Kellner vs Ploessl

Discuss telescope eyepieces.
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mikemarotta
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Kellner vs Ploessl

#1

Post by mikemarotta »


Is it just a matter of a fraction of a dollar in production costs?

What are the advantages and disadvantages?

https://spie.org/publications/pm92_1123 ... l_eyepiece
https://spie.org/publications/pm92_1122 ... r_eyepiece

https://www.edmundoptics.com/knowledge- ... -eyepiece/

Just for myself, I was somewhat surprised to see a Takahashi Kellner.
Takahashi Kellners.jpg
I think that speaks well for the design.
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Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: Kellner vs Ploessl

#2

Post by Lady Fraktor »


Plossl eyepieces will generally work well down to f/4 but Kellner designs typically suffer at short focal lengths (f/7 and faster) and are better with longer focal lengths. (generalization)

These eyepieces are not made by Takahashi but a company called Starbase that Takahashi carries.
From reviews the quality is supposed to be decent
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Re: Kellner vs Ploessl

#3

Post by notFritzArgelander »


Lady Fraktor wrote: Fri Jul 02, 2021 7:20 pm Plossl eyepieces will generally work well down to f/4 but Kellner designs typically suffer at short focal lengths (f/7 and faster) and are better with longer focal lengths. (generalization)

These eyepieces are not made by Takahashi but a company called Starbase that Takahashi carries.
From reviews the quality is supposed to be decent
All true. Kellners suffer in fast scopes to be sure. The main advantage of a Kellner over a Ploessl is that there is less glass on so absorption losses should be smaller. Whether that is realized in practice depends on the coatings, if any. :)

I acquired a set of these eyepieces and my first lights with them were happy experiences.

viewtopic.php?p=100099#p100099

viewtopic.php?f=6&t=13179&p=111483&hili ... FA#p111483

The expected advantage of more light throughput on DSOs was realized. On planetary the KK Orthos won.

I plan to use them as part of an ultracompact travel kit and also, because of the greater light throughput, I think they will be very nice in finder scopes with swappable eyepieces.
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Re: Kellner vs Ploessl

#4

Post by Bigzmey »


notFritzArgelander wrote: Fri Jul 02, 2021 8:08 pm
Lady Fraktor wrote: Fri Jul 02, 2021 7:20 pm Plossl eyepieces will generally work well down to f/4 but Kellner designs typically suffer at short focal lengths (f/7 and faster) and are better with longer focal lengths. (generalization)

These eyepieces are not made by Takahashi but a company called Starbase that Takahashi carries.
From reviews the quality is supposed to be decent
All true. Kellners suffer in fast scopes to be sure. The main advantage of a Kellner over a Ploessl is that there is less glass on so absorption losses should be smaller. Whether that is realized in practice depends on the coatings, if any. :)

I acquired a set of these eyepieces and my first lights with them were happy experiences.

viewtopic.php?p=100099#p100099

viewtopic.php?f=6&t=13179&p=111483&hili ... FA#p111483

The expected advantage of more light throughput on DSOs was realized. On planetary the KK Orthos won.

I plan to use them as part of an ultracompact travel kit and also, because of the greater light throughput, I think they will be very nice in finder scopes with swappable eyepieces.
Good to know nFA! Low glass count matters only if it well executed.

For me it is somewhat painful to exercise averted vision with EPs of less than 50 deg FOV. So, after a few hits and misses my low count glass set consists of BCOs and Plossls.
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Re: Kellner vs Ploessl

#5

Post by j.gardavsky »


Re: Kellner vs Plössl, or Kellner and Plössl ?

When at f=20mm,

then there may be still a good reason to have both of them when they are from Carl Zeiss Jena,
Kellner type eyepieces CZJ and Reichert.jpg
These old CZJ and Reichert (Vienna) are single coated, but still optically the highest quality Kellners on te 2nd hand markets.

And there is still a very nice f=25mm symmetrical Plössl (convex out) with the moderm multicoatings from the CZJ surplus,
gallery_316833_11917_8682.jpg
available here: https://www.ebay.de/itm/291338906023

The Kellners have at the long focus lengths just a minimum of light path through the glass (Glasweg), as not Fritz has correctly written.

