best low power eyepiece

[qld]

;)what is the best low power eyepiece for a 25 inch f5 obsession and a 16inch f4.7 ,galaxy mirror obsession (made to order) with or without a paracor ,over 55 yrs and money is not a issue,when you get to that age as every night is a good night.

[wavelandscott]

Without a lot of consideration and thought I'd list the following that I have uses in no particular order...keeping in mind no expense is spared

Pentax XW 40 mm
Pentax XW 30 mm
Televue 31 mm T5 Nagler
Televue 35 mm Panoptic
Televue 21 mm Ethos

I own the Ethos and it is an amazing eyepiece...it is huge but quite something to look through!

[dannat]

i prefer to keep the expense down, edmund rke 28mm

[qld]

:lol:mate i use them for book ends

[AstroJunk]

That's easy, the 31 Nagler is the only low power eyepiece worthy of your scope.

I cheaped out and bought the 35 Panoptic and boy can you tell the difference!

For medium powers, buy anything with the word 'ethos' on it!

[HCR32]

31 Nagler
21 Ethos

period!

[Suzy]

Take a look at this thread- it is very informative (and not just about Naglers either). http://www.iceinspace.com.au/forum/showthread.php?t=16269

[Archy]

Interesting replies: but do those replying to Qld base their replies on actual experience with a 25 inch f5 Obsession?

[AstroJunk]

An f5 25" SDM, an f5 30" SDM, 2 x f5 20" SDM's and an f4.5 18" Obsession. Do they count?

[wavelandscott]

15, 18 and 20s only...assuming that they'll be similar

[Archy]

Yes

[jamespierce]

21mm ethos for my money, naglers sadly seem pedestrian to me now for wider fields.

[Archy]

an Ethos 21 will give 151 magnification: Do you consider that to be low power?

[JethroB76]

I think Scott has covered most the options.

Do you have a suggestion Archy?

[jamespierce]

Yes, the field of view is much of a muchness between a 31 nag, 35 pan and 21 ethos. Higher power with a wide field of view is an advantage increasing contrast and pulling out more detail.

[AstroJunk]

How true :rofl:

[Archy]

Is this is based on your personal experience with the eyepieces in an F5 25 inch scope?

[jamespierce]

Ok I'll bite, but this is the last time. Have I looked at those three eye pieces, side by side in a 25" F5 on the same night... no. Have I looked at all those eyepieces in a wide range of large fast scopes... yes. While the field will be slightly wider in the NAG or PAN options, the exit pupil is also getting huge, over 6mm for the NAG and over 7mm for the PAN, unless you have young, and perfectly dark adapted eyes you're just not going to be seeing all the photons. Anyway, enough numbers and conjecture on an internet forum, in reality any of those eyepieces is going to look great in a big scope like that, and we're all just talking about the last 10%.

[Archy]

Actual experience and numbers is what it is all about.

FYI the difference in FOV between the NAG31 and the ETH21 is 21%, which is not inconsequential.

At a dark site, where else for a 25" scope even old eyes can get to 6mm eye pupil, so a NAG31 is not out of the question, the power is lower and the FOV is broader so that the observer can see 46% more sky.

[qld]

it seems to me that in this forum televue low power eyepieces agree with every one ,and the type of tele vue chosen is largely a personal choice(BIT LIKE PICKING A SPORTS CAR) I was hopeing that other brands of eyepieces may have been nominated by experienced users and i invite those commentators to express their point of view as it may generate more knowledge and information for end users like myself, before this thread is dead buried and creamated thanks all

[wavelandscott]

I don't want to be overly jerky in my reply but your original post asked for a "best" recommendation and also stated that money was not an object...

With those two criteria in mind the response will be almost automatic with Televue (Ethos, Naglers, Panoptics) I suspect being the number one response in almost any Astro Forum you visit. Pentax also makes some "best" eyepieces that are compared favorably to the TV with some that prefer them (think dueling sports cars)...

In terms of actual field experience using the original criteria that is to my mind the complete list of commercially available options. Setting aside some Zeiss (and similar) hard to find collector eyepieces...I think you've been referred to the cream of the crop.

There is one potential addition to this list of "best" but as yet untried, the new Nikon widefield eyepieces (name escapes me)...I understand that they have just started shipping in the last week or so. I am not aware of anyone I know (and respect) who has tried one yet so the jury is out on them in my mind.

