Eyepieces for LB12"

[astronut]

:help: please guys and gals, I've come from 30years worth of F15 scopes to my first fast F5 scope. I need advice on eyepieces that work well on an F5.
I'm prepared to pay the premium price to get good E/P's.
At the moment I have a Ultima 24mm excellent even on an F5,
second, a Sirius optics widescan 111, 16mm another excellent e/p but it only just reaches focus ( inward ) with the F5 and with a barlow forget it!!
The other e/p is the 2" 26mm that came with the LB, 2/3 of view is good, last third affected by mild coma.
I would like to have a good range from 40mm to about 7mm, taking into account I have a Meade 2X barlow- 1 1/4". Thanks, John.:)

[ving]

pentax make some great EPs john, mike just bought one from a store in victoria(seek out his recent thread) and i have been looking into siebert optics observatory class eyepieces which have a really good reputation ( www.siebertoptics.com ) :)

i am sure there will be plenty of others jumping in here with sugestions soon :)

[astronut]

Thanks, Dave I have an idea of what I'll end up with, but it's good to get opinions from others to help make the decision:rofl:

[ving]

let me guess, you are thinking televue?

you could complete the range of ultimas, they are great EPs :)

[janoskiss]

I guess you'd want wide fields...


That's good. :) Start reading reviews and looking for people with these EPs:

Pentax XW and XF
Televue Nagler, Panoptic and Radian
Vixen LVW
William Optics UWAN
... any more premo widefields?

But if you decide to be a bit more budget conscious: Orion Stratus (incl. the new 30 & 35mm!!) or Baader Hyperion. Bintel should be able to get you the Stratus.

I own a mix of EPs. Widefields: Nagler, Pano, Stratus, XF. Simple 45-50 degree: Televue plossl, Antares Elite Plossl, UO HD ortho. These all work very well in a fast Newt.

The Pentax XF is the nicest EP I own atm. Extremely impressed with the build quality and performance.

I am not a big Nagler fan, although I just bought one recently (because Al Nagler appeared to me in a dream and ordered me to buy his 17mm T4 :P :D).

[ving]

stratus in 30 and 35mm.... interesting! :D

[Miaplacidus]

Steve, I had that very same dream. The 17mm T4 is meant to be something special. What are your impressions of it? (PM me if you think we're off topic.)

Cheers,

Brian.

[janoskiss]

Blackout and kidney beaning is a major problem with this eyepiece. And they present themselves as soon as you get close enough to the lens to see the entire field. It kind of defeats the purpose of having that huge FOV. Being at a dark site with dark adapted eyes helps but does not eliminate the problem. You can definitely forget about seeing anywhere close to the full field with the Moon in view.

But I've still got to give the EP more of a chance before making up my mind about it. Despite the blackout issues, I did enjoy it very much under dark skies for one night. :D

[Starkler]

Theres a thread on CN re the 17t4 vs 16t6, and the 16 whoops it in sharpness but looses in comfort and eye relief.

[ausastronomer]

John,

I know you mentioned you want premium eyepieces, but are you prepared to go all the way price wise ? IMO the best low power widefield eyepiece for use in your 12"/F5 scope would be the 26mm Nagler T5. This costs just over $900, thats a lot of hoot for a lot of eyepiece.

With over 30 yrs experience you're obviously an old bloke like me (47), which means your pupil dillation is less than that of a younger person. Consequently I would avoid using eyepieces which create an exit pupil larger than 6mm. This causes the views to lose contrast and the sky background becomes a little "milky" and washed out. In your F5 scope this means a maximum focal length of about 30mm. Under even marginally light polluted skies this effect becomes noticeably worse.



The Widescan III is made by Kokasai Kohki in Japan. They are a high quality eyepiece but being based on a modified Erfle design are not well suited in an F5 scope, regardless of whether they reach focus or not. I would be selling it as it's a good eyepiece and someone will pay a good price for it to use in a slow SCT or MCT, then putting the proceeds towards something better suited to an F5 light cone. The 24mm Ultima is an excellent eyepiece with lovely sharp views to the EOF but it has a narrow FOV compared to the premium widefield designs. If you were to buy the 26mm Nagler T5 or the 27mm TV Panoptic as your low power widefield you may as well sell the 24mm Ultima as it would be superfluos.