The best way is to have the both, Kellners and Plössls,
JG
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Re: Kellner vs Ploessl

#6

Post by WilliamPaolini »


I personally find that Kellners are hidden gems. They have gained this reputation in the modern era as being poor performers. Nothing can be further from the truth IMO and IME with testing. Are they "perfect" to the edge in fast scopes? Of course not. But not being perfect to the edge does not make an eyepiece "poor" in my estimation as there is a lot of FOV to examine for performance and not simply the edge of field that matters and it is not simply star points that matter either. If one limits themselves to thinking that star point performance defines how good an eyepiece is then they will be missing a lot of capability that various simpler designs offer over modern complex counterparts.

At any rate, a fellow observer from Australia was kind enough to loan these Kellners to me for a look-see a while back. Not sought-after premiums by any means, but good solid build economy eyepieces. I disassembled one to confirm it is a Kellner design and it is. On ebay I see these for sale from Australia for a price of about $53 USD for all three, and shipping around $18 USD to the U.S. So that's a total of $71 for 3 eyepieces, or about $24 each. Not bad for a well built eyepiece (all metal build except for the rubber eye guard.
Pic2.jpg
Pic1.jpg

Marketing specs are interesting in that they only mulitcoated the 25mm whereas the 20 and 10 are single coated. Being just a 3-element 2-group design not sure multicoating is really necessary although always nice when the eye lens is multicoated to help mitigate eyeball glint and reflections from street lights and such. Given a 99% efficient multicoating the overall theoretical transmission efficiency of the 25mm should be around 96%, while the single coated only 20mm and 10mm should be around 93%, so in either case very good. Also interesting in the marketing is they are touting these will work well in sub f/6 instruments! Not a claim that makes sense given their generous AFOV for a Kellner, but we will see when I place them in the 80mm f/6.25 I have.

In the hand they feel quite sturdy. Holding them up to the eye they show good field stop definition in the 25mm and 20mm, and just a little less than sharp in the 10mm. Rubber eye guard is a bit thin and naturally folds down nicely and is easily removable if you desire.

I did some measures of them on the bench and got the following:

Kson K25 -- 51° AFOV; 20mm ER; 26mm Eye Lens Diameter; Fully Multicoated
Kson K20 -- 49° AFOV; 15mm ER; 23mm Eye Lens Diameter; Fully Coated
Kson K10 -- 48° AFOV; 7mm ER
Celestron K25: 45° AFOV; 13mm ER; 14mm Eye Lens Diameter; Fully Coated
20 Starbase: 50° AFOV; 9mm ER; 16mm Eye Lens Diameter; Fully Coated

Note - my older vintage Celestron Volcano has "CELESTRON KELLNER 25mm" is engraved on the bevel of the volcano. Optical Mark Circle-Dash.

As far as edge correction goes, in my TSA-102 f/8 they were all sharp out to at least 75% of the FOV, with some sharp til about 90%. Ranking of off-axis sharpness was as follows, best to worst.

1. Kson 26mm Erfle (very good out to 90%) - forgot to mention I had this one also to test.
2. Kson 25mm Kellner
3. Celestron 25mm Vintage Volcano Kellner
---
1. Kson 20mm Kellner (good out to 80-85%)
2. Starbase 20mm Kellner
---
1. Kson 10mm Kellner (good out to 85-90%)

Eye relief was really comfortable on all of them, even the 10mm Kellner! With the Kson 10mm Kellner my brow was just lightly touching the top of the eye guard and could easily see the entire FOV. With the Kson's longer ER this is a much much nicer eyepiece to use than the standard 10mm Plossls that come with scopes.

Looking at various nebula and clusters the real story came to light as star points in the off-axis took a back seat to the visual contrast of the view. The Kson 26 Erfle was clearly the shining star here and its views were just wonderful. M42 was so stark against the background and lots of mottled details in the nebula. Was really a beautiful view. The Kson 25mm and 20mm Kellners suffered from some rather large region of EOFB so the result was a very low contrast looking view in comparison. Then the Kson 10mm did not suffer from this so its views were quite pretty. Contrast of the view in both the vintage Celestron and the Starbase was very good so no complaints there. Colored stars looked to be rendered equally in all of them.

