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Edmunds 28mm RKE

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#1 tayseidel

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Posted 30 January 2013 - 11:28 AM

How would a Edmunds Scientific 28mm RKE do on a 10" f5.6 dob? I've read that it does best on the slower f ratios, and I'm wondering if anyone likes it on a 10" f5.6 like mine. I'd be grateful for any feedback, as I'm considering buying it.

#2 Starman1

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Posted 30 January 2013 - 03:46 PM

Like all Kellners or modified Kellners, the Edmund 28 is not fully corrected to the edge at f/5.6. However, the aberrations will be largely astigmatism, and primarily in the last 10% toward the edge. Since the magnification will be low, the aberrations will have a small angular size and be largely ignorable.
As a low power eyepiece, you might be better served by a decent Plossl,
but the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.

#3 pftarch

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Posted 30 January 2013 - 09:57 PM

.....the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.


I love binoviewing them on my my f5 dob, but I was curious as to what other eyepieces do the "floaty" effect.

#4 orion61

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Posted 30 January 2013 - 10:19 PM


.....the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.


I love binoviewing them on my my f5 dob, but I was curious as to what other eyepieces do the "floaty" effect.

In 40+ years the RKE is the only eyepiece I have ever experienced that with. Even the Pre Edmund RKE 1.0 and 1.25
eyepieces don't do this. they are very unique among lenses.
The have grown from a cheap afterthought lens to a serious contender on the field.. Hence the 300% price jump since the 80's.
I worked and saved all summer in 1979 to buy one of the first Astroscans, I fell in love with them back then.
I caught a lot of flack for about 12 years untill people started to realize how good they are!
I'm old school so I cut my teeth on 35-40 degree FOV eyepieces, I have owned but, never really got into the mega lenses that cost 1/2 as much as my OTA??
I dont like the fact you have to "search" the lense for the view (9mm Naglers) just to have it Blank out if you slightly move.
The RKE are a true Workin' mans eyepiece set and are my main lenses. There are other great lenses out there for the same cost, but just like some like Ford, and some like Toyota..

#5 nevy

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Posted 31 January 2013 - 12:01 AM


.....the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.


I love binoviewing them on my my f5 dob, but I was curious as to what other eyepieces do the "floaty" effect.

I always thought the 26 mm Meade smoothie had a similar effect , I think it's pretty cool as it also seems like you are looking through a huge hole in the side of the telescope , I thought that the 32 mm might do the same but I haven't tried it out yet.

#6 ibase

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Posted 31 January 2013 - 01:11 AM

Favorite quip on the RKE28mm from this long CN thread about the "floaty" EP:

..the RKE (28mm) will distort at the edges, but you won't care ;)


Best,

#7 Starman1

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Posted 31 January 2013 - 01:47 AM


.....the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.


I love binoviewing them on my my f5 dob, but I was curious as to what other eyepieces do the "floaty" effect.

32mm University Optics Konig
32mm Meade Series 4000 pre-1994 5-element "Super Plossl" 32mm
35mm Parks Gold Series/Antares Elite/Baader Eudiascopic/Orion Ultrascopic
These are the ones I've owned that, in the scopes in which I used them, produced images that just sort of "hung" in front of the telescope as if the eyepiece weren't there.
I think the Edmund 28 RKE may be the only one still in production, but the others appear used from time to time.
I think it's an effect produced by a large eye lens with a thin barrel surrounding it and a long eye relief. None of them has/had a rubber eyecup, either.

#8 Mariner@sg

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Posted 31 January 2013 - 02:48 AM

32mm University Optics Konig
32mm Meade Series 4000 pre-1994 5-element "Super Plossl" 32mm
35mm Parks Gold Series/Antares Elite/Baader Eudiascopic/Orion Ultrascopic
These are the ones I've owned that, in the scopes in which I used them, produced images that just sort of "hung" in front of the telescope as if the eyepiece weren't there.
I think the Edmund 28 RKE may be the only one still in production, but the others appear used from time to time.
I think it's an effect produced by a large eye lens with a thin barrel surrounding it and a long eye relief. None of them has/had a rubber eyecup, either.


Hi Don, would that be the 32mm Konig-II or the Mk-80?