That eyepiece is the Meade 26mm QX. As you have found out, it is not great in an F5 scope or at least I dont think its great. A 27mm TV Panoptic it is not !!! The 26mm Meade QX does a good job in slower scopes and again has a reasonable resale value for someone that owns a slower scope.

Additionally that aberration you are seeing, which worsens as you go further off axis, is likely to be "off axis astigmatism" and "field curvature" caused by the eyepieces' inability to cope with the steep angle of incidence of the light cone, created by the fast (F5) primary optic as it approaches the EOF. These aberrations will effectively "overpower" any coma that you would otherwise see eminating from the parabolic primary mirror. Normally with cheaper widefield eyepieces used in conjunction with fast scopes, the dominant aberration is off axis astigmatism with secondary field curvature. Using good quality properly corrected eyepieces at F5 you will normally not see much coma at the EOF and the premium eyepieces partially correct for it anyway.



Forget about 40mm eyepieces in your F5 scope, that creates an 8mm exit pupil and you and I are both wayyyyyyyyyyy too old for that, regardless of how dark the sky is. As I mentioned above, stick to a maximum focal length of about 30mm to 32mm and I would recommend 25mm to 30mm as being the best option. Although the FOV is slightly narrower using these focal lengths the views are improved due to better contrast resulting from the smaller exit pupil.

If you care to tell me the maximum amount (ballpark) you're prepared to spend, I will give you my thoughts having regard to your budget and what you may be able to raise as a "cash back" for selling some of those eyepieces not ideally suited to your new F5 scope.

CS-John B

[janoskiss]

The 17mm T4 is plenty sharp as far as I can tell. :shrug: Though I have not critically evaluated it (however that's done). One of these days I will compare it with my 17mm TV plossl...

[wavelandscott]

I am pretty keen on my 16 mm T5 Nagler in my 12.5 in Dob...it is a nice eyepiece...a little tight on eye relief for some but I find the view really "pulls me in"...If the 26 mm T5 is as good or better (as I've heard) it must be a very good eyepiece and based on my experience with the 16 mm T5 would have no hesistation about taking the plunge if I wanted something in that size. I've opted to stay at 1.25 inch eyepieces (at least for now) and so went the route of the 24 Pan and I really enjoy this eyepeice...it is my most consistently used.

On the other end, I have a 7 mm Pentax XW and it is a keeper no doubt and I would absolutely recommend it...

Enjoy the window shopping!

[Starkler]

Its funny it goes. The eyepiece seems fine until you drop another in the focuser that trounces it.

When I was observing with Dave47 one night and I looked through his 12nagt4, then we substituted a barlowed 22mm panoptic and there was a big difference in sharpness :eyepop: in favour of the panoptic.

[astronut]

John you're nearly right, I'm 50 still a baby. But yes I have to admit the old peepers aren't what they used to be.
I was thinking of the Lanthanum and/or Pentax, I'm not discounting the Televue products it's just that they're so expensive.
So nothing bigger than 30-35mm Hmmmm........
Thanks for the advice everyone, keep it coming I want you to make up my mind for me:rofl: :rofl: ;)

[janoskiss]

Allright. I like shopping with someone else's money. :lol: Here's a shopping list for ya: ;)

30mm Stratus
22mm LVW
14mm XW
10mm XW
8.5mm XF
(7mm XW)
Antares 1.6x 2" barlow + 2" long barrel extension for using it at 2x

Got any change left over? How about a binoviewer? They are awesome! :D

[Starkler]

I like Steves list, but i would substitute a 27mm panoptic for the 30mm stratus. Just a personal preference thing but i find a 6mm exit pupil too big for anything but properly dark skies.