For these Kson units the 26 Erfle and 10 Kellner were really nice performers. This pair would be quite a nice set for a new scope. Remember though that this nights view was with an f/8 instrument.

So how do these work at shorter focal ratio scopes? Well I took the Kson 26 Erfle, 25-20-10mm Kellners out for a spin in my f/6.25 80mm Apo to find out. Since I last had them out I added some better blackening of the interior, specifically the section between the field stop and the field lens. This reduced the EOFB some were showing quite significantly, to the point that it was no longer distracting.

I know everyone likes to give simple 3-element designs a hard time, and when we talk Erfles you would think they were horrible, but these KSON's all performed admirably in the f/6.25 Apo quite nicely across their 50-ish degree AFOVs. Like my results in the f/8 scopes, they showed nicely pinpoint stars out to 75-80% of the FOV. Only in that last 15-20% did some astigmatism start to show. But even there it was mild not deforming the star point of any significance until that last 5-10%. So really they put up quite enjoyable views!

Of these only the 25 Kellner is fully multicoated, the Erfle just the eye lens is multicoated, and the others are only single coated. Using Sirius as the test subject I could not induce an ghosting or flare in any of them excepting the 10mm, which showed ghosts and reflections as the star was approaching the field stop and then when outside the field stop for a little. These Kson's performed so well that I even use them in my 10" f/4.7 Dob as they work extremely well. Actually a perfect beginner inexpensive and quality beginner set IMO.

These particular Kellners do not seem to be the typical, having rather large lens diameters when I compared the 25 KSON (26mm diameter eye lens) to the 25 Starbase (16mm diameter) or a vintage 25 Celestron Volcano Kellner (15mm diameter). So there is that difference, the ER feels a lot more comfortable with the KSONs, and their off-axis was tighter than other Kellners. So the optical prescription they are using for these 3-element Kellners appears to offer some better overall performance then other Kellner varieties. Btw I did take them apart and they are indeed 3-element Kellner-like designs.

They do not sell them here in the US. In Australia they go for $70 AD for the 3 Kellners, which is US dollars would be $20 an eyepiece. Given their oversized lenses, comfortable ER, nicer than cheap Plossl construction, and really nice performance even at f/6, they are quite a bargain IMO and would make a great newbie set with a first scope.

So bottom line for me is that the old Kellner design is quite nice. I also find them a preferred design for bringing out details on planetary (even when Barlowed compred to modern planetaries) and for best rendition of star colors (especially with colorful doubles). So now I have a cadre of Kellners in my eyepiece stall as they have performance surprises to leverage over the typical modern wide field. I also maintain a set of the Edmund RKEs as they perform similarly (note that they are not a Kellner or a reverse Kellner as the popular mis-wisdom likes to profess). And as for the standard Kellner, seems that there are more variations on the design than I have experienced with Plossls. Most all Plossls seem to perform more of less the same with the only difference being from those that use the TV design which has concave field and eye lenses which provide a bit tighter off-axis at the cost of a bit tighter eye relief over the standard symmetrical design. However, the various Kellners that have been marketed seem to vary more in their performance so the design is evidently tweaked from manufacturer to manufacturer more often than not based on my experiences.
-Bill

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Re: Kellner vs Ploessl

#7

Post by notFritzArgelander »


Good info. The Kellner is underrated and should be more common. The price/performance is quite favorable!
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Kellner vs Ploessl

#8

Post by Don Pensack »


Kellners and Plössls have exactly the same number of air-to-glass surfaces, so light transmission, given equal coatings, will be the same.
Glass only absorbs about 1% for 25mm of thickness in the glass, and the difference in lens thickness is too small to measure a light transmission difference.
If you ray trace the Kellner design, it isn't free of chromatic aberration even on axis.
I started out with Kellners and Ramsden eyepieces when I was young and replaced them with Plössls and the Plössls were a big step up.
And I was using an f/15 refractor at the time.
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Re: Kellner vs Ploessl

#9

Post by Richard »


I quite like a good Kellners and Plossls eyepieces , unfortunately there are many bad ones around ,as the cheap scopes include them , but a good one is sometimes what I choose in a smaller scope over the modern hand grenades
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Re: Kellner vs Ploessl

#10

Post by j.gardavsky »


notFritzArgelander wrote: Sat Jul 03, 2021 5:55 am Good info. The Kellner is underrated and should be more common. The price/performance is quite favorable!
Hello not Fritz,

this is actually the modified version of the original orthoscopic Kellner, (Albert König, and Horst Köhler, last reviewed in 1959).
The eye lens doublet aperture and thickness have been expanded, if compared with the original Kellner, and the lenses became aplanatic, similarly to the Reichert vesrion of the Kellner.
According to my POW, the Reichert aplanatic Kellner may be viewed as an intermediate modification, before the final design by König.

