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  #1  
Old 18-03-2015, 04:15 PM
kimmik (Kim)
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Nothing is better than a 25mm Plossl?

In theory, there are many eyepiece designs "better" than Plossl, which is your basic "good" eyepiece. But are there??

So far, i have not found anything that I can say "yep, i dont miss the 25mm plossl in any way whatsoever", even when price is no object. I dont mean just 25mm eyepieces, but everything considered is there one eyepiece that makes you never miss any aspect of the 25mm plossl again? As important as sharpness and AFOV are things that make viewing/using comfortable, like:

The 25mm Plossl:
22mm eye relief is excellent
No kidney beaning/blackout (i.e. minimal spherical aberration of the exit pupil) is excellent
Minimal field distortion/pincushion
Light, well balanced and tough
Pretty sharp across the field

Summed up, with a 25mm plossl on the scope, one can easily and comfortable see a nice clear image, without having to rebalancing the scope or making any thumbscrews super tight.

What I've used so far:
100deg ES20 - yes its sharp and huge fov, but ER is short and there's kidney beaning. its also big and unwieldy.
68deg 4 element and 5 element GSO - soft periphery, shorter ER, but i do quite like this eyepiece too.
60deg 6 element Celestron LX - good ER but kidney beaning, and is chunky.

The possible contenders from what I can see, are:
Nagler T6, similar size as the plossl, but better in almost everyway? not sure about kidney beaning or pincushion distortion as i haven't used one.
Orion Stratus, great 20mm relief (big 31mm eye lens), but 400g is heavy...
Panoptic 19mm? though ER is only 13mm

Does any particular eyepiece best just about everything the 25mm Plossl has, without compromise? Not just optically, dont forget ease of use and comfort of viewing.

Last edited by kimmik; 18-03-2015 at 04:39 PM.
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Old 18-03-2015, 05:14 PM
Renato1 (Renato)
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You haven't said on what telescope your 25mm eyepiece has been so good.

For me, the most important factor is exit pupil. So that my 25mm eyepieces only really get used a lot in my f/12 Maksutovs, where they are always good. Whereas on my f/10 C8 I didn't use 25mm eyepieces much, as 20mm was better for faint stuff, and 30 or 40mm was better for lower power viewing. And I've only rarely used 25mm or 26mm in my f/4.5 dob.
Regards,
Renato
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  #3  
Old 18-03-2015, 05:40 PM
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ZeroID (Brent)
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The still rather ordinary GSO SV 20mm works for me. I have both the 25mm Plossl and the 20mm SV and for field and view they are almost interchangeable IMO.
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  #4  
Old 18-03-2015, 06:03 PM
kimmik (Kim)
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The properties i mentioned, like spherical aberration of the exit pupil, and weight for example are intrinsic to the eyepiece and not dependent on the scope.

Though yes having a different scope will make it more or less pronounced - e.g. a large exit pupil will mask kidney beaning, and having a heavy scope will mask the effect of a heavy eyepiece.

If you must know, I use an f9 refractor and an f9 cassegrain.

I agree that the GSO Superviews are very good, even though they are not the sharpest around the periphery like some super corrected designs. They are however super easy to use and does not strain the eye at all!
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Old 18-03-2015, 07:07 PM
kimmik (Kim)
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Just found this thread, interesting read:

http://www.cloudynights.com/topic/48...ut-eyeglasses/


Quite a few mentions for 25mm Plossl and the 20mm GSO Superview. Also Delos, XW, T6 Nagler, Panoptic 24mm.
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Old 18-03-2015, 07:58 PM
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LewisM
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I use 2 eyepieces - a 24mm Takahashi LE and a Vixen 8-24 Zoom. I am about to get a TV 24mm Panoptic to round out the set.

I use a 100mm f/8 Takahashi FC-100 (original model,not not the recent remakes)
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Old 18-03-2015, 08:50 PM
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Allan
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I have TV Plossls I use in the bino. I really like the 20mm and the 25mm is pretty good as well. I have never met an eyepiece that is better on Jupiter than the TV Plossls. The warm tone brings out contrast in the belts beautifully. Plus fairly sharp and minimal scatter.

