EP for nebulas/galaxies

[cpper]

Since DSO's are my main goal, I'm interested in a good quality, mid-power(14mm to 20mm), wide field eyepiece for watching galaxies and nebulas, to use with the Skywatcher 6" f/8 dob I will buy. I don't think I need a very big eye relief because I don't wear glasses.

This are the EP's I can choose from. I googled a bit each of them and found mostly good reviews. I made a little table: 

Name  Focal length  aFOV  tFOV  Exit pupil   Price  Celestron X-Cel LX 18mm 60° 0.90° 2.29mm 60$ Meade Series 5000 HD-60 18mm 60° 0.90° 2.29mm 80$ Celestron Luminos Series 15mm 82° 1.03° 1.91mm 95$ Orion Edge-On Flat Field 19mm 65° 1.03° 2.41mm 100$ Orion Epic II ED 18mm 60° 0.90° 2.29mm 100$ Celestron Ultima LX Series 17mm 70° 0.99° 2.16mm 100$ Orion Epic II ED 15mm 60° 0.75° 1.91mm 100$ Orion Edge-On Flat Field 16mm 60° 0.80° 2.03mm 105$ Meade Series 5000 UWA 14mm 82° 0.96° 1.78mm 130$ Explore Scientific 14mm 82° 0.96° 1.78mm 140$ Orion Stratus  17mm 68° 0.96° 2.16mm 140$ Explore Scientific 16mm 68° 0.91° 2.03mm 140$ Baader Planetarium 17mm 68° 0.96° 2.16mm 140$

I would not buy one of the most expensive ones, just if it's really really better than cheaper ones.

Of course the Celestron Luminos sounds the best, I checked many reviews and found out it's highly noted, but I want to hear your opinion too, if possible. 

[cpper]

Here is the table, no edit post option:

[Daniel-K]

youve missed ES 18MM 82 deg ive been using this for a while to tracking faint fuzzies

[Chris]

The ES Maxvision 20mm 68 degree springs to mind, you wont beat it for the money

Chris

[John]

A Tele Vue 20mm plossl has a standard field of view but has higher % light transmission than most eyepieces. Just as an alternative

[mdstuart]

I use an x cel lx 12mm for galaxy hunting and I would say it has great transmission for faint galaxies compared to many eyepieces so I would go with that if you do not want a 80 or 100 deg view..

Or go for the plossl as John says...less glass = more light through from those fuzzy blobs..

Mark

[YKSE]

Just to make it more difficult for OP,  18mm Baader Classic Ortho gets my vote, 50 deg FOV if wider FOV is a must for you. Optically, its on axis performances is at least as good as the best EPs in your table, if not better.

[Moonshane]

one option if you can find one is a used 16mm type 2 nagler. these go for maybe £100. I have recently started sketching with my 12" f4 dob (same focal length) and there's plenty of space around almost all galaxies with even a 15mm plossl in this focal length. I also use Televue.

to give an idea of the sort of space around galaxies here's a sketch at this magnification (about 80x)

[John]

Just to make it more difficult for OP,  18mm Baader Classic Ortho gets my vote, 50 deg FOV if wider FOV is a must for you. Optically, its on axis performances is at least as good as the best EPs in your table, if not better.

Thats another that would be on my list. 

[rwilkey]

Avoid the Baader Hyperion 17mm, that can be a bit soft on fast Newts, my personal choice would be the ES82 Series 14mm, a great ep and a choice I have already made.

[cpper]

Thanks all

I decided I want to stay with a 82° EP, because I really like the idea of a almost unlimited view

The three to choose are these:

Celestron Luminos 15mm

Explore Scientific 14mm

Meade 5000 14mm

Any advice ? 

[bingevader]

I have the 14mm Meade 5000 UWA and it's lovely in my 'scope, good sharp image. 

[SteveB72]

Thanks for this discussion I have been asking myself the same question.

I was wondering how the 82deg EP's would work in my 400P which is about F4.45 (1800mm/405mm), I am concerned about excessive coma then wishing I have bought a narrower FOV EP.

I would be grateful for your thoughts.