This modified Kellner has been described by König and Köhler in" Fernrohre und Entfernungsmesser" (3rd edition, 1959), https://www.hugendubel.de/de/buch_karto ... gQQAvD_BwE

Another nice example of the missing links in the "Tree",
JG

PS: During his 52 years with Carl Zeiss, Albert König has been working on 52 patents, and 31 commertial protective rights.
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Re: Kellner vs Ploessl

#11

Post by notFritzArgelander »


j.gardavsky wrote: Sat Jul 03, 2021 3:26 pm
notFritzArgelander wrote: Sat Jul 03, 2021 5:55 am Good info. The Kellner is underrated and should be more common. The price/performance is quite favorable!
Hello not Fritz,

this is actually the modified version of the original orthoscopic Kellner, (Albert König, and Horst Köhler, last reviewed in 1959).
The eye lens doublet aperture and thickness have been expanded, if compared with the original Kellner, and the lenses became aplanatic, similarly to the Reichert vesrion of the Kellner.
According to my POW, the Reichert aplanatic Kellner may be viewed as an intermediate modification, before the final design by König.

This modified Kellner has been described by König and Köhler in" Fernrohre und Entfernungsmesser" (3rd edition, 1959), https://www.hugendubel.de/de/buch_karto ... gQQAvD_BwE

Another nice example of the missing links in the "Tree",
JG

PS: During his 52 years with Carl Zeiss, Albert König has been working on 52 patents, and 31 commertial protective rights.
Albert König is also underrated as an heroic figure of optics. I never met a design of his I didn’t like. Thanks for the information.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Kellner vs Ploessl

#12

Post by WilliamPaolini »


Don Pensack wrote: Sat Jul 03, 2021 1:52 pm Kellners and Plössls have exactly the same number of air-to-glass surfaces, so light transmission, given equal coatings, will be the same.
Glass only absorbs about 1% for 25mm of thickness in the glass, and the difference in lens thickness is too small to measure a light transmission difference.
If you ray trace the Kellner design, it isn't free of chromatic aberration even on axis.
I started out with Kellners and Ramsden eyepieces when I was young and replaced them with Plössls and the Plössls were a big step up.
And I was using an f/15 refractor at the time.

I personally do not see the modern Symmetrical (aka Plossl) as a bug step up from modern Kellners. Both can have the same AFOV typically (like with the Kson Kellner), both transmit well, both do fairly well in the off-axis (at least down to f/6 or f/7). No doubt what you say regarding the ray trace, but the problem is that while marketing says "Kellner" one really never knows what glass types are being used. Certainly the element sizes can vary quite a but between same focal length modern Kellners (as I have seen in recent tests). Given some of my recent tests of modern Kellners the off-axis performance varies so much that to me indicates the lens prescriptions being used for these "Kellners" are probably different. From my current perspective, since I still very much use the classic designs in my observing, I much prefer the views from a modern well executed Kellner over a modern well executed Plossl.
-Bill

U.S.A.F. Veteran - Visual Amateur Astronomer since 1966 - Fully Retired since 2019
8" f/5 Newt - Lunt 152 f/7.9 - TSA 102 f/8 - Vixen 81S f/7.7 - P.S.T. - Pentax 65ED II - Nikon 12x50 AE
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Re: Kellner vs Ploessl

#13

Post by helicon »


I still have an old Edmund Scientific RKE 28mm (modified Kellner) which performs decently well in my 6" refractor. In the 10" and the 6" one of my most used eyepieces in a 2" barrel is the 30mm Erfle (standard GSO) that came with my Dob. It is my second-most used eyepiece after my Explore Scientific 18mm. I agree that Kellner's have a bad rap, which is probably undeserved.
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
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Re: Kellner vs Ploessl

#14

Post by Thomas_M44 »


I have experienced fantastic results using current production 3-element Edmund RKE eyepieces of 28mm and 21mm FL in conjunction with a 5X Powermate.