Occasionally I slip one into the focuser in mono mode and pan around the deep sky. This exercise tells me I far, far prefer my wide fields for observing DSO's. In the telescopes I own they perform much better for that type of observing.
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  #8  
Old 18-03-2015, 10:45 PM
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barx1963 (Malcolm)
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One piece of advice I give new observers is don't be in a hurry to trade up to new expensive EPs. Main reason is that in a dob, the 25mm plossl that often comes with the scope is going to do some very nice jobs on many of the objects that they will want to look at.
I can still remember my first views of Omega Cent in both 8" and 12" dobs which were both with a 25 plossl and it blew my mind both times.

Malcolm
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  #9  
Old 19-03-2015, 12:20 AM
Renato1 (Renato)
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Quote:
Originally Posted by kimmik View Post
The properties i mentioned, like spherical aberration of the exit pupil, and weight for example are intrinsic to the eyepiece and not dependent on the scope.
Those properties may arguably be better in a 25mm Plossl, but the notion you infer - that as such, they make it a better eyepiece in any telescope - does not follow.

In f/9 telescopes like you have, a 25mm Plossl gives a 2.8mm exit pupil, which is fine for brighter DSOs, but slightly suboptimal for the very faint ones.

In an f/4.5 dob, yes, a 25mm eyepiece will give nice eye-popping bright images of bright DSOs, but it will be extremely suboptimal for identifying and seeing anything interesting in very faint DSOs.

In my C8, for years my favourite eyepiece was a wide angle 20mm Erfle. On the negative side, it had lousy eye-relief and very poor edges compared to my 26mm Plossl. On the positive side, time and again I was easily able to spot and get good views of very faint galaxies with hardly any effort, compared to the 26mm Plossl.

Regards,
Renato
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  #10  
Old 19-03-2015, 04:35 AM
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erick (Eric)
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25mm Plossl, f5 scope, H-Beta filter, Horsehead - say no more!
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  #11  
Old 19-03-2015, 08:14 PM
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AG Hybrid (Adrian)
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My 150mm and 300mm newtonian's both came with 25mm plossls. They were bloody awful. The lack of coma correction at F5 is brutal. Eye relief is fine and the very center of the field was good. Otherwise paper weights.

What about the Panoptic 24mm or the cut price ES24mm 68. The Vixen LVW 22mm? All 3 of these are head and shoulders above plossls.
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  #12  
Old 19-03-2015, 09:12 PM
knightrider
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I've still got my 25mm Plossl. It gives great sharp clear views in my 10" DOB. No kidney beaning near the edges. I use it first up as my spotting eye piece, then also for views of galaxies. I feel no need to replace it with anything and it has no duplication in its focal length in my collection.
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  #13  
Old 20-03-2015, 10:08 AM
kimmik (Kim)
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Adrian, this may partly explain what you saw:

"Good Plossls are expensive to manufacture, because they require good optical glass and precisely matched concave and convex doublet surfaces to prevent internal reflections. All Plossl oculars are not created equal.

...internally blackened lens barrel with thread baffles is important, as are blackened lens edges and sophisticated anti-reflection multi-coatings. Inexpensive Plossls lacking these features deliver noticeably inferior views and are not a good value.

If well made, Plossls are bright, contrasty, with a flat field, and excellent sharpness."

http://www.chuckhawks.com/common_eyepiece_designs.htm
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  #14  
Old 23-03-2015, 08:56 PM
yoda776 (Matt)
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Well, I do and don't miss the 25mm plossl.

I don't miss it because I use it or should I say them in my orion bt100s and they give a great view of the night sky.

I do miss the 25mm plossl's first use when using in my first scope. It was a good memory to view the sky the first time and started my journey in astronomy.

Finally, on the other hand i do use other eyepieces now as a variety and have some favourites such as 12mm meade hd60 in my 80mm apo or the orion q70 2" in my orion Skyquest xx16g dob. However, I still use the plossl's for the initial find and then move on to the other eyepieces to go to the view I need at the time.
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