The OM Zuiko MC 24-40mm f4 Info Page

I purchased this lens through a Japanese auction site. As soon as I saw the listing, my heart started to race. As I searched the internet and other sources for information, and as I continued to find absolutely no information, I became more and more excited. It came down to an all out bidding battle between myself and one other bidder. I won, quite by accident, by one dollar. I had decided it was my highest bid and then before I knew it the auction was over and I had actually won it.

Since then, I have discovered some things about it. Other things remain mysteries. My quest is to solve the mysteries and, in the process, tell a story of historical interest for all lovers of cameras, and especially lovers of the Olympus OM System.

What I Know So Far:

Jihei Nakagawa

I estimate, based on the dates in the patent mentioned above, that the lens was designed some time around 1977. It was designed by Jihei Nakagawa while employed by Olympus Japan. Here is what Nakagawa-san had to say about this lens design (from the patent):


To save you the trouble, I'll include the definition of "epoch-making": So significant and momentous as to characterize the beginning of a period.

I can confirm that, despite the low contrast due to haze, the resolution and other imaging characteristics of this lens are superb, especially for a compact zoom and especially for that time period.

So, it is apparent that he had very high hopes for this lens and its place not only in the OM line, but its place in the history of zoom lens design. Hopefully my research will answer the question; Why?... Why didn't the lens make it onto the production line? Was this a factor in Nakagawa-san's departure from Olympus? So many questions...
 
Jihei Nakagawa eventually went to work for Sigma. While he was there, he "invented an innovative four group zoom lens, in which group 1 is linked to group 3, and group 2 is linked with group 4; lens group1/3 and lens group 2/4 can move relative to each other while mantaining the fixed distance between 1/3 and between 2/4. His design greatly extended the zoom range of zoom lens, and makes [choice] of glass and optimization of abberration easier."** I find this fact very intriguing, because Nakagawa-san describes a similar system of lens group movement in the patent for this lens design. Nakagawa-san has been published multiple times in optical design journals since then. I have contacted Sigma and they have responded:

Thank you for our e-mail.

Mr. Nakagawa was retired and he is no longer at Sigma.
We regret however there is no further information about him.

Sincerely,
Sigma Corporation of America

Olympus Japan

I have also contacted Olympus Japan and requested information about this lens. Their first reply was:

 I replied, confirming the model number with a series of photos (you see some of them above). The response:

Thank you for your sending us the pictures of your lens.

We checked our record again.
Unfortunately, there is no record that we put such lens on our production line.
There is no record that we sold such lens either.

Since all the people who were concerned with 
the production of OM lenses have already retired, 
no one knows about this lens in our company.

There are not manuals for products that were neither produced nor sold.

We are sorry that we cannot be more helpful about this matter.

Thank you for your understanding.

Best regards,

S. Sato
Customer Support Center
OLYMPUS IMAGING CORP. Tokyo, Japan

Once I recieved this letter, I became convinced that this gem that I own is, in fact, an extremely rare prototype of one of the first two "embodiments" of the design presented in the patent (the other two embodiments are not 24-40mm). It is my opinion that this lens is a prototype of embodiment 1. While both embodiments 1 and 2 are 24-40mm f4 lenses, one difference between them is that embodiment 1 has cemented elements in the front group. This lens has some haze, and I have inspected the curvature of the hazed surfaces. They seem to correspond with the surfaces that are cemented in embodiment 1. Thus, I believe the haze on these surfaces is due to element separation. I can fairly confidently say that the lens block diagram looks like this (please forgive my lack of skill with my children's coloured pencils):


Update: I have managed to repair the filter ring dent, which has allowed me to (easily) remove the front assembly of elements (the first three). Using a flashlight, I have confirmed that the haze is, in fact, in the front group. I am assuming it is the cement between elements 2 and 3 that is causing the haze, but I do not know for sure. The rest of the elements seem clear. I can also confirm, with much more certainty, that the lens block diagram pictured above is that of this lens. It is easy for me to see that there is a very simple couplet of small elements (elements 4 and 5) just in front of the aperture blades, and then a much more powerful, denser series of elements between the aperture blades and the back of the lens. I will now begin investigating the possibility of having elements 2 and 3 separated and then re-cemented.

More information about the lens, its performance, its story, etc. coming soon....

** Source of quote: http://photo.net/leica-rangefinders-forum/002kFP