I've had the Konig-II for a while but the weather here have not been kind since, partially due to the fact that it's monsoon season in these parts (but also in part due to my many other purchases during this period).... :foreheadslap:

#9 Starman1

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Posted 31 January 2013 - 10:33 AM

It was from before there was a "Konig II". It was Labeled "Konig".

#10 Ouranos

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Posted 31 January 2013 - 10:52 AM

Would someone please explain to me what mounted and unmounted means on the Edmund Scientific website - used when describing the 28mm RKE - "unmounted".

#11 dan_h

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Posted 31 January 2013 - 11:12 AM

Would someone please explain to me what mounted and unmounted means on the Edmund Scientific website - used when describing the 28mm RKE - "unmounted".


Unmounted = glass only. In case you want to make your own eyepiece.

dan

#12 dcoyle

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Posted 31 January 2013 - 11:35 AM

To Don's description of why the 28 RKE produces its effect,

"I think it's an effect produced by a large eye lens with a thin barrel surrounding it and a long eye relief",

I would add that the angle of the volcano top taper is such that it disappears from view when your eye is in the position required by the eye relief.

Dan

#13 BillP

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Posted 31 January 2013 - 12:57 PM

I did some measures of this a ways back to try to determine the "whys" behind the effect. As it turns out, the housing rim makes up a very small amount of the view compared to the size of the eye lens. Also, at the particaly ER point for this eyepiece the rim of the eyepiece also happens to coincide with the approximate point where your eye has a blind-spot peripherally, making a portion of the rim actually vanish from your view since it is positioned at your eye's blind-spot (does for me anyway). So IMO it is this small profile that the rim has when viewed at the ER point as well as its positioning at/near the blind-spot of the human eye.

Here you go...found the thread from about a year ago...
Link - Scroll down to my post #5078703

#14 TonyTowe

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Posted 31 January 2013 - 06:43 PM

I have to agree. I've found the 26mm Meade 4000 smoothie to have a similar effect as well.

#15 Mariner@sg

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Posted 31 January 2013 - 09:39 PM

It was from before there was a "Konig II". It was Labeled "Konig".


Dang! Another one I need to hunt down.

#16 Jaimo!

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Posted 31 January 2013 - 11:15 PM


.....the Edmund RKE has the enjoyable experience of having the image seem to fill the space occupied by the eyepiece. There are a few other eyepieces that share this characteristic, but there are a lot of dedicated RKE fans who really like the 28 for this reason. As a low power eyepiece, you'll enjoy using it.


I love binoviewing them on my my f5 dob, but I was curious as to what other eyepieces do the "floaty" effect.

In 40+ years the RKE is the only eyepiece I have ever experienced that with. Even the Pre Edmund RKE 1.0 and 1.25
eyepieces don't do this. they are very unique among lenses.
The have grown from a cheap afterthought lens to a serious contender on the field.. Hence the 300% price jump since the 80's.
I worked and saved all summer in 1979 to buy one of the first Astroscans, I fell in love with them back then.
I caught a lot of flack for about 12 years untill people started to realize how good they are!
I'm old school so I cut my teeth on 35-40 degree FOV eyepieces, I have owned but, never really got into the mega lenses that cost 1/2 as much as my OTA??
I dont like the fact you have to "search" the lense for the view (9mm Naglers) just to have it Blank out if you slightly move.
The RKE are a true Workin' mans eyepiece set and are my main lenses. There are other great lenses out there for the same cost, but just like some like Ford, and some like Toyota..


I will have to disagree, I feel the Pre-RKE 1" & 1 1/8" do share the same floating effect as the current RKE, the housings are very similar. (sorry for the bad photo...)

Posted Image

Jaimo!

#17 Jaimo!

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Posted 31 January 2013 - 11:26 PM


32mm University Optics Konig
32mm Meade Series 4000 pre-1994 5-element "Super Plossl" 32mm
35mm Parks Gold Series/Antares Elite/Baader Eudiascopic/Orion Ultrascopic
These are the ones I've owned that, in the scopes in which I used them, produced images that just sort of "hung" in front of the telescope as if the eyepiece weren't there.
I think the Edmund 28 RKE may be the only one still in production, but the others appear used from time to time.
I think it's an effect produced by a large eye lens with a thin barrel surrounding it and a long eye relief. None of them has/had a rubber eyecup, either.


