Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Eyepieces

Pages: 1 | 2 | (show all)
BillStar
Pooh-Bah


Reged: 07/29/10

Loc: Connecticut & North Carolina
32mm RKE wide angle Erfle?
      #4308376 - 01/11/11 10:39 PM

Has anyone used this eyepiece? How might it perform in an f/10 SCT?

http://www.anchoroptics.com/catalog/product.cfm?id=193

Comments?
Caveats?
Criticisms?


Post Extras: Print Post   Remind Me!   Notify Moderator  
gnowellsct
Postmaster
*****

Reged: 06/24/09

Re: 32mm RKE wide angle Erfle? new [Re: BillStar]
      #4308534 - 01/12/11 12:00 AM

It's OK if you like sea gulls. It is also the only eyepiece I ever used that totally blacked out when I put it in a barlow.

I see many better deals over on the 'mart. one of them is being offered by me.

regards
greg n


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: 32mm RKE wide angle Erfle? new [Re: BillStar]
      #4308560 - 01/12/11 12:13 AM

"RKE" stands for "Rank Kellner Eyepiece". It is pretty much a standard Kellner reversed. Dr. Rank also designed the eyepiece you linked, allegedly, but it's *not* and RKE despite Edmund slapping "RKE" on it. It's just an Erfle. Calling an eyepiece an "RKE Erfle" is like calling an eyepiece a "Plossl Abbe Orthoscopic".

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productid=2074

I've been wanting to try one of these for a long time, but $225 for an Erfle always seems a little steep. I have an excellent 2" Meade 32mm Research Grade Erfle, and it cost me about $100. If you go for it, keep us posted.

Regards,

Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
gnowellsct
Postmaster
*****

Reged: 06/24/09

Re: 32mm RKE wide angle Erfle? new [Re: jrbarnett]
      #4309059 - 01/12/11 09:39 AM

They tend to sell used on Astromart for about $100 or less. I remember I didn't get a very good price for mine. It was one of my earliest 2" eyepieces. I eventually accumulated the older style Meade SWA 32mm and a UO Konig 32mm (the good old UO) which were both mid range eyepieces in their day and both outperformed the 32 erfle. (It does however look cool)

That was quite a while ago. I converted to XWs some time after that.

Greg N


Post Extras: Print Post   Remind Me!   Notify Moderator  
psu_13
sage


Reged: 05/30/10

Re: 32mm RKE wide angle Erfle? new [Re: gnowellsct]
      #4309080 - 01/12/11 09:50 AM

I recall reading this...

http://www.astromart.com/articles/article.asp?article_id=793


Post Extras: Print Post   Remind Me!   Notify Moderator  
BillStar
Pooh-Bah


Reged: 07/29/10

Loc: Connecticut & North Carolina
Re: 32mm RKE wide angle Erfle? new [Re: psu_13]
      #4309166 - 01/12/11 10:36 AM

Quote:

I recall reading this...

http://www.astromart.com/articles/article.asp?article_id=793



Thanks,
That's a surprising report.

Bill


Post Extras: Print Post   Remind Me!   Notify Moderator  
dan_h
Carpal Tunnel


Reged: 12/10/07

Re: 32mm RKE wide angle Erfle? new [Re: BillStar]
      #4309283 - 01/12/11 11:40 AM

Quote:

Quote:

I recall reading this...

http://www.astromart.com/articles/article.asp?article_id=793



Thanks,
That's a surprising report.

Bill





How does a report entitled "31mm Televue Nagler versus 32mm Edmund Erfle", conclude with , "The sharpest eyepieces I have ever used in scopes that are f7 and over is the Brandon by Vernonscope."

Simply incredible.

dan


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: 32mm RKE wide angle Erfle? new [Re: dan_h]
      #4309350 - 01/12/11 12:10 PM

Yeah, I have noticed that conventional Erfles often do very well on-axis too, but I gotta question the merits any review that casually discards the "outer 35%" of the field in a review of wide field eyepieces. You may as well use a Plossl or Ortho if you could care less about outer 35% of a 65-degree AFOV.

Of course, the Brandon "name dropping" bit at the end, like a ward against the Evil Eye, restored a little credibility, but still...

- Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: 32mm RKE wide angle Erfle? new [Re: BillStar]
      #4309358 - 01/12/11 12:13 PM

Quote:

Quote:

I recall reading this...

http://www.astromart.com/articles/article.asp?article_id=793



Thanks,
That's a surprising report.

Bill




I suggest not trading in that 31mm Nagler.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: 32mm RKE wide angle Erfle? new [Re: Jon Isaacs]
      #4309362 - 01/12/11 12:17 PM



- Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob Myler
Pooh-Bah
*****

Reged: 05/18/06

Loc: St Louis, MO
Re: 32mm RKE wide angle Erfle? new [Re: jrbarnett]
      #4310559 - 01/12/11 09:47 PM

Quote:

"RKE" stands for "Rank Kellner Eyepiece". It is pretty much a standard Kellner reversed. Dr. Rank also designed the eyepiece you linked, allegedly, but it's *not* and RKE despite Edmund slapping "RKE" on it. It's just an Erfle. Calling an eyepiece an "RKE Erfle" is like calling an eyepiece a "Plossl Abbe Orthoscopic".

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productid=2074

I've been wanting to try one of these for a long time, but $225 for an Erfle always seems a little steep. I have an excellent 2" Meade 32mm Research Grade Erfle, and it cost me about $100. If you go for it, keep us posted.