The combination of the 21mm RKE and 5X Powermate in particular, gave me the most detailed and pleasing view overall of Mars during the last opposition. Results were similar with viewing Saturn.

I also have KK orthos and TV Plossls, and so my RKE results with planetary viewing has been surprising.

I recently also obtained the quite attractive and inexpensive Japan-made Starbase Kellners of 25mm and 20mm, and hope to try them soon with the 5X Powermate and 3X TV Barlow
STARGAZING SINCE 1986

TELESCOPES: GSO 150mm f/6 Newtonian with 2” linear bearing focuser; TeleVue TV85 85mm f/7 apo refractor MOUNTINGS: Berlebach Uni Tripod with Stellarvue M2C alt/az mount head/pillar EYEPIECE SETS: Masuyama 85-Deg AFOV; TeleVue Plossl’s; KK Fujiyama Abbe Ortho's; Edmund RKE’s; Starbase Kellner's (by Takahashi) BARLOWS: Nikon EiC16 1.6X; TeleVue 2X & 3X; GSO ED 2” TELECENTRIC AMPLIFIERS: TeleVue Powermates 2.5X, 4X, 5X FILTERS, 2”: Baader Contrast Booster; Baader 570nm Orange Longpass; TeleVue Bandmate Type II Nebustar DIAGONALS: APM 2” Standard Prism (BK7); APM 2” Amici Prism (BK7) BINOCULARS: Fujinon 7X50 FMT-SX Polaris
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Re: Kellner vs Ploessl

#15

Post by SpyderwerX »


As soon as the "in-stock" becomes widely available, I'm definitely going to check out the Starbase orthos, and probably Kellners also, considering the price. I'm very curious.
~Frankie~ My mind: Always on...Slightly off. :?
Celestron CPC1100 SCT....Celestron Evolution 8 SCT...TeleVue-85 apo...SkyWatcher ST150 achro..ST102 achro..ST80 achro.
Celestron AVX...Orion Atlas EQ-G...SkyTee-2...Twilight-1.
Baader BBHS prism and mirror diagonals + Vernonscope quartz 1.25"
EPs: TeleVue oldie (NJ) & modern Plossls, Widefields, and Naglers + 3-6 zoom & Brandons 6-32.
Astronomik, Lumicon & Baader filters..
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Don Pensack United States of America
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Re: Kellner vs Ploessl

#16

Post by Don Pensack »


SpyderwerX wrote: Tue Jul 13, 2021 11:02 pm As soon as the "in-stock" becomes widely available, I'm definitely going to check out the Starbase orthos, and probably Kellners also, considering the price. I'm very curious.
Just remember, the Starbase orthos are a 2:2 design, so likely just narrow field Plössls (which could easily be orthoscopic if configured properly).
I'd be interested to see the internal configuration of the "Kellners".
Astronomer since 1963
Currently using a 12.5" dob and a 4" apo refractor
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Re: Kellner vs Ploessl

#17

Post by notFritzArgelander »


Don Pensack wrote: Wed Jul 14, 2021 6:11 pm
SpyderwerX wrote: Tue Jul 13, 2021 11:02 pm As soon as the "in-stock" becomes widely available, I'm definitely going to check out the Starbase orthos, and probably Kellners also, considering the price. I'm very curious.
Just remember, the Starbase orthos are a 2:2 design, so likely just narrow field Plössls (which could easily be orthoscopic if configured properly).
I'd be interested to see the internal configuration of the "Kellners".
IIRC there’s a thread here with a link to a site with a diagram of the “innards” which are quite Kellneresque.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Kellner vs Ploessl

#18

Post by SpyderwerX »


Don Pensack wrote: Wed Jul 14, 2021 6:11 pm
SpyderwerX wrote: Tue Jul 13, 2021 11:02 pm As soon as the "in-stock" becomes widely available, I'm definitely going to check out the Starbase orthos, and probably Kellners also, considering the price. I'm very curious.
Just remember, the Starbase orthos are a 2:2 design, so likely just narrow field Plössls (which could easily be orthoscopic if configured properly).
I'd be interested to see the internal configuration of the "Kellners".
Indeed. That's my suspicion also. Plus, for the price range, I don't hold a great deal of belief that they are a true, or quality Ortho in the end.

