recommendation for eyepiece between 42mm and 22mm

[jeelan]

i've spent the last few nights in Perth doing a lot of DSO gazing and found myself predominantly using my LVW 42mm and Pentax XW 20mm the most.

Occasionally i changed out to the LVW 17mm but that was fairly infrequent.

I find myself enjoying the 42mm - 20mm range the most at the moment, so my question is, what would you recommend around the 30mm size for an additional eyepiece?

FYI - i really like the darker background and contrast of the XW eyepieces, however the viewing comfort of the Vixen LVW is just sublime.

Ideally I want something that shares both those characteristics :):) Probably something that will give me around 100x magnification (scope is 2800mm f/l).

any suggestions?

cheers
Jeelan

[Kunama]

Panoptic 27 ? Similar eye relief, AFOV to the LVWs and XWs.

Nagler31? Wider AFOV, nice eye relief but quite a heavy beastie.

[jeelan]

Thanks Matt,

i've been reading up on the Panoptic v Nagler and leaning towards the Pano at the moment.

How do the ES pieces in this category fit? comparable in IQ?

cheers
Jeelan

[janoskiss]

The Pano may look similar in terms of specs but it's a different beast to the LVW or the XW (which are more similar to each other, though I have not used the 42mm LVW). IIRC the panos have more pincushion distortion and a slightly warmer colour tone. That's not a bad thing, just different. (Pincushion is much preferable to barrel distortion btw, for reasons ... ;))

With a long f-ratio scope you have a lot more options than us dobbers. But the Nagler 31mm T5 is still the undisputed champ around that focal length. I prefer the 30mm XW though, but it's no longer available. Maybe ES 30mm ultra-wide??? (never tried one but a lot of folk seem to like it)

You could also just get a 30mm Superview (because it's cheap and will do all right in your scope) just to see if that focal length really suits your observing habits. Sometimes you think you should "fill a gap" only to find it does not need filling IME.

[Kunama]

I know nothing about the ES range, have never owned one, but others seem to find them suitable. I have the N31T5 and the N22T4 as well as the XW20. I find they suit my Dob ( Focal length of 2550mm)

[jeelan]

I've got a couple of WANTED ads floating around for a XW 30 but i'm guessing i'll have more luck getting water from a rock :-)

I'll have to see if anyone i know has a Nagler 31 to have a look through it.

cheers
Jeelan

[MortonH]

The ES68 28mm would be a good option at the cheaper end of the scale.

[clive milne]

I'm assuming this is for a C11?
In which case the Nag 31 is highly recommended.

[Wavytone]

Well... to state the obvious there is an LVW42mm, and I have one ;) as the eye relief is important to me (specs), and IMHO I don't value the ultra wide fields of views particularly in low power eyepieces. There is something to be said for having a black field stop limiting the apparent field of view and maximising your dark adaption.

The Nagler, Panoptic or ES 30mm 82 degree are alternatives.

However: in my scope the LVW42 appears be pretty much uniform optically across the whole field, i.e. pinpoint, no ghosts, no odd reflections.

The ES30/82 is pretty good but has less eye relief. Most of the field is flat and sharp but the outermost 10% shows lateral chromatic error and with bright objects near the edge there is a nasty internal reflection off the inside of the draw tube. One downside of this eyepiece is that it is a real monster the size of a house brick - 1kg - and enough to possibly upset the balance of a C11.

Naglers and Pans... very good as one would expect if you want to pay that much, however the eye relief is again much shorter than the LVW42.

[jeelan]

hey Wavy,

I'm trying to plug the gap between the my 42mm and the LVW22mm/XW 20mm.

however the comment from JANOSKISS has given me some pause: "Sometimes you think you should "fill a gap" only to find it does not need filling IME."

that being said, i dont have issue considering the N31 except for weight and weight shouldn't bother me on the C11, it'll handle it so i'm just waiting for an opportunity to try/look through this one and the Panoptic before making a decision.

cheers
Jeelan

[N1]

+1
That, or a 32PL. The TV example might just be good enough to be a permanent fixture if you can handle the limited AFOV.

[janoskiss]

If you find either of those in good nick second hand and you look after it, then it's like a free or postage-cost rental (should you change your mind) because they hold their resale value very well. Same goes for most premo or even a notch below premo EPs. But checking them out first if you can is a good idea in any case. Good luck solving your zeroth world problem. :P :lol:

[janoskiss]

PS. you could also just go fpr a 20ish mm ultra- (80-deg) or hyper- (100-deg) wide, e.g., Nagler 22mm T4 or Ethos 21mm, or one of their cloned or inspired equivalents from another manufacturer ...