Regards,

Jim




I have one wedded to the back end of an old Edmund inspection scope - now used as a finder. The combination weighs almost 3-1/2 pounds but the views are luxurious.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GaryJCarter
sage
*****

Reged: 06/06/09

Loc: Fairview, Texas
Re: 32mm RKE wide angle Erfle? new [Re: Bob Myler]
      #4310965 - 01/13/11 02:06 AM

Apparently he wasn't all that enamored with the Edmund...

http://www.astromart.com/classifieds/details.asp?classified_id=698284


Post Extras: Print Post   Remind Me!   Notify Moderator  
JIMZ7
Pooh-Bah
*****

Reged: 10/22/05

Loc: S.E.Michigan near DTW
Re: 32mm RKE wide angle Erfle? new [Re: GaryJCarter]
      #4311219 - 01/13/11 08:26 AM

I had a 32mm U.O. 2" Erfle once and it was the only eyepiece I used that saw the "black rift" through M-31 Galaxy in a 8" f/6.9 reflector in my light pollution location.

Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
drollere
Pooh-Bah
*****

Reged: 02/02/10

Loc: sebastopol, california
Re: 32mm RKE wide angle Erfle? new [Re: JIMZ7]
      #4311694 - 01/13/11 12:41 PM

minor point of correction: the edmund "RKE" is a kaspereit, not an erfle.

the three original erfle designs are either 1-2-2 or 2-1-2 designs (two doublets, with a singlet at either the field end or the middle). taylor's historical article on inverting eyepieces lists only the 2-1-2 form, as "origin unknown"; chris lord's paper on the evolution of eyepieces is the only source i can find that lists them all. however one or another version of the erfle turns up in ray tracing eyepiece examples, for example in the zeiss "handbook of optical systems".

if you look at the schematic, the edmund is a 2-2-2 design (three doublets). that's kaspereit's "improvement", patented a few years after the erfles.

we must all marvel at the scope of action that allows marketers to retrofit the designation "RKE" (reverse kellner eyepiece, not rank kellner eyepiece) to apply to a design that has nothing to do with either rank or kellner.

oh beware, ye users of "panoptic", "plossl", "erfle", "ortho", "kellner", "RKE", "super wide", "ultra wide", "maxi wide" eyepieces. ye may not know what ye have.

Edited by drollere (01/13/11 03:50 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: 32mm RKE wide angle Erfle? new [Re: GaryJCarter]
      #4311980 - 01/13/11 02:39 PM

I dunno. He kept it for 20 years...

"I have compared this Edmund 32mm Erfle to many eyepieces over the last 20 years. It is sharper on axis than any plossl, 1RPD, Proxima,etc. It comprises 3 achromats and is tack sharp."

http://www.astromart.com/articles/article.asp?article_id=793

- Jim

Edited by jrbarnett (01/13/11 02:40 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: 32mm RKE wide angle Erfle? *DELETED* new [Re: drollere]
      #4312007 - 01/13/11 02:48 PM

Post deleted by jrbarnett

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike Hosea
Postmaster
*****

Reged: 09/24/03

Loc: "Metrowest" Boston
Re: 32mm RKE wide angle Erfle? new [Re: jrbarnett]
      #4312133 - 01/13/11 03:33 PM

I had one of these for awhile for use in a 10" f/5 Teleport. I'm having hard time remembering too much about it. I remember liking it better than I expected to, much better than the 30mm Widescan II, which isn't saying a whole lot. As has been pointed out, the used prices on these weren't so bad, but that was really for a previous age, one without Meade QX's and other inexpensive 2" superwides. IMO, it's not an interesting option to try new, strictly a used-market eyepiece for < $100. I sold mine at $80 in 2004 (when they were still $225 new).

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike Hosea
Postmaster
*****

Reged: 09/24/03

Loc: "Metrowest" Boston
Re: 32mm RKE wide angle Erfle? new [Re: drollere]
      #4312502 - 01/13/11 06:23 PM

Quote:


we must all marvel at the scope of action that allows marketers to retrofit the designation "RKE" (reverse kellner eyepiece, not rank kellner eyepiece) to apply to a design that has nothing to do with either rank or kellner.





Yes, they trademarked it in the late 70's. When companies do that with acronyms, they sometimes do jettison the initial meaning.

It's a side issue, but I'm not too sure exactly what RKE originally stood for. There are 3 or 4 variations that get reported on. Unfortunately, the matter has passed beyond the institutional memory of Edmund (IIRC), not that they'd be likely to say, anyway, even if they knew.


Post Extras: Print Post   Remind Me!   Notify Moderator  
drollere
Pooh-Bah
*****

Reged: 02/02/10

Loc: sebastopol, california
Re: 32mm RKE wide angle Erfle? new [Re: jrbarnett]
      #4314464 - 01/14/11 03:54 PM

Quote:

"It comprises 3 achromats and is tack sharp."




somebody should let astronomers know that tacks are not really very sharp.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: 32mm RKE wide angle Erfle? new [Re: drollere]
      #4314643 - 01/14/11 05:20 PM

Quote:

Quote:

"It comprises 3 achromats and is tack sharp."




somebody should let astronomers know that tacks are not really very sharp.






That's not only the funniest thing I have read in quite some time but the most perceptive as well. "Tack Sharp" is a popular cliche used to describe equipment but as you say, tacks are not very sharp.

And razors, well, they are sharp but they do not a point, a scope or eyepiece that is razor sharp might just be astigmatic.

Needle sharp is more appropriate but maybe the best description ASFMTS... "Atomic Force Microscope Tip Sharp."

Tips of AFM's can be as small as 2 nanometers, much smaller than an airy disk.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
23 registered and 33 anonymous users are browsing this forum.

Moderator:  ausastronomer, Scott in NC, iceblaze 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1961

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics