Jump to content


Photo

Kasai Astroplan eyepieces?

  • Please log in to reply
13 replies to this topic

#1 Greg77

Greg77

    Vostok 1

  • -----
  • Posts: 148
  • Joined: 02 May 2009
  • Loc: Slovenia, EU

Posted 27 December 2010 - 02:09 PM

Have any of you used these eyepieces, and if so, what is your opinion? :jump:

http://www.aokswiss..../astroplan.html

http://www.kasai-tra...aiastroplan.htm

CS!

Greg77

#2 BillP

BillP

    Voyager 1

  • *****
  • Posts: 12043
  • Joined: 26 Nov 2006
  • Loc: Vienna, VA

Posted 27 December 2010 - 02:31 PM

I'm not sure by any means, but to me these look like perhaps the same design as the Tak LEs in 5mm, 7.5mm, and 10mm. Anyway, I always assumed these simply clones of the Tak LEs in the shorter focal lengths.

#3 Mike Hosea

Mike Hosea

    Fly Me to the Moon

  • *****
  • Posts: 6161
  • Joined: 24 Sep 2003
  • Loc: "Metrowest" Boston

Posted 27 December 2010 - 02:58 PM

I'm not sure by any means, but to me these look like perhaps the same design as the Tak LEs in 5mm, 7.5mm, and 10mm. Anyway, I always assumed these simply clones of the Tak LEs in the shorter focal lengths.


They can't be the same as the 7.5mm and 5mm Tak LEs because those two Taks are negative-positive designs that get longer (physically) with shorter focal length. My guess, rather, is that these were formerly the Celestron Ultimas of the same focal lengths.

#4 BillP

BillP

    Voyager 1

  • *****
  • Posts: 12043
  • Joined: 26 Nov 2006
  • Loc: Vienna, VA

Posted 27 December 2010 - 05:11 PM

Mike,

Do you have a diagram of the Tak LE design? I've looked and looked and have never been able to find one.

-Bill

#5 Mike Hosea

Mike Hosea

    Fly Me to the Moon

  • *****
  • Posts: 6161
  • Joined: 24 Sep 2003
  • Loc: "Metrowest" Boston

Posted 27 December 2010 - 06:15 PM

I took one apart 2 or 3 years ago and photographed it because the issue kept coming up. Clyde Crewey sent me his 5mm. It's a doublet Barlow lens (not a Smyth lens) coupled to a doublet-singlet design similar to a 3-element Konig or RKE. I've seen but not disassembled the 7mm Tak LE and presume it to be the same with a different Barlow element. You might be able to find the photo of the 5mm Tak LE in my forum posts on Astromart, if they haven't been destroyed by Herb recently throwing me into the blue-level commercial ATM/OEM sponsor bin. I'll have to cough up $50 for a 10-pack of "vendor" ads just to log in, so I have no idea whether my old forum posts still exist or not. I'd pay the $50 if I actually had a commercial interest of any kind, but I don't, and as it happens, I don't even have anything personal that I want to sell at the moment.

At any rate, search anywhere for photos of the 5mm and 7.5mm Ultimas (was there a 10mm Ultima?) and compare to these Kasai eyepieces.

#6 BillP

BillP

    Voyager 1

  • *****
  • Posts: 12043
  • Joined: 26 Nov 2006
  • Loc: Vienna, VA

Posted 27 December 2010 - 06:48 PM

Thanks...here's what you said about it (Dec 2005):

From telescope to eye, a negative doublet, a 10mm internal field stop, a plano-convex doublet (i.e. plano facing the field end), and a convex-plano (i.e. convex facing the field end) singlet. The eye lens surface seems to be very slightly convex, so the eye lens might be DCX, but that top surface is relatively flat. Appears to be fully multi-coated and the coatings look first rate (very black when looking straight on with a cap on the other end). The upper two elements were spaced by about, 3-4mm or so at the edge (less in the middle, obviously). Didn't measure the height of the spacer. The field stop is not very close to the positive group's field lens surface, and the upper retaining ring is beveled.

Roland mentioned that the design was basically a three element Ortho followed by a Barlow.

I emailed you your pics if you'd like to re-post them here.

#7 Mike Hosea

Mike Hosea

    Fly Me to the Moon

  • *****
  • Posts: 6161
  • Joined: 24 Sep 2003
  • Loc: "Metrowest" Boston

Posted 27 December 2010 - 07:20 PM

Thanks. 2005? Time flies. I probably had the picture on my home PC somewhere (I'm at work right now), but I'm happy to post it here (maybe again--don't remember).

