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PostPosted: Thu Apr 21, 2022 4:47 pm    Post subject: Reply with quote
Honestly, I have so many 50mm lenses that at this point it is time to cull the herd instead of acquiring more. It's also not clear that the m42 has the same optics or coatings.


PostPosted: Thu Apr 21, 2022 5:18 pm    Post subject: Reply with quote
cbass wrote:
Honestly, I have so many 50mm lenses that at this point it is time to cull the herd instead of acquiring more. It's also not clear that the m42 has the same optics or coatings.


I'm pretty sure it's a totally different lens. Coatings of the E(F) series are by the way nothing to write home about, despite being from the eighties.


PostPosted: Thu Apr 21, 2022 5:55 pm    Post subject: Reply with quote
The Auto-Mamiya Sekor 50mm F2 and Mamiya-Sekor E are both 6/4 double gauss designs if LensDB is correct. The diagrams are a bit different though.

Auto


E



I also found a Diagram for the 50/1.4 It seems it is really a 7/6 design and not 7/5 like the Tomioka/Cosina 55/1.4's



PostPosted: Sat Apr 23, 2022 9:58 pm    Post subject: Reply with quote
Here's an image of the rare beast - mounted onto the equally rare Mamiya ZE-X (introduced 1982) camera:



The ZE-X was a multi-mode SLR from the early 1980s, and its design was very clean and pure:

* Shutter speed wheel - set it to "A", and you have aperture priority automatic exposure
* Aperture ring (on each lens) - set it to the white button, and you have shutter priority automatic exposure
* Set both shutter speed as well as aperture to "automatic", and you have program mode automatic exposure



The ZE-X probably was the first SLR to have a variable program mode - depending on the focal length of the lens attached, the program mode did result in different shutter sped / aperture combinations. That was pretty awesome for a 1982 SLR! Of course also the warning "beep" for camera shake was dependent on the focal length of the lens.

Even more interesting were the Sekor EF lenses, specifically introduced for the ZE-X. Other than the EF 1.4/50mm, there was an EF 1.7/50mm, an EF 2.8/35mm, and an EF 2.8/135mm as well. Unlike the "ordinary" Sekor E lenses, these EF lenses had additional electronic contacts for distance encoding, providing the ZE-X with information for dedicated electronic flashes. There was even a small switch on the base of each Sekor EF lens, allowing to turn off the system!

Looking at all the features of the Mamiya ZE-X it may be no surprise that Mamiya had a working "ZF" prototype SLR with autofocus as early as 1983. The Minolta AF system was presented in 1985 ...

S


PostPosted: Sun Apr 24, 2022 3:18 am    Post subject: Reply with quote
How did it meter for ttl/program flash?

It looks like 4 contacts on the hot shoe, unless the forward one is a retainer screw.

I think it was minolta first out the gate with off the film plane ttl/program flash in the X-700 from roughly the same time period....

-D.S.


PostPosted: Sun Apr 24, 2022 12:17 pm    Post subject: Reply with quote
Doc Sharptail wrote:
How did it meter for ttl/program flash?

It looks like 4 contacts on the hot shoe, unless the forward one is a retainer screw.

I think it was minolta first out the gate with off the film plane ttl/program flash in the X-700 from roughly the same time period....

-D.S.


Indeed Minolta, but the first TTL flash metering was introduced in the X-500 (X-570 in the U.S.) and not the X-700.


PostPosted: Sun Apr 24, 2022 7:35 pm    Post subject: Reply with quote
Doc Sharptail wrote:
How did it meter for ttl/program flash?

It's not a TTL system! The distance set on the lens translates to a suitable aperture, automatically generated by the camera (remember: the aperture is controlled by the camera, and NOT by the aperture ring on the lens!). The dedicated MZ-36R flash is used at 1/4 power (GN 18 ) at distances from 1.1m to 13m (with the camera selecting f16 to f1.4); at 13m the flash changes to full power and f2.8, and at even largere distances the camera goes to f2 and f1.4 again.

Doc Sharptail wrote:
It looks like 4 contacts on the hot shoe, unless the forward one is a retainer screw.

Four contacts indeed, but not TTL information!

Doc Sharptail wrote:

I think it was minolta first out the gate with off the film plane ttl/program flash in the X-700 from roughly the same time period....

-D.S.

No. Olympus was first (1975 with its OM-2), but based on a Minolta patent!

tb_a wrote:

Indeed Minolta, but the first TTL flash metering was introduced in the X-500 (X-570 in the U.S.) and not the X-700.

No. The X-700 did have TTL flash metering, and it was introduced in 1981. The X-500 / X-570 came in 1983.

S


PostPosted: Sun Apr 24, 2022 8:02 pm    Post subject: Reply with quote
stevemark wrote:

No. The X-700 did have TTL flash metering, and it was introduced in 1981. The X-500 / X-570 came in 1983.


You're right, I mixed that up with some other features which are better introduced/improved in the X-500 model.
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