If you are interested in other options at different price points those recommendations can be made but you will necessarily not meet the criteria which was laid out in the original post...ie "best".

If you want alternatives to the "best" (or nearly best) then I might encourage you to start another thread seeking comments/suggestions on that topic. I would imagine in that thread that people might advocate the Explore Scientific and/or Williams Optics (and others) eyepieces. While many of them are quite good...they would I beleive not be deemed in the "best" category but would win in the "great value" or "bang for buck" category...

Clear Dark Skies to you!

[ausastronomer]

Hi Jonathan,

You obviously have not used a 30mm Pentax XW :) I have a 31mm Nagler myself on the basis that my goal at this focal length is to maximise the FOV, whilst retaining an exit pupil under 7mm. However, I am the first to concede the 30mm Pentax XW outperforms the 31mm Nagler in certain eyepiece performance criteria. Noting the differences aren't mind blowing.

1. It has better light throughput and contrast; and will go deeper and resolve slightly dimmer targets.

2. It is sharper on axis.

3. It has more "neutral" and "cooler" colour reproduction and coloured stars appear a little nicer.

3. It has more "useable" eye relief and is more comfortable to use.

4. Because of the eyecup/eyelens design there is a reduced tendency of the 30mm XW to "dew up" the eye lens.

5. It is smaller and lighter, which isn't a major concern with a large scope.

The advantages of the 31mm Nagler are, it is slightly better corrected at the EOF and it has a greater true field of view.

The decision is a long way from a "no brainer". It depends what you're looking for because the 30mm XW outdoes the 31mm Nagler in some criteria. If you plan to use a paracorr the 30mm Pentax XW is a better eyepiece in every respect, outside FOV, because the paracorr cleans the EOF up beautifully in the 30mm XW.

In an F5 scope I wouldn't be going any longer in focal length than the 35mm Panoptic, for an over 55yrs observer. That having been said the 35mm Panoptic IMO isn't nearly as good an eyepiece as the 31mm Nagler or the 30mm Pentax XW, so I would base your decision around those two.

Cheers,
John B

[ausastronomer]

Hi James,

Whilst your theory is correct, you need to consider the practicalities. Under poor seeing and rapidly falling temperatures a 21mm eyepiece is sometimes not useable in a 25" scope, particularly early in the night, while the mirror is settling. The images go to mush. There have been several nights we could only start with a 26mm Nagler in the 25" and 30" 3RF scopes.

In addition to that there are many open clusters which look much nicer at low power than they do at high power. With a 21mm ETHOS in a 25"/f5 scope your lowest power is 150X and a lot of clusters are fragmented at 150X. A classic example of this is NGC 4755 "The Jewel Box". At <120X it looks magnificent in a 25" scope, at 150X it barely resembles an open cluster because of the apparent separation of the stars.

Cheers,
John B

[jamespierce]

Yup, I do agree with you there John B - The 35mm Panoptic is a really nice eyepiece for some of the larger objects for just that reason... I'm spoilt with our APO nearly always setup next to our dob to take in the wider field views anyway.

[Archy]

From an old post by John B:

"Hi,

I own a 27mm TV Panoptic and a 31mm TV Nagler T5. I have also used the 30mm Pentax XW. Optically the 30mm Pentax XW is a class above the 27mm TV Panoptic, which itself is a very good eyepiece. Optically, I also rate the 30mm Pentax XW ahead of the 31mm Nagler T5. However, at this longer focal length my objective is to maximise the FOV, not contrast and light throughput (where the pentax excels).......

The 30mm Pentax XW is one of the very very best eyepieces money can buy, at any price. Highly recommended.

Cheers,
John B"

It seems to me, Qld, if by seeking to use low power eyepiece you are trying to get FOV, then it's the N31.

Some people on Cloudy nights report coma with Ethos 21, but not with the ES the Williams 28 or the Pentax 30 XW.

[AstroJunk]

I rest my case ;)

[Archy]

Scott's reply to "http://www.iceinspace.com.au/forum/../vbiis/images/buttons/viewpost.gif (http://www.iceinspace.com.au/forum/showthread.php?p=644238#post644238) Interesting replies: but do those replying to Qld base their replies on actual experience with a 25 inch f5 Obsession"

was "15, 18 and 20s only...assuming that they'll be similar"

That is, his opinion was not based on actual experience.

