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The "Mamiya" SLR - the very first Mamiya Single Le
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PostPosted: Tue Jul 02, 2019 9:36 pm    Post subject: The "Mamiya" SLR - the very first Mamiya Single Le Reply with quote
Yesterday i got a sample of the the very first Mamiya SLR, simply called "Mamiya". There is very little information found on-line; it is said to be from 1960. The camera has an Exakta bayonet (with a Sekor F. C. 1.7/58mm lens attached). Its shutter goes from 1 s to 1/500 s, the aperture on the 58mm lens from f1.7 to f22.

My sample has a stuck shutter, and the lens aperture is stuck open as well. Obviously - long time ago - someone tried to fix it: A few "spare" parts such as small screws and other "minor" parts were glued onto the inside of the camera (where one would load the film)!

More images will follow.

Does someone know more about this beast?





Stephan


PostPosted: Tue Jul 02, 2019 9:52 pm    Post subject: Reply with quote
Cool find, I've never seen the camera.


PostPosted: Tue Jul 02, 2019 10:44 pm    Post subject: Reply with quote
You can see.

http://herron.50megs.com/prismat.htm


PostPosted: Sun Jul 07, 2019 8:27 pm    Post subject: Reply with quote
Here are two more images from the Mamiya SLR:




Stephan


PostPosted: Mon Jul 08, 2019 9:53 am    Post subject: Reply with quote
With an 58mm 1.7 6 element lens with good sharpness, 10 blades?. https://www.pentaxforums.com/userreviews/mamiya-sekor-58mm-f-1-7.html The last version of it was in 42mm mount for the Mamiya CWP/CP SLR model. I presume it is a double gauss but could not find a lens diagram. Mamiya had odd optical schemes in some early rangefinder models but probably not in the early SLRs.

Ernst Dinkla


PostPosted: Mon Jul 08, 2019 6:35 pm    Post subject: Reply with quote
Ernst Dinkla wrote:
With an 58mm 1.7 6 element lens with good sharpness, 10 blades?. https://www.pentaxforums.com/userreviews/mamiya-sekor-58mm-f-1-7.html The last version of it was in 42mm mount for the Mamiya CWP/CP SLR model. I presume it is a double gauss but could not find a lens diagram. Mamiya had odd optical schemes in some early rangefinder models but probably not in the early SLRs.
Ernst Dinkla


Before being able to test it, i had to slightly adjust infinity. Comparing the Mamiya side-by-side with the last computation of the Topcor RE 1.8/58mm (certainly one of the better normal lenses from that time) the Mamiya has as little CAs, but slightly more astigmatism. It seems the Mamiya has a thoriated front lens which is rather unusual.

Stephan

EDIT my Mamyia Sekor F.C. 1.7/58mm has seven aperture blades. Obviously one is missing, so the correct number would be eight blades!


PostPosted: Mon Jul 15, 2019 10:10 pm    Post subject: Reply with quote
Mamiya made some of the early Canon cameras. A good pedigree


PostPosted: Tue Jul 16, 2019 11:40 am    Post subject: Reply with quote
philslizzy wrote:
Mamiya made some of the early Canon cameras. A good pedigree


Are you sure? I only know of some Nikon and, maybe, Ricoh SLRs made by Mamiya, namely the Nikkorex F:
https://www.cameraquest.com/nfrex.htm

Some of the later Mamyia Prismat SLRs were equipped with Canon lenses, however.

Stephan


PostPosted: Thu Jul 09, 2020 12:23 pm    Post subject: Reply with quote
Some people seem to have difficulties with the correct operation of the Mamiya-Sekor F.C. 1:1.7 f=55mm aperture mechanism on modern mirrorless cameras - here's the instruction:

1) Cock the (silver colored) aperture mechanism on the left side of the lens ("left" when looking through the viewfinder of the camera)



2) Adjust the aperture ring to the desired value by first pushing the small silver colored button on the lower side of the aperture ring and then turning the aperture ring



3) Take the lens off the camera and push the small plug on the back side (!!) of the aperture lever; it will close the aperture to the desired value
EDIT: Now the lens will work like a fully manual lens, i. e. you can open and close the aperture manually by turning the aperture ring - unless you completely open the aperture (f1.7)!! When you open the aperture completely, it will remain open and you have to start with 1) again ...



4) If you want to re-open the aperture, just start with 1) again!

Stephan

Last edited by stevemark on Fri Jul 10, 2020 12:51 pm; edited 2 times in total


PostPosted: Thu Jul 09, 2020 2:27 pm    Post subject: Reply with quote
I had the Canon f1.8 50mm Exakta mount lens for the Mamiya SLR. Straw coloured single coating, poor contrast, but quite sharp. I think it's the same as the Canomatic version.


PostPosted: Fri Jul 10, 2020 3:42 am    Post subject: Reply with quote
stevemark wrote:
Some people seem to have difficulties with the correct operation of the Mamiya-Sekor F.C. 1:1.7 f=55mm aperture mechanism on modern mirrorless cameras - here's the instruction:

1) Cock the (silver colored) aperture mechanism on the left side of the lens ("left" when looking through the viewfinder of the camera)
2) Adjust the aperture ring to the desired value by first pushing the small silver colored button on the lower side of the aperture ring and then turning the aperture ring
3) Take the lens off the camera and push the small plug on the back side (!!) of the aperture lever; it will close the aperture to the desired value
4) If you want to re-open the aperture, just start with 1) again!

