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Re: [OM] 50mm Lens Versions (again)

Subject: Re: [OM] 50mm Lens Versions (again)
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Wed, 17 Jan 2001 21:25:17 +0000
In the not so recent past, some questions were raised about formulation changes in the 50/1.4 "MC" lenses related to their serial numbers. According to Gary Reese, at some point the formulation changed from only some of the groups being multi-coated to all of them at or over the 1,000,000 serial number. It is also apparent that at or over 1,100,000 the "MC" marking was dropped from the lens ring. The block most in question about whether it is before or after the reformulation that multi-coats all the groups falls in the 1,000,000 to 1,100,000 serial number block.

I now have three multi-coated 50/1.4's within three different serial number blocks. The first is 789,###, the second 1,05#,###, and the third is 1,11#,###. Following are my conclusions after examining all three:

789,### Zuiko MC:
Through the front element, it shows purplish reflections with some green ones internally. Through the rear element, it only shows purplish reflections. The nature of the colors in the reflections is clearly different between examination through the front and rear elements.

1,05#,### Zuiko MC:
Through the front element, it clearly shows green and purplish reflections from a number of groups. Through the rear element, it shows the same type of reflections as through the front element.

1,11#,### Zuiko:
Through the front element, it clearly shows green and purplish reflections from a number of groups. Through the rear element, it shows the same type of reflections as the front element.

Conclusions:
1. There was indeed a formulation change related to the multi-coating between S/N 789,### and 1,05#,### for the 50/1.4 lenses.

2. The "Zuiko MC" marking remained unchanged at the time of the formulation change. When exactly this occurred cannot be determined, but is somewhere between the first two S/N's. A reset to S/N 1,000,000 has logic to it, and this examination does not refute it.

Gary Reese:
Was your citing of this S/N break a hypothosis based on observation, or is there reliable documentation of some type to support it?

3. At some point later the "MC" was dropped from the "Zuiko MC" marking leaving only "Zuiko" on the lens ring. There is no correlation between the multi-coating formulation change and the marking change. Thus far, only those with S/N's over 1,100,000 are documented in the information I've found as being marked this way.

4. Whether a lens is marked "Zuiko MC" or "Zuiko" (but _not_ "G.Zuiko") is not a reliable test for determining its formulation. A serial number of 1,000,000 or higher, not 1,100,000 or higher, is more reliable in finding the newer multi-coating formulation lenses as it is now apparent there are some with S/N over 1,000,000, but under 1,100,000, with "Zuiko MC" markings.

5. Which formulation a particular 50/1.4 has is more accurately determined by examining the color reflections through both the front and rear elements. My guess is the first MC formulation will only show MC related reflections (i.e. green) from examination through the front element, and will only show single-coating type reflections through the rear element. The second formulation shows MC type reflections through both the front and rear elements.

6. All of the above presume the lens ring (and therefore the S/N) has not been swapped or replaced.

-- John

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