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ZEISS AS 150/2250 f/15

Auction No.:
Current Bid:
High Bidder:
federico caro
Bid History:
26 Bids [View History]
Rome, - Italy
05/15/2012 09:53AM
05/29/2012 09:53AM
ZEISS AS 150/2250 f/15
(lens in cell in original oak case)

This is something you do not see up for sale very often: a Zeiss AS150/2250 lens in cell coming from a Professional Observatory in Germany.

Designed by Dr. August Sonnefeld in 1926 (and remained in regular production till 1995...!), the Zeiss AS ("Astro-Spezial") is an air-spaced doublet made of a Kurz-Flint and a Crown glass (KzFN2/BK7) in Steinheil configuration (leading flint) bearing by design an obvious improved correction of the chromatic aberration vs. a regular Fraunhofer achromatic doublet.

It is usually reported that the AS secondary spectrum is 1/2400 vs 1/1850 for a standard BK7/F2 FH. More in detail, as per Zeiss specs, the correction is actually superior (see data from "Zeiss Astronomische Optik" regarding "Chromatic Deviations in 1/100,000ths of the Focal Length"), spanning from about 35% to almost 80% less, according to the wavelength. This means that, as per correction of chromatic aberration in selected wavelengths (e.g. those more useful for planetary observation) a Zeiss f/15 AS lens performs somewhere in between a f/20 and a f/27 comparable Fraunhofer doublet.

Add to this the proverbial exquisite correction and high super-polishing of the Zeiss production and you start picturing the actual performances of such a lens.

AND -- this is possibly the best part -- the lens being hereby auctioned is one of those specifically produced for National Observatories, not for the regular market. As such, the interferogram of this specimen shows data which rarely (if ever) can be found in regular production lenses of this size:

PV = 0.133 (lambda/7.5 @ 532 nm)
RMS = 0.015 (lambda/68.1 @ 532 nm)
STREHL = 0.992 @ 532 nm

Copy of the ownership documents from the previous Observatory are available to the buyer, as well as the original interferogram and all the contact details of those who used and tested the lens before.

I don't think I can add much more to this information, apart from saying that the reason for selling is that we have currently in use another specimen of Zeiss observatory-selected AS150. We had plans for this lens also, but the dome that had to host this telescope has been canceled due to budgetary streamlining; the same that suggested to put up the present auction. So, we won't be having a twin AS150 in the end, while one of you can have his personal one.

As a conclusion, hereunder you may find what a Master Optician like Roland Christen (Astro-Physics) had to say on a Refractors' forum about his own Zeiss AS200, the big brother of the AS150 being auctioned here:

<< I really like long refractors. (...) AS objective lenses (...) were F15 Steinheil doublets using a mild combination of abnormal dispersion glasses which produced quite good color correction for planetary viewing. I bought some of those lenses (...). I remember at one star party we set up one of these 8" scopes on Saturn and everyone who saw the planet was thoroughly impressed by the contrast and resolution. I think we were up at 750x with a 4mm Ortho, and the planet was sharp, bright and quite free of color fringing. They sold for $5k back then, and I would say that today they would bring 3 to 4 times that, if you could pry them away from their owners.>>

Now, if you scale down the magnification (from 750x to 565x -- a magnification regularly used on nights of good seeing), what has been reported matches perfectly the performances of this AS150. Not to mention that, albeit slightly giving up in diameter, the AS150 has a parallel 26% improvement of the R-C (Residual-Chromatism) Index vs. the bigger AS200.

This Observatory-selected Zeiss AS150 will be the core of a dream planetary refractor that will truly provide you with a lifetime of observing pleasure and, also by virtue of its increasing historical value, may very well become a heirloom in your own family. This is a truly rare opportunity to take on the relay and become somehow a part of Zeiss history.

If needed, the lens in its original oak case can be shipped world-wide *triple-boxed* via a Professional Courier. Don't worry: we'll fix that together.
Any further question, I am here.
Happy Bidding to you all...!

Time Placed User Bid Amount
05/19/2012 08:09AM federico caro $7000.00
05/18/2012 07:12PM Joseph Miele $3050.00
05/17/2012 12:04PM Vivek Hira $3000.00
05/17/2012 09:57AM Anthony Orzechowski $2827.00
05/17/2012 09:29AM John Biggs $2550.00
05/16/2012 07:28PM Vivek Hira $2425.00
05/16/2012 07:28PM John Biggs $2400.00
05/16/2012 07:13PM Vivek Hira $2175.00
05/16/2012 07:13PM AKIHIRO YAMAZAKI $2150.00
05/16/2012 07:52AM Vivek Hira $1525.89
05/16/2012 07:27AM Dan Schechter $1245.00
05/16/2012 07:27AM AKIHIRO YAMAZAKI $1220.00
05/15/2012 10:59PM Dan Schechter $1125.00
05/15/2012 05:42PM Mark Liu $1075.00
05/15/2012 03:28PM BRIAN GRIDER $1025.00
05/15/2012 03:28PM Scott Mortimer $960.00
05/15/2012 03:28PM BRIAN GRIDER $950.00
05/15/2012 03:27PM Scott Mortimer $760.00
05/15/2012 03:27PM BRIAN GRIDER $750.00
05/15/2012 01:24PM Scott Mortimer $355.00
05/15/2012 01:24PM Gene Cross $350.00
05/15/2012 01:20PM Scott Mortimer $305.00
05/15/2012 01:20PM Gene Cross $300.00
05/15/2012 01:20PM Scott Mortimer $202.50
05/15/2012 01:20PM Gene Cross $200.00
05/15/2012 11:04AM Scott Mortimer $1.00

Massimiliano Lattanzi (massimilianolattanzi)



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