Hi Don, would that be the 32mm Konig-II or the Mk-80?

I've had the Konig-II for a while but the weather here have not been kind since, partially due to the fact that it's monsoon season in these parts (but also in part due to my many other purchases during this period).... :foreheadslap:


I have an illustration for Don's comment:

Left to Right: University Optics König II, Meade 4000 pre-1994 5 Element "Super Plössl", Edmund RKE

Posted Image

#18 Starman1

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Posted 01 February 2013 - 12:56 AM

Wow,
The "Collector" checks in.
It's like déjà vu all over again.

#19 Jaimo!

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Posted 01 February 2013 - 07:53 AM

Wow,
The "Collector" checks in.
It's like déjà vu all over again.


Not that good of a collector... I don't have the 35mm Parks Gold Series/Antares Elite/Baader Eudiascopic/Orion Ultrascopic, and it's a classic. Besides a picture is worth a thousand words.

Jaimo!

#20 Sarkikos

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Posted 01 February 2013 - 08:20 AM

Don,

32mm University Optics Konig
32mm Meade Series 4000 pre-1994 5-element "Super Plossl" 32mm
35mm Parks Gold Series/Antares Elite/Baader Eudiascopic/Orion Ultrascopic
These are the ones I've owned that, in the scopes in which I used them, produced images that just sort of "hung" in front of the telescope as if the eyepiece weren't there.
I think the Edmund 28 RKE may be the only one still in production, but the others appear used from time to time.
I think it's an effect produced by a large eye lens with a thin barrel surrounding it and a long eye relief. None of them has/had a rubber eyecup, either.


I have a Orion Ultrascopic 35mm and a pair of the RKE 28. I've put rubber eyecups on all of these. I really haven't noticed if the eyecups diminish the "floaty" effect.

Another "floaty" eyepiece is the Rini Modified Plossl/RKE/Reversed Kellner 45mm - whatever you want to call it. It has 36 degree AFOV, enormous eye relief at 36mm, a long Delrin(?) eyecup to place eye at right position to avoid black-outs, very sharp low power views in scopes that can use it. "Floating in space" effect similar to Edmund RKE 24mm. I sold mine a couple months ago.

Mike

#21 Sarkikos

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Posted 01 February 2013 - 08:22 AM

Alright. Who made this thread so wide? :4

Please be considerate, folks.

Mike

#22 BillP

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Posted 01 February 2013 - 09:51 AM

I will have to disagree, I feel the Pre-RKE 1" & 1 1/8" do share the same floating effect as the current RKE, the housings are very similar.


I agree with you...I have several 1-1/8" and 28 RKEs and they both behave exactly the same with the floating...they also have the same eye reliefs.

#23 Sarkikos

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Posted 01 February 2013 - 09:56 AM

If I revisit this thread, I'll be sure to click on page 2. The post which produced the Panavision effect :vomit: is on page 1. :poke:

Mike

#24 orion61

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Posted 01 February 2013 - 10:03 AM

I will have to disagree, I feel the Pre-RKE 1" & 1 1/8" do share the same floating effect as the current RKE, the housings are very similar.


I agree with you...I have several 1-1/8" and 28 RKEs and they both behave exactly the same with the floating...they also have the same eye reliefs.


OK I'm going to have to revisit that eyepiece, try it again, it has a chip in the lens so it got mothballed,
I just don't remember that effect with it, BUT it has been
25 years,and a lot of scopes ago..
Seemed to me it was a 4 element not 3, and was optically different somehow...

#25 Starman1

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Posted 01 February 2013 - 10:44 AM

I will have to disagree, I feel the Pre-RKE 1" & 1 1/8" do share the same floating effect as the current RKE, the housings are very similar.


I agree with you...I have several 1-1/8" and 28 RKEs and they both behave exactly the same with the floating...they also have the same eye reliefs.


OK I'm going to have to revisit that eyepiece, try it again, it has a chip in the lens so it got mothballed,
I just don't remember that effect with it, BUT it has been
25 years,and a lot of scopes ago..
Seemed to me it was a 4 element not 3, and was optically different somehow...

Yes, the one labeled 1-1/8" is a Plossl, not a Kellner. I had the one labeled 1" also, and it was a Kellner.






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