[Dave47tuc]

John,
Many people will come up with this or that eyepiece. And there is a lot of good advice.;)
At the end of the day for your night time observing with your 12" F5 scope a 27mm Panoptic and 10 mm Pentax XW will serve you well for life.(I'm sure I said that somewhere before:P )
You may look at many other eyepieces, and some will say no look at this or that. Please do so. But I'm positive in the end the two I have mentioned will the two you will want.:)

[ausastronomer]

Well I think Steve's list is close, but no cigar :). I really think he has one too many mid range eyepieces in there. I just don't look at DSO's with so many different ranges of medium/low power. I think you need more options at the high power end, not the low power end. I have a 27mm TV Panoptic and 20mm, 14mm, 10mm and 7mm Pentax XW's and I just never use the 20mm Pentax XW. Invariably, when observing DSO's, I jump from the 27mm TV Panoptic to sometimes the 14mm Pentax XW, but most often the 10mm Pentax XW.

Here is my take on it all:

27mm TV Panoptic, 26mm TV Nagler TV or 28mm Williams Optics UWAN. (55X)
14mm Pentax XW (107X) (this eyepiece is the least important of the other 3 main ones)
10mm Pentax XW (150X)
7mm Pentax XW (214X)
6mm UO HD ortho (250X) optional and specifically for planetary and lunar work

The 4 main eyepieces will cover an awful lot of bases and you could certainly get by very happily with just the 27mm TV Pano and the 10mm and 7mm Pentax XW's. Consider the 14mm Pentax XW the 1st luxury item and the 6mm UO HD ortho the 2nd, although it is not expensive at about $120. FYI the Williams Optics UWAN are a new series of Wide Angle eyepieces from Williams Optics. Unlike the Williams Optics SWAN series, they are not cheap, they are a premium eyepiece. I have corresponded with Tom Trussock, in the USA, about these a few months ago. He recently posted his review of them on Cloudy Nights (http://www.cloudynights.com/item.php?item_id=1433). He rates them almost the equal of the Naglers at 70% of the price and a great value purchase. I have asked Daniel from Frontier Optics to get us a 28mm to evaluate. If I like it, I will buy it and sell the 27mm TV Panoptic. So there may be a used 27mm TV Panoptic available within the next 2 or 3 months.

CS-John B

[ausastronomer]

I agree 100% Dave, they will certainly be the two most used eyepieces. They are in my 10"/F5 scope and by a fair margin. The 7mm Pentax XW would be my 3rd most used eyepiece.

CS-John B

[janoskiss]

I hear ya, but just the field of view is getting a bit small there with a 1500mm focal length scope. With the 27mm you probably won't really have much use for the 22mm LVW either because it's too close (as much as I want one ;)).

But how about a 28mm UWAN then? It's got the exit pupil sorted, a whopping great big 82 degree field and it's only a little dearer than the 27mm Pano. The eyepiece gurus on CN rate it very highly with practically Nagler T5 performance even in fast scopes. Check out Tom Trusock's review: http://www.cloudynights.com/item.php?item_id=1433

[Starkler]

For long time I was content with a 27 pan, 14 and 10.5XL's and a barlow and I still reckon I covered all bases pretty well. I would certainly agree with what John has said there.

I now have a 31 nagler and it rarely gets used because of large exit pupil size and also the fact that its a huge heavy thing to be swapping back and forth from.
I beleive the UWAN is also quite big and heavy and may also come with some ergonomic issues due to its physical design.

I miss my 27mm panoptic for the reasons that its small and light enough comparitively speaking to not be an effort to swap out, and giving awesome comfortable views even in semi light poluted places.

[janoskiss]

Sorry, I'm a little out of sync with the rest of you guys. :ashamed: I should hit refresh before replying in a stale tab.


I guess I am still used to using the mid-low power 19mm Panoptic between the 13 & 30mm, because the 30mm Superview is just not that nice to look through. (But it has been retired recently in favour of a 27mm Pano ;))