From Televue, the first EP that really impressed me was the 13mm Ethos. The 21mm Ethos has (amongst friends) the same FOV as the 26mm T5 Nagler and will mop the floor with the 27mm Pano. It's a more modern design as well, from lenses to coatings, geometric distortion and colour balance... I like the Ethos' a lot but you have to see for yourself if 100-degree FOV is really practical and note that I am merely expressing a personal opinion here: my eyes, my optic nerves, my brains. aka YMMV.

[casstony]

To my eye the views through an ES 30mm and Nagler 31 are identical in a C11. The ES 28mm is also a very nice eyepiece.

The ES 40mm and Pan 41 are also very close in a C11 with the Pan showing slightly less aberrated stars in the outer field. On axis they're identical.

[Wavytone]

Jeelan,

I found I was usually using either LV50 or LVW42 as the lowest power then switching to 22 or 13mm.

When assembling my set I had originally bought a couple of 30mm eyepieces (NLVW and a TMB Paragon) but rapidly found them pointless and sold them.

Personally I wouldn't bother with a 17mm either, its too close to 13mm or 22mm.

IMHO you really only need 3 eyepieces:

a) lowest power your scope can handle (basically a field stop as big as you can get in the barrel)

b) a medium power about 1X per mm of aperture, this equates to an eyepiece with a focal length in mm equal to the focal ratio of your scope, or a tad less; this will be the one you use most when the seeing is average to poor;

c) a high power about 1.5X per mm of aperture, you might use this occasionally when seeing is really steady.

[janoskiss]

@Wavytone sorry to be blunt but your advice on EP selection (3 EPs, abc) is terrible. I can't be bothered explaining why (it's late and I'm out of energy) but maybe others can chip in. Or just think about it for a minute.

[The Mekon]

Agree with you here Steve. Wavytone's eyepieces would have my 18" give magnifications of 60x 450x and 675x

Strange, as I usually find his posts very informative.

[Kunama]

Looking at the calculator, the Nagler 26 actually fits well between the LVW42 and the XW20 almost halfway in fact. 106x , TFOV 0.759 degrees, 2.59mm exit pupil and a field transit time at zero DEC of 3 minutes.

[janoskiss]

Never look at "the calculator"! :scared: ;) I assume it's based on a geometric progression, which is a big improvement over a linear scale based on EP FL or magnification (that some lesser manufacturers go for). But our eyes and brains don't work that way. We need one or at most two wide-fields and more options for the close-up tease-out-detail stuff. (Actually the "calculator", if it works how I think it does, can help with the latter.)

Nevertheless, uncle Nagler's T5 26mm would indeed also be a very good choice with less hand grenade factor than the 31mm.

[Kunama]

Here is the calculator I use:

http://www.stargazing.net/naa/scopemath.htm

enjoy it Steve !!! :eyepop::scared:

[janoskiss]

@Kunama (Matt) That's more basic than I imagined. I foolishly assumed it recommended a set of EPs for a given scope. :P My bad. :nerd:

[Kunama]

It is actually quite handy for quick comparisons of TFOV, Exit Pupil, and transit times. I doubt there is a program that I would allow to override my bone encased computer in choosing the actual eyepieces. We all have such different wants, tastes and especially eyesights that we still have to make the final decisions ourselves.

I use the:
Research it
Buy it
Try it
Critique it
and
Keep it or Sell it

:lol:protocol in my selection......

[janoskiss]

Have no doubt because your bone encased master is the one you're trying to please. ;)

Not to sound like a TeleVue fanboi (which I'm not; they're fine and dandy just mostly don't suit me), but forgetting about the brand, TV have some great sensible advice on their website re EP selection for any scope: linky (http://televue.com/engine/TV3b_page.asp?id=154&plain=TRUE#Eyepieces)

[wavelandscott]

I concur that reading some of the material written by Al Nagler and posted on the Telrvue website is time well spent.

I do have a mixed eyepiece case with some TV, Pentax and a few others (Denkmeir) regardless, I do agree with the mindset that Al Nagler espouses in terms of number and key considerations to keep in mind.

[Wavytone]

Well you've motivated me to explain. Having been a visual observer for 40+ years using scopes from f/3.7 to f/18, I well know the temptation to acquire a box full of eyepieces, having owned upwards of a dozen at times, the rationale being to have all bases covered. Which is bullcrap.

1. Some years ago three friends who were very active DSO observers ran an experiment to determine the optimal run for selecting eyepieces to observe smallish DSO's - mainly galaxies and planetary nebulae. They came up with X1 magnification per mm of aperture.

There is also a good basis for this from optometry - this correlates with a magnification such that the resolution of the scope (the Airy disk) on the retina is similar to the spacing of the rods in your retina used for low light vision. When you do the maths for the average eye this does indeed work out very close to a magnification of X1 per mm of aperture.

On bright objects (the planets) where some colour is visible more extreme magnification is desirable - and useful - due to the spacing of the colour-sensors in your retina (cones) being quite different to that of the rods.