[Archy]

?? how does this square with what you said previously when in reponse to the post by jamespierce http://www.iceinspace.com.au/forum/../vbiis/images/buttons/viewpost.gif (http://www.iceinspace.com.au/forum/showthread.php?p=644911#post644911)
naglers sadly seem pedestrian to me now for wider fields.
you replied "How true."

[JethroB76]

So......what are your suggestions based on your actual experience with a 25" F5 Obsession? So far you appear to be referencing "some people on cloudy nights" and John in a post elsewhere on IIS

[Archy]

I, like Qld would like to know what are observers' recommendations based on their experience with large f5 scopes. As I have scant experience with a 25" f5 scope, and no experience with low power eyepieces in such a scope, I am not offering any recommendations.

[Steffen]

I suppose (and I'm speaking in complete absence of personal experience here) if one was after a really big AFOV one could give the WO UWAN 28 a shot, which Tom Trusock characterises as a close second to the Naglers. It is just as big and heavy as the 31T5 but can be had from WO directly for US$359 shipped at the moment.

Just saying… ;)

Cheers
Steffen.

[astro744]

"televue low power eyepieces agree with every one"; for good reason because they work well.



I'll second that.



"money is not a issue"; buy one of each that you feel may work well and tell us which is best.

For what it's worth my vote is for the 31mm Nagler with or without a Paracorr depending on if coma bothers you or not at f5.

[Archy]

As to ".....televue low power eyepieces agree with every one...." In Cloudy Nights, some observers do not agree.
I replicate one observer's comment From CN: "My 12.5" f/5 needed a Paracorr on every eyepiece. Coma was intolerable in the 31, 22, 17, and 16 Naglers, as well as the 35 and 22 Panoptics, and 21, 13, and 8 Ethoses." There are others.

As to "money is not a issue" I take it that Qld used the expression in the sense that cost should not be taken to account in making the recommendation.

As to "buy one of each that you feel may work well and tell us which is best" the purpose of Qld's question is to avoid doing that by eliciting other people's experience before paying out a lot of money for an eyepiece that may not be quite satisfactory in large low f ratio scopes.

A Post by qld said http://www.iceinspace.com.au/forum/../vbiis/images/buttons/viewpost.gif (http://www.iceinspace.com.au/forum/showthread.php?p=647734#post647734)
I own a 14 and 20 Explore Scientific (100 deg) and the Ethos range of eps as well. The Explore is right up there with the Ethos, however both eps produce different but interesting views eg, when looking at Tuc 47 with the Ethos you notice the cluster is slightly brighter particularly the center stars, the same object through the same scope using the Explore Scientific shows the different colours of the stars in the cluster particularly at the center (perhaps not as bright, but that might account for the colour identification) similar outcome with Omega Centauri. The scopes I have used with these eyepieces were a 8 inch Astro System dob at f6, a10 inch Skywatcher dob, at f4.716, Lightbridge at f4.5,16 inch Obsession at 4.7 and 25 Obsession at f5. The 20mm Explore Scientific ep is in my opinion the best of the lot and no paracor is needed for it in any of the aforesaid scopes (nor for the 14 explore scientific). The same cannot be said for the ethos in faster scopes. The price is not relevant: its about performance. I am not talking about comparing the performance of these eps with cheap plossls, Andrews specials or clones of older designs as some on this forum seem to do, or speculate on performance of eps they don't have or have any experience with....the Explore Scientific range is excellent and does not need to be compared with the Ethos its like trying to compare a Falcon with a Holden ....pretty much the same. Enjoy

Based on what you qld said, the price differential, and the high exchange rate, my ES 20 is the way from Opt Corp

I will compare the views from the ES 20 with those from an Andrews 30 to see whether the higher cost of the ES 20 is worth it.

As to "For what it's worth my vote is for the 31mm Nagler with or without a Paracorr depending on if coma bothers you or not at f5" is that based on experience with a 25" f5 scope?

[astro744]

Coma is a function of the primary parabloidal mirror and not the eyepiece. The only eyepiece that I know of manufactured to correct for coma was the 28mm Pretoria (50deg AFOV I believe). I'm not sure how effective this eyepiece was in different telescopes.

