I'm still interested in a 30+mm eyepiece for larger DSOs and/or for DSO-hunting.

Cheers,

Dave

[John]

I might be tempted to go for the 40mm 68 as your scanning / finding / widest field eyepiece AND the 20mm / 100 to examine them with

Choices, choices ....

My ED120 has the same focal length as your ED100 and I find both my Nagler 31 and Ethos 21 pretty useful with it although the latter gets more use than the former.

[YKSE]

Dave,

Of your 4 choices (30mm 82°, 34mm 68°, 40mm 68° and 55mm plossl) for your 100ED, I would pick the 40mm, together with your coming 100° 20mm and 14mm, it should be a very good combination.

Comparing the 20mm and 40mm should be fun, with an OIII filter in a dark site, you can check e.g. Veil nebula now or Monkey head nebula (NGC2174) later in the season, you will noticed how the size of exit pupil play roles.

[TheUKDave]

Thanks for that John and YKSE, I think it's kinda the answer I wanted to hear

But just because I'm fickle, and because that is a stonking deal on the ES 100° 20mm eyepiece, I've taken a slightly different tactic.  I'm going to grab the 20mm eyepiece, and also, I heard some good things about the Skywatcher 38mm panaview eyepiece, so I've got that on order too.

Being that the panaview is about 1/2-1/3 the price of the ES eyepieces, it's a less considered purchase.  And since it gives an almost identical TFOV as the ES 40mm I was looking at, I might pick up the ES eyepiece later on, compare the 2, and sell on one of them

Cheers,

Dave

[John]

The Panaview will be good in your F/7.5 refractor. The field edges won't bt too pretty at F/4.8 though - the ES 20 / 100 will probably show a larger sharp field. 

[wasteland]

Just to mess your plans up, I bought the ES 100 20mm from the display items sale here

http://www.bresser.de/en/Sale/Display-Items/0218420-1.html

Uber bargain. The scope spends 95% of its time with this eyepiece in and I love it. It's also used as my finder eyepiece, but is so good it stays in there.

Damnit, I knew bad (good?) things would have happened had I clicked on that site. I ended up getting a 68° Maxivision 20mm for just 55€, to replace my supplied Orion Sirius 25mm. It may have been a bargain

[Tinker1947]

FLO have tihis EP on the clearance section.......

http://www.firstlightoptics.com/clearance/clearance_explore-scientific-82-degree-series-eyepieces_44127.html

[Hobbes]

Quick update on the eyepiece choice.

I was all set to buy the Nagler 31mm but had to wait as it was out of stock at the Widescreen Centre when Telescope House threw a spanner in the works by dropping the price of the ES 100 25mm from £582 to £425. (its now back up to £582 and they are out of stock) so I risked it and went for the ES 100 25mm. Just waiting for a clear night now to try the beast out!

[John]

I'll be interested to hear what you make of the ES 25 / 100 Rob. There was a thread on here recently which seemed a bit inconclusive but not many folks own / have tried one so that might be why !

Edit: I can see that some of that discussion was covered earlier in this thread so that won't be news to you

[F15Rules]

I have the ES 34mm 68 as my finder ep and it's actually my favourite eyepiece. I:m sure the 40mm is also great but in semi urban skies the 34 mm gives a nice dark background I find.

Dave