2. Then there is a little matter called "seeing". On most nights at average locations seeing is rather better than 1 second of arc. You can figure for yourself what that means in terms of magnification, but again it leads to a very different result for dim objects where you're relying on your rods, vs the bright objects (planets) where colour is visible, and the cones come into play.

3. Most visual observers have a scope that handles a range of magnifications from lowest to highest around 1:4, this is a consequence of using very fast newtonians. Using factors of 2 you can cover that easily in just 3 eyepieces.

Even a range of 1:10 can be accomplished in just 4 or 5 eyepieces easily. But do you really need them all ?

4. I'll say NO. from a purely practical perspective I have no problems switching from a very low power wide field eyepiece (42 or 50mm) to say 13mm or even 8mm in one step.

Presumably you find this a bit hard and want to swap rather more eyepieces.

I don't, and I suggest you take a hard look at those you actually use often. My guess is there are just 3, and the rest don't matter.

[Kunama]

Interesting ideas Wavy, not sure I agree that one only needs to own three eyepieces. I find I usually only use three eyepiece in a session but the focal length and AFOV of those used in each session varies, I tend to look at the conditions and then select the scope I am going to use. Then depending on that choice I select eyepieces that I think will be suitable for that session.

You choices of LVW 42, 13 & 8 for instance would give me:

42mm .... 61x, exit pupil of 7.5mm and a true field of 64 arcmin
13mm ... 196x, exit pupil of 2.33mm and a true field of 19.9 arcmin
8mm ... 319x, exit pupil of 1.45mm and a true field of 12.2 arcmin

If I used your a.b.c. recommendations I would end up with

63x
457x
685x

That would be rather restrictive.

[casstony]

If you look at the OP's signature I don't think there's much point discussing having only 3 eyepieces. Maybe 3 eyepieces per telescope :)

[Kunama]

Quite true Tony, I think slotting an N31T5 into that lineup would do for a lifetime of observing.


(since when did threads stay on topic..... ;) )

[Camelopardalis]

I like to have options when I'm observing, but IMO there's little to gain between ~20mm and ~40mm with C11, it's just not a huge difference. For a different _experience_ maybe.

I find it's more useful to have options at the lower end of the focal lengths, so you can pick and choose the right tool for the job based on conditions.

[ausastronomer]

Hi Wavy,

I think you meant to say "worse" than 1 second of arc, not "better" than 1 second of arc.

Cheers,
John B

[jeelan]

I was going to note that but find the discussion interesting nonetheless so happy to follow along :-)

cheers
Jeelan

[Kunama]

That's what I like about these threads, the original question is usually answered in the first couple responses. There follows always an interesting discussion, on related aspects, that is a great learning resource.

Let us know what you decide. For me the 31mm Nagler was an obvious choice as it gave the largest true field without exceeding 82° apparent field. I find the 100° eyepieces annoying as I hate that 'peering around the corner' feel.

[Wavytone]

That's a good description of the problem, matt. More is not always better.

[Camelopardalis]

Luddites :poke:

[Don Pensack]

The 31mm Nagler will work for glasses as well, making it a logical intermediary between the 42mm and 20mm.
However, it is a bit wider apparent field than the others, so perhaps a 27mm Panooptic, with the same eye relief as the 31 Nagler would be a better choice.
Looking at the field stops might give us a clue:
42mm LVW 46.5mm
27mm Panoptic 30.5mm
20mm XW 24mm
The Panoptic is logically placed by field size.
Does it make sense from the standpoint of magnification on the C11?
42mm--67x
27mm--104x
20mm--140x
Yes, it makes sense there, too.
So the recommendation of the 27mm Panoptic was inspired.

Just one more thing: if you get a 31mm Nagler, the 42mm LVW will get used less and less and less until it just fades away.
I'm just sayin'.............

[janoskiss]

I agree. For sure it's one or the other since they have about the same AFOV. Anything else is polygamy which is illegal in this country and impractical in amateur astronomy. :P

[ausastronomer]

I own both the 31mm Nagler and the 27mm Panoptic. They are both very useable with eyeglasses on. Notwithstanding they both have a stated eye relief of about 19mm, I find the 27mm Panoptic to be slightly easier and a little more comfortable to use than the 31mm Nagler with my glasses on, but they are both pretty good in this regard. This is possibly due to the narrower AFOV of the Panoptic and its slightly different shaped eye lens housing and eye guard.



The 27mm Panoptic is an excellent eyepiece and in some circumstances is a better choice than the 31mm Nagler. For instance in my 10"/F5.3 dob it is my low power eyepiece of choice because it doesn't have the size and weight issues of the 31mm Nagler. It's a really nice compact lightweight package. A similar physical size to the 17mm Nagler but way lighter.



I couldn't agree more. You're 100% correct in that statement Don.

Cheers,
John B