The mysterious Goerz '3D' Condenser! [Updated 30 Mar 17]

A little-known child of the "Flower Power" era, this unique device was served-up with a thick layer of marketing hype, such as "plastic field," and similar nonsense. 

Sold by the C. P. Goerz American Optical Company, the device had nothing to do with the "real" American Optical Co., and the cryptic labeling was a cause for much confusion (and perhaps even some litigation). 

Still, it seemed to offer at least some promise as a potential, low-cost alternative to more the established methods, like Phase Contrast and DIC. 

But, what Secrets does it really hold? And, will it really measure up to all the wild claims made for it? 

Stay tuned to this Blog to find out!  

 * * * * *  

[ UPDATE ] 

The sample unit (shown above) was contained in a fitted wooden box, together with an aperture viewing telescope, a set of three slip-on tops and an adapter ring for the mounting sleeve. An iris diaphragm and swing-out filter holder were attached to the base of the main unit with three small screws, which would allow the iris unit to be rotated, if needed, and then locked into position. 

   

The basic condenser was provided in a European-standard 37.0mm sleeve mounting. Unfortunately, instruments using this size mount are not common in the US and this diameter is a bit to large to fit the JIS-size sleeve mount (36.75mm) which is far more common (e.g: Nikon-S, Olympus BH and CH, etc).  

   

However, included in the set was an expansion sleeve (adapter) which enlarges the Condenser mount size to 39.5mm (the old Leitz/Wild size). Reportedly, there is also an adapter sleeve for 38.75mm mountings (RMS, B&L) but this was not present with the sample tested. 

     

The condenser unit itself appeared to be a conventional 3-lens design, with the third lens provided as a slip-on option. A brightfield top of NA 1.2 ("A 1,2") and a pair of darkfield tops ("A 0,65" and "A 0,8-1-1,2" – as shown above) were included. (The later top presumably provided NA 0.8-1.0 "dry", and 0.8-1.2 when used with oil.) Oddly, there were only two positions in the fitted case for such tops, although a total of three were actually provided. (There were also three slots for filters, but none were included with the sample unit. These were reportedly Blue, Green and Ground glass types.)  

   

By itself (with no top) the condenser appeared to have a NA of approximately 0.45, or so, since it filled the rear aperture of a 20x/0.40 objective but only about 2/3 to 3/4 of the aperture of a 40x/0.65 objective. When the A1,2 top was added, the rear aperture of the 40x/0.65 objective was easily filled, with the condenser iris a bit more than 1/2 open. (Details of the internal optics of the device will be presented in the next update.) 

Still, the main question to be answered remains, "What, if anything, does this thing actually do?" 

And that can only be answered by actual testing…  

* * * * *