I do have a old set of circle (T) Kellners from back in the day, and in the proper circumstances can deliver quite satisfying results. :)
~Frankie~ My mind: Always on...Slightly off. :?
Celestron CPC1100 SCT....Celestron Evolution 8 SCT...TeleVue-85 apo...SkyWatcher ST150 achro..ST102 achro..ST80 achro.
Celestron AVX...Orion Atlas EQ-G...SkyTee-2...Twilight-1.
Baader BBHS prism and mirror diagonals + Vernonscope quartz 1.25"
EPs: TeleVue oldie (NJ) & modern Plossls, Widefields, and Naglers + 3-6 zoom & Brandons 6-32.
Astronomik, Lumicon & Baader filters..
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Re: Kellner vs Ploessl

#19

Post by j.gardavsky »


Thomas_M44 wrote: Tue Jul 13, 2021 6:41 pm I have experienced fantastic results using current production 3-element Edmund RKE eyepieces of 28mm and 21mm FL in conjunction with a 5X Powermate.

The combination of the 21mm RKE and 5X Powermate in particular, gave me the most detailed and pleasing view overall of Mars during the last opposition. Results were similar with viewing Saturn.

I also have KK orthos and TV Plossls, and so my RKE results with planetary viewing has been surprising.

I recently also obtained the quite attractive and inexpensive Japan-made Starbase Kellners of 25mm and 20mm, and hope to try them soon with the 5X Powermate and 3X TV Barlow
Thomas,

I believe you, as it is not surprizing.
The concept of the Vixen HR is very similar to an RKE with a Barlow in the nosepiece,
https://www.apm-telescopes.de/en/optica ... 2.4mm-1.25

Best,
JG
6" F/5 Sky-Watcher achro, 2" BBHS Star Diagonal, 2" zenith prism, 1.25" Takahashi prism
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
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Re: Kellner vs Ploessl

#20

Post by Thomas_M44 »


j.gardavsky wrote: Fri Jul 16, 2021 8:19 pm
Thomas_M44 wrote: Tue Jul 13, 2021 6:41 pm I have experienced fantastic results using current production 3-element Edmund RKE eyepieces of 28mm and 21mm FL in conjunction with a 5X Powermate.

The combination of the 21mm RKE and 5X Powermate in particular, gave me the most detailed and pleasing view overall of Mars during the last opposition. Results were similar with viewing Saturn.

I also have KK orthos and TV Plossls, and so my RKE results with planetary viewing has been surprising.

I recently also obtained the quite attractive and inexpensive Japan-made Starbase Kellners of 25mm and 20mm, and hope to try them soon with the 5X Powermate and 3X TV Barlow
Thomas,

I believe you, as it is not surprizing.
The concept of the Vixen HR is very similar to an RKE with a Barlow in the nosepiece,
https://www.apm-telescopes.de/en/optica ... 2.4mm-1.25

Best,
JG
JG, that is quite interesting about the construction of the Vixen HR series. I did not know this.

Thanks for the information
STARGAZING SINCE 1986

TELESCOPES: GSO 150mm f/6 Newtonian with 2” linear bearing focuser; TeleVue TV85 85mm f/7 apo refractor MOUNTINGS: Berlebach Uni Tripod with Stellarvue M2C alt/az mount head/pillar EYEPIECE SETS: Masuyama 85-Deg AFOV; TeleVue Plossl’s; KK Fujiyama Abbe Ortho's; Edmund RKE’s; Starbase Kellner's (by Takahashi) BARLOWS: Nikon EiC16 1.6X; TeleVue 2X & 3X; GSO ED 2” TELECENTRIC AMPLIFIERS: TeleVue Powermates 2.5X, 4X, 5X FILTERS, 2”: Baader Contrast Booster; Baader 570nm Orange Longpass; TeleVue Bandmate Type II Nebustar DIAGONALS: APM 2” Standard Prism (BK7); APM 2” Amici Prism (BK7) BINOCULARS: Fujinon 7X50 FMT-SX Polaris
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