If there is field curvature present then coma is less noticeable and this may be the case with the eyepieces you mentioned above. Magnification too will impact on how easy coma is visible.

As was mentioned previously if money is no object then close second doesn't count. Also anything around 20mm cannot be considered low power or wide field for a 25" f5 so a 31mm Nagler is the best choice if you want 82deg AFOV and almost maximum true field. The only exception would be the 41mm Panoptic for a little more and maximum true field but at the expense of greater exit pupil. Giving 77x and 0.83deg TFOV, the 41 Pan may still be a good option in lieu of the 102x and 0.76deg TFOV of the 31mm Nagler.

At $559 for the 41 Panoptic and $699 for the 31 Nagler thery're a bargain. Consider the fact that several years ago the 31 Nagler was more than the cost of both now.

[Archy]

Are you speaking from experience, or is this an armchair viewpoint dressed up?

[sasup]

I have the 28mm and love it as much as my neglars

[mental4astro]

Add me to this one.

In my 8" f/4 dob, it's the only "low power" EP.

This combo outperforms my 17.5" f/4.5 at home (Sydney) with any EP you'd care to use. Out in the sticks, that's another matter.

I'm not saying there aren't better EPs. I know there are.

As for wide field, 68 deg. limit for me. No one has given me a satisfactory reason why it should be larger. 80deg. 100deg. 120deg. Why? You spend so much time stuffing around moving your head around to see the whole FOV. Look away from the EP and then back, and you again stuff around finding what you're after instead of 'there it is'. Doesn't seem like much, but add up the time over a session!

The "just because" and "space walk" reasons seems to me a clever ploy to extract money. You also run into additional optical aberations, coma, astigmatism, etc. Then more money, and extra bits to drop, to stick extra bits of glass to 'correct'. I've got a coma corrector (MPCC), came to me through 'inheritance'. I never use the blasted thing - I see less stars with it!

My eyes are human eyes.

Panoptics - COOOOL, ;), but I don't have one.

GSO Superviews - COOOOL too. I'm aware of their short comings, & I'm prepared to work with them. I've got 3.

[JethroB76]

Is that seriously the reason for not wanting a 80-100 degree FOV? My head and eyes move around fairly effortlessly

[Jeeps]

I have heard that the 80-100deg premium eyepieces are a lot easier to live with a dob because you don't need to nudge the scope so often, you can let the object drift for much longer.

I have the 20mm and 30mm GSO Superviews and apart from my TMB planetaries they are the only ones i use. I have found them to be much better than the eyepieces that came with my scope but i've never looked through a Televue/Pentax/ES etc. With my f/4.8 scope i get heaps of distortion on the outer 40% or so of my 30mm and about the outer 20% of my 20mm.

I plan to buy some premium eyepieces next year to compare, and if i don't like them i'll sell them ;) I find the slightly extra field of view on my superviews much easier to live with so i guess a 100 degree field of view would be very nice to use :)

cheers

[rmcconachy]

It's a taste thing and completely personal. Some people want to keep their eye still and see a crisp field stop. Some people want to be able to roam around and never see a field stop if they look near the center of the field of view. As Sam points out, a wider field of view is relatively more useful in a non-tracking scope such as a typical dob.

[mental4astro]

Is that the only paragraph you read?

rmcconachy finished it nicely. Thank you.

[JethroB76]

No, I read it all. They sound almost like "just because" reasons as well

[mental4astro]

;) , may be, but I'm happy with that too. Like I said, my eyes are human, and I have my preference. Just like you do. I'm cool with that, :thumbsup: .

[JethroB76]

:lol:

[Shano592]

I bought the 21mm Ethos and the 41mm Panoptic.

They each have their place.

The Panoptic is great for the 82deg AFOV, while having the lower magnification to take in a large area.

The Ethos is the thing for getting in a little tighter, to close-in objects.

I am only speaking from experience with the LX-200 though, not a giant dobsession...

[astro744]

The 41mm Panoptic has only 68deg AFOV. However it is an excellent choice for an f10, LX200 giving 4.1mm exit pupil.

Also the 46mm field stop diameter of the 41P is considerably larger than the 36.2mm field stop diameter of the 21E giving a noticeably larger true field. The 31mm Nagler with 82deg AFOV falls in between with a 42mm field stop diameter and 3.1mm exit pupil (f10).