Thanks

[scarp15]

For some galaxies and certainly for Planetary nebula I typically use a 10mm (x160), 9mm (x178), 7mm (x229)

The 10mm is 72 degrees the 9mm and 7mm 82 degrees. I do not notice coma in these eyepieces with my F4.6 scope. Personally i do not find coma to be so bothersome and only slightly notice it in my 26mm nagler. If I was to go with a coma corrector, then my personal choice would be for a baader MPCC MKIII, optimized for F4.5 scopes but will work down to F3.5. This corrector will retain the focal ratio (thus magnification) as it would only get used in the 26mm. So at a higher magnification with well corrected eyepieces, coma is less of an issue. However between F5 and F4.5 requiring a coma corrector for any eyepiece is very much a personal choice, becoming much more of a requirement I would expect from F4 and faster.   

[jetstream]

Another vote for the 18mm BCO,extremely good,comparing to much more expensive glass (my Ethos 17) with a smaller FOV.I have both.Thanks to John and YKSE for pointing them out to me (us)

[John]

Thanks for this discussion I have been asking myself the same question.

I was wondering how the 82deg EP's would work in my 400P which is about F4.45 (1800mm/405mm), I am concerned about excessive coma then wishing I have bought a narrower FOV EP.

I would be grateful for your thoughts.

Thanks

I think you ought to be seriously considering a coma corrector if investing in well corrected 82 degree eyepieces for use in an F/4.45 newtonian. 

[AlexB67]

my personal choice would be for a baader MPCC MKIII, optimized for F4.5 scopes but will work down to F3.5. This corrector will retain the focal ratio (thus magnification) as it would only get used in the 26mm. So at a higher magnification with well corrected eyepieces, coma is less of an issue. However between F5 and F4.5 requiring a coma corrector for any eyepiece is very much a personal choice, becoming much more of a requirement I would expect from F4 and faster.   

If you use the CC for a lower power eyepieces or two this would be a very good option I believe.

I recall one chap doing just that, he screwed the exension rings onto the eyepiece to tune it into the coma corrector and only use it with his lowest power eyepiece, nothing else.  The whole lot just went into the 2 inch eyepiece as if it were one item. So just as changing an single eyepiece item there was no hassle adding removing tuning rings. You could actually do that for all eyepieces but if you have Joves collection that would cost a lot in extension rings for  minimum hassle, enough to buy you several paracorrs 

The biggest benefit of the MK3 is that it retains the f ratio as you say, and for many, if you used a paracorr, or one of the cheaper alternatives like the altair astro  that magnifation factor would change a 30 mm eyepiece into a 26mm. Not acceptable for some.  it also turns into a nice light weight alternative, the MPCC Mk 3 is light, less glass and the transmission is allegedly rated to be superb and close to 98% ( wave length unspecified ).

That being said, without going offtopic and the pros and cons of coma corrector designs, If as an allrounder coma corrector I would favour the altair astro design for a budget solution, weight aside. The 4 element design and the magnification factor that comes with coma correctors are there for a good reason, or so as I understand it to allow them to work optimally in order to keep a as good and well corrected field as possible, it also allows flattening of the field a bit and reduce field curvature and therefore work better allround. Thr design excells better at higher magnifications too ( if you use them for that ).

In theory anyway all this applies, but the differences could be very small not to worry about the tradeoff in most cases. As I understand It however that 1x magnification factor does come at a penalty, though not sure what approach or exact design the MK3 uses, there is some debate over that, though there are generally  plenty happy users. 

There is some good info on the telescope-optics.net on the various designs, pros and cons etc. From what I read, for visual use I would favour a paracorr like design that works on the same principle. The best cheap cost alternative I am aware of that fits that  bill is the altair astro one. The ES is also now for sale, but little is known about its performance to date, also it is not cheap, but no doubt it will be very good also. 

I've been reading around on this topic quite a bit in preparation, since I intend to buy one after a couple more eyepieces.  Ultimately, I decided that for me the paracorr is the one, ideally a second paracorr 1, or perhaps the ES, mainly because of the tuneable top for use with several eyepieces. I just want it to be as hassle free and as convenient possible in the long run. Personally I am quite happy to save and pay for that a later date.  No rush at 68 degrees I find coma not be a hassle in my scope, sure, it is there and it would be nicer with correction but no biggy . If I had 82 degree eyepieces  and at lower power it would begin to annoy me enough though, and I'd want one sooner than later

[Caldwell14]

A Tele Vue 20mm plossl has a standard field of view but has higher % light transmission than most eyepieces. Just as an alternative

A Tele Vue 20mm plossl has a standard field of view but has higher % light transmission than most eyepieces. Just as an alternative

Indeed. You could do worse than a 32mm TeleVue Plossl for extended objects such as M31, 33, 45 BTW