Attached Files



#8 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20631
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 27 December 2010 - 11:44 PM

Those are Celestron Ultima clones. Unlike the Ultrascopics and Parks Gold Series, the Ultimas got stocky/stubby in the 7.5mm and 5mm focal lengths. I have both a 5mm 7.5mm Ultima. The 7.5mm is bleddy awful. The 5mm is excellent. Both are from the last crop (with the red-orange circle-C logo). Earlier Ultimas featured the lighter orange horizontally bisected circle symbol. I dunno of the prescription changed through time, but my impression is that I've preferred the older units to the newer, with the exception of the 5mm.

Regards,

Jim

#9 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 23416
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 28 December 2010 - 01:43 AM

Hmm.
Astroplan. Very similar to
"astroplanokular", the Zeiss-designed 5-element design also called "Super Plossl" by some, and made by Masuyama for years.
Since all those eyepieces come/came from Japan and most came from Kasai, I'm betting these are merely the same eyepieces without the familiar brand names:
Celestron Ultima
Omcon Ultima
Parks Gold Series
Baader Eudiascopic
Tuthill Super Plossls
Meade Series 4000 Super Plossls
Orion Ultrascopic
Takahashi LE
and now
Kasai Astroplan

#10 Simoes Pedro

Simoes Pedro

    Messenger

  • *****
  • Posts: 457
  • Joined: 03 Feb 2009

Posted 28 December 2010 - 09:54 AM

Got today a astroplan 10mm. I have not tried it yet.
I can state they are not the same as meade 4000 super plossl. The plossl have a much tigher eye-relief.

#11 GaN

GaN

    Explorer 1

  • -----
  • Posts: 54
  • Joined: 05 Jun 2005
  • Loc: Europe, Czech

Posted 29 December 2010 - 12:51 AM

The eye relief isn't similar between Kasai astroplan and clone Masuyama. The "Masuyama" clone f=5mm contains 7-lens (Kasai =5lens, without internal barlow).
Nice book about eyepieces is here as follows:
http://www.brayebroo...ofEYEPIECES.pdf

#12 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20631
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 01 January 2011 - 03:46 PM

The thing is, those eyepieces are not all the same, at least not in every focal length.

The 5mm Celestron Ultima, like the 5mm Masuyama, but unlike the 5mm LE, 5mm Ultrascopic, etc., is a short, stubby eyepiece.

The 5mm Ultrascopic, for example, has 7 elements. The 5mm Ultima, in contrast, has 5. The pictured 5mm looks like the stubby Ultima and unlike the taller Ultrascopic and clones.

The 5mm Ultima is pictured in front:

http://www.enerdynet...&view_records=1

The Orion is much taller, as is the Parks Gold Series version.

Regards,

Jim

#13 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 23416
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 01 January 2011 - 05:45 PM

When these eyepieces were introduced to the US, the barlow sections in the 3.8mm and 5mm Parks Gold Series/Ultrascopics could be removed.
That meant you essentially got two eyepieces in one--a 10/5 couple or a 7.5/3.8 couple.
A few years later they started cementing them together so the barlow couldn't be removed from the eyepiece.
I had a complete set, and the barlow lens could be inserted in several of the eyepieces, not just the 10 and 7.5.
Most of the companies selling these eyepieces didn't have the shorter focal lengths as separate, 5-element, eyepieces because of the extremely short eye reliefs. Adding the internal barlows made the shorter focal lengths with the eye reliefs of the longer eyepieces, which were, in their own rights, already extremely short.

#14 Simoes Pedro

Simoes Pedro

    Messenger

  • *****
  • Posts: 457
  • Joined: 03 Feb 2009

Posted 03 January 2011 - 06:10 PM

I have had now a few eyepiece time the the 10mm Astroplan.

The eye-relief is a bit tight (stated as 8.5mm), but increased to a fairly comfortable level when the eyepiece was barlowed 2x.

This eyepiece gave wonderful views of Jupiter at 160x with a TSA-102. The image of the planet was sharp, even at the edge, but the planet suffered visible "stretching". Like and ellipse.

The eyepiece was tested as well, on two tight doubles - Alnitak and Eta Orionis. Both stars were split even at the edge of the field.

Overall, I feel this eyepiece is very good value.

Currently they sell in Europe for 100€, a +30€ premium over a 9mm volcano top kasai ortho.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics