Edmund RKE a classic or outdated?

Discuss telescope eyepieces.
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helicon United States of America
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Edmund RKE a classic or outdated?

#1

Post by helicon »


I still have my circa 1979 Edmund Scientific RKE, a modified Kellner design which Edmund patented back in the 1970's. It came with my red tube 4.25" reflector known as the Super Space Conqueror. Since the scope was f/10 it was pretty forgiving on eyepieces and even Kellners worked fine. Anyone still have an original RKE?



I still use mine in my 6" achromat. I think there was a hiatus as Edmund's business waned but it was reborn as Edmund Optics and they are still selling the design. Just curious what others think of them? Not as well-known as the Astroscan was in the 1970's but still an important piece of eyepiece lore.
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
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Re: Edmund RKE a classic or outdated?

#2

Post by notFritzArgelander »


I don't have one. This is only because, having what I have, it's easy to ignore temptation to buy the set. I'd vote for classic. I've had a quick look through them on other's kit. When I'm in a good mood, the floating field effect gets me giggly. When I'm grumpy, it's too gimmicky. :)
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Re: Edmund RKE a classic or outdated?

#3

Post by Lady Fraktor »


I do like the RKE eyepieces, so classics for me and still use them.
Besides the 28mm with its party trick the line is actually quite good and the prices still reasonable.
Ordering them in EU can get expensive with duty and taxes though. (€ 102+20% DPH here)
The 15mm and 21,5mm are standouts but I do not think they are produced anymore.
For refractors the RKE barlow is much to long but is good for large (300mm+) newtonians
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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Re: Edmund RKE a classic or outdated?

#4

Post by helicon »


I still have the cheap 3x barlow that came with the Edmund scope, but it's relegated to the junk drawer. I don't list it in my signature. Hard for me to throw anything astronomical away.
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Edmund RKE a classic or outdated?

#5

Post by Lady Fraktor »


I have a hard time getting rid of astro things as well until it becomes a issue :lol:
If I listed everything I would not have room to comment!

Is it a different barlow from the RKE 2.5x?
It is not my best barlow but it does work reasonably well.
These long barlows were designed for use with newtonian telescopes to have the light cone entering closer to the secondary.
It works well in my f/10 - f/15 refractors but I would not use it in anything shorter.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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Re: Edmund RKE a classic or outdated?

#6

Post by helicon »


I meant the 2.5x in general I am not a barlow fan but it worked pretty well with the 4.25" I remember zeroing in on the Trapezium through it, Hey there are four stars!
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Edmund RKE a classic or outdated?

#7

Post by Lady Fraktor »


Since you have the 28mm, you should look for a 15mm.
They are usually not very expensive used and was one of the best from the lineup.

Barlows for me are view dependant. When I do use them I actually like using odd incremental barlows.
1.6x, 1.8x, 2.4x etcetera. I have had a 2x TeleVue powermate for better than a decade now and I think I have used it maybe 3-4 times...
It does make a good but expensive paperweight though :)
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Edmund RKE a classic or outdated?

#8

Post by helicon »


I should get a 15mm as well!
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Edmund RKE a classic or outdated?

#9

Post by Lady Fraktor »


Hopefully sometime this month I may be able to recommend a 20mm as well :)

I really need to pay attention when tired, the incoming 20mm is a Brandon not a RKE.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Edmund RKE a classic or outdated?

#10

Post by WilliamPaolini »


I cannibalized from other EPs so could have a nice weighty chromed brass barrel on my set. They perform great in my scopes and show star colors exceptionally well - always want to keep a single coat set around. No one has a same barrel type as used for the 28.7mm so I just buffed the anodized layer off. RKE = Rank, Kaspereit, Erfle per the Edmund patent submission FYI. The pre-RKE 28.7mm, usually marked as a 1-1/8", is an asymmetrical Plossl war surplus optic.
RKEs Only (web).jpg
-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
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Re: Edmund RKE a classic or outdated?

#11

Post by Lady Fraktor »


I love my RKE and have used then for quite a few years.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Edmund RKE a classic or outdated?

#12

Post by WilliamPaolini »


Lady Fraktor wrote: Tue Jan 10, 2023 5:27 am I love my RKE and have used then for quite a few years.
I have bought and sold more than 300 different eyepieces over the years so have been through a lot. I had a full set of the RKEs that I added the chromed brass barrels to and after a few years sold them. Of all the eyepieces I have been through and let go of, that set was the only one I truly regretted selling. So some years later I reacquired the RKEs once more, and was lucky to be able to source a 15mm used as that focal length was already discontinued by Edmund. I have to say that will NEVER let go of my current set! I feel the same way about the Takahashi LEs. Both lines just have what I consider a unique gestalt about them that makes them special and enjoyable.
-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
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Re: Edmund RKE a classic or outdated?

#13

Post by Lady Fraktor »


I have done a mass purge of eyepieces over the last year but the RKE remain. I only have a few Tak LE but enjoy the ones I do have.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Edmund RKE a classic or outdated?

#14

Post by helicon »


WilliamPaolini wrote: Tue Jan 10, 2023 6:20 pm
Lady Fraktor wrote: Tue Jan 10, 2023 5:27 am I love my RKE and have used then for quite a few years.
I have bought and sold more than 300 different eyepieces over the years so have been through a lot. I had a full set of the RKEs that I added the chromed brass barrels to and after a few years sold them. Of all the eyepieces I have been through and let go of, that set was the only one I truly regretted selling. So some years later I reacquired the RKEs once more, and was lucky to be able to source a 15mm used as that focal length was already discontinued by Edmund. I have to say that will NEVER let go of my current set! I feel the same way about the Takahashi LEs. Both lines just have what I consider a unique gestalt about them that makes them special and enjoyable.
Good to hear. The 28mm always has been a nice performer.
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Edmund RKE a classic or outdated?

#15

Post by John Baars »


helicon wrote: Mon Jan 16, 2023 11:28 pm The 28mm always has been a nice performer.
So it is. I have mine some twelve years. Especially for the nice floating field effect. I use it mainly in my f/13 Mak. I used to have a 15mm too, but eventually sold it again as my 14mm Baader Morpheus outclassed it by far.
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
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Re: Edmund RKE a classic or outdated?

#16

Post by helicon »


John Baars wrote: Thu Jan 26, 2023 9:13 am
helicon wrote: Mon Jan 16, 2023 11:28 pm The 28mm always has been a nice performer.
So it is. I have mine some twelve years. Especially for the nice floating field effect. I use it mainly in my f/13 Mak. I used to have a 15mm too, but eventually sold it again as my 14mm Baader Morpheus outclassed it by far.
They seem to have quite a lifespan!
-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
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Edmund RKE a classic or outdated?

#17

Post by Lady Fraktor »


helicon wrote: Thu Jan 26, 2023 3:14 pm They seem to have quite a lifespan!
I think I have had my set for about 12-15 years as well.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Edmund RKE a classic or outdated?

#18

Post by WilliamPaolini »


On of the 28mm's I have, is the 1-1/8" version which is really an asymmetrical Plossl. I got that from the Edmund store with one of my first telescope's from there, a 4.25" Reflector way back in mid 60's! The showroom they used to have in Barrington, NJ was a wonderland of science stuff for adults and kids. Used to love going there. They also had a surplus room with all kinds of neat odds and ends which of course little kids just love dipping their hands into the bins and exploring those treasures. And they made the shop fun too. In the middle of the main store was an actual submarine periscope they mounted that popped out the roof of the building so you could look around. And the hallway between the main showroom and the surplus room had a bunch of those circus mirrors that distorted the view making you appear long and stretched or short and round. Just a wonderful wonderful place. Went there many times as a kid and later brought my kids there as well. So bummed when they closed it. It really was the place that got me interested in science. Online shopping cannot compare to a brick-and-mortar store where a kid can see up close and touch and feel all the unusual treasures!

Here's links to some old pics of the place...

https://www.cloudynights.com/uploads/mo ... 494975.jpg

https://cloudfront-us-east-1.images.arc ... D4P3K4.jpg

https://upload.wikimedia.org/wikipedia/ ... 0926034559
-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
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Re: Edmund RKE a classic or outdated?

#19

Post by WilliamPaolini »


As far as the outdated question, here are my thoughts...

I personally do not consider them outdated as they perform perfectly fine. Of course their 45 degree AFOV makes them a bit of an oddity in today's market. I feel they are a bit over priced given their light aluminum barrels. If they had conventional chromed brass barrels like many of the classic designs can come with then their current $107 USD price might be easier to swallow - I think $75 might be better. However, they are also one of the few single coated eyepieces available, Brandons being another and some cheap things on ebay. I like having some single coats in the stall as they provide a bit of a different view from multicoats having exceptionally dark backgrounds and IMO showing subtle star colors better and producing cleaner star points many times which is why I like them for doubles. When I had my 10" f/4.7 Dob I used to use them often in that instrument as they bought in double stars very cleanly so were preferred for that task. Yes they are only a 3 element design so the off-axis will suffer but in my testing no worse than an Abbe in faster focal ratio scopes for the 21mm thru 8mm. The 8mm is easily on par for planetary with the TV 8mm Plossl as I did an exhausting personal compare of those two over two full years and could not determine a winner, so a dead heat. Their diminutive size makes them a pleasure to take into the field so no large suitcase needed to get the set out there. The oddity of the line is the 28mm as its eye relief is very long so difficult to keep the view. The length of its eye relief and width of its housing is such that when viewing the housing is right at the blind spot in the human eye so that in addition to its very slim housing makes the housing appear to vanish so only the AFOV is there seemingly almost floating in front of you. This eyepiece also does not handle faster focal ratios well so it's off-axis can be pretty distorted with faster focal ratios. In my f/8 Apos thought it is plenty good enough, although of the line I consider the 28mm more as a novelty eyepiece for its floaty view ranter than one I would grab for general viewing. However, I found the 28mm does have a special usage that I like, and that is to Barlow to extend the eye relief even more which allows me to sketch more easily as I can stand far off from the eyepiece so I can simply move my eyes from the direction of the eyepiece to the sketch pad without dipping near the eyepiece so makes sketching much easier as like liking at something with the naked eye. So I keep a pair of those for the binoviewer as well.
-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
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Re: Edmund RKE a classic or outdated?

#20

Post by Don Pensack »


The feeling of the frame disappearing to a thin line around the image also occurs with the 9mm Morpheus, 35mm Ultrascopic, and 3-6mm Nagler Zoom as I have noticed.
The thin black "line around the field" is a bit broader than in the 28.7mm RKE (how Edmund used to label it), but each exemplifies how, when the eye relief is just the right length,
the outer barrel thins down to just a thin black line by perspective.
You do have to be able to float above the eyepiece in just the right spot, and it is easier to see without glasses.
Astronomer since 1963
Currently using a 12.5" dob and a 4" apo refractor
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