Stephan


Thanks very much Stephan for the detailed information. You know what, the first time I checked the back of my lens, I noticed the tab, but didn't pay attention. When I saw your instructions, I turned the lens back and found the tab. It is hidden inside the mount, I suspect it is broken. It hid even slightly below the edge of the rear element, I had to use some blade to move it. Is yours like this, or yours sticks out of the mount, like a regular tab in many other lenses.

If the tab thing works, do you mean every time I change the aperture I have to put the lens on the camera and take it off and mount it again to shoot?


PostPosted: Fri Jul 10, 2020 1:23 pm    Post subject: Reply with quote
vivaldibow wrote:

Thanks very much Stephan for the detailed information. You know what, the first time I checked the back of my lens, I noticed the tab, but didn't pay attention. When I saw your instructions, I turned the lens back and found the tab. It is hidden inside the mount, I suspect it is broken. It hid even slightly below the edge of the rear element, I had to use some blade to move it. Is yours like this, or yours sticks out of the mount, like a regular tab in many other lenses.

No, I was not talking about that tab, even though my lens does have this one as well! The tab you're talking about is somehow connected to the aperture (and not the aperture ring!). Obviously it was designed to transmit some information about the real position of the aperture to the camera body. Strangely enough, my Mamiya "SLR" does not have a "receiving" pin to read that information. Probably it was incorporated to the lens in anticipation of later bodies with TTL measuring ?!?

vivaldibow wrote:

If the tab thing works, do you mean every time I change the aperture I have to put the lens on the camera and take it off and mount it again to shoot?

No. Check the images above ... i just inserted them to make things clear!

S


PostPosted: Fri Jul 10, 2020 6:21 pm    Post subject: Reply with quote
stevemark wrote:

No, I was not talking about that tab, even though my lens does have this one as well! The tab you're talking about is somehow connected to the aperture (and not the aperture ring!). Obviously it was designed to transmit some information about the real position of the aperture to the camera body. Strangely enough, my Mamiya "SLR" does not have a "receiving" pin to read that information. Probably it was incorporated to the lens in anticipation of later bodies with TTL measuring ?!?

No. Check the images above ... i just inserted them to make things clear!

S


Appreciate your photo illustrations. I've played with the vertical push pin in the arm before and nothing happened. And that's why I thought you meant the little pin at the lens rear. My Carl Zeiss Jena 35mm f/2.8 has a similar mechanism (an arm with a push pin) and it worked to stop the aperture (DOF preview button).


PostPosted: Fri Jul 10, 2020 7:10 pm    Post subject: Reply with quote
vivaldibow wrote:

Appreciate your photo illustrations. I've played with the vertical push pin in the arm before and nothing happened.


If in fact you did push as indicated by the yellow arrow, and nothing happened (aperture ring must be set e. g. to f8, of course), then the aperture obviously is stuck ...

S



PostPosted: Fri Jul 10, 2020 8:27 pm    Post subject: Reply with quote
stevemark wrote:
vivaldibow wrote:

Appreciate your photo illustrations. I've played with the vertical push pin in the arm before and nothing happened.


If in fact you did push as indicated by the yellow arrow, and nothing happened (aperture ring must be set e. g. to f8, of course), then the aperture obviously is stuck ...

S



This is my intial conclusion: the aperture is stuck. I am going to see how the vertical movement of the push pin transfers to horizontal movement of the aperture blades in this arm.


PostPosted: Sat Jul 11, 2020 7:05 pm    Post subject: Reply with quote
I managed to make it work.

Once it is fully open, to close down, say 2.8, first turn the aperture ring to set the value then push the pin up, blades will close. For f value other than 1.7, just turn the aperture ring.

The thing is, the arm is a little short. With the Ext to NEX adapter, the pin hits against the top rim so it can't be mounted. I am so eager to use this lens, but will need to spend some time to tweak the adapter.


PostPosted: Sat Jul 11, 2020 7:28 pm    Post subject: Reply with quote
vivaldibow wrote:
I managed to make it work.

Once it is fully open, to close down, say 2.8, first turn the aperture ring to set the value then push the pin up, blades will close. For f value other than 1.7, just turn the aperture ring.


Exactly as I said ... congratulations Wink

S


PostPosted: Sat Jul 11, 2020 9:05 pm    Post subject: Reply with quote
stevemark wrote:
vivaldibow wrote:
I managed to make it work.

Once it is fully open, to close down, say 2.8, first turn the aperture ring to set the value then push the pin up, blades will close. For f value other than 1.7, just turn the aperture ring.


Exactly as I said ... congratulations Wink

S


Thanks. But there seems no need to cock the side tab, as illustrated in your first step.

Another piece of information: this Exakta mount 58mm f/1.7 is not radioactive. I measured.


PostPosted: Tue Jul 14, 2020 10:26 am    Post subject: Reply with quote
vivaldibow wrote:
stevemark wrote:
vivaldibow wrote:
I managed to make it work.

Once it is fully open, to close down, say 2.8, first turn the aperture ring to set the value then push the pin up, blades will close. For f value other than 1.7, just turn the aperture ring.


Exactly as I said ... congratulations Wink

S


Thanks. But there seems no need to cock the side tab, as illustrated in your first step.

Another piece of information: this Exakta mount 58mm f/1.7 is not radioactive. I measured.


That's an interesting information, since it confirms that this lens has a different optical construction than the later M42 variants (which look also quite different)! Thank you!!

S


PostPosted: Wed Jul 15, 2020 5:57 pm    Post subject: Reply with quote
stevemark wrote:
vivaldibow wrote:


Another piece of information: this Exakta mount 58mm f/1.7 is not radioactive. I measured.


That's an interesting information, since it confirms that this lens has a different optical construction than the later M42 variants (which look also quite different)! Thank you!!

S


From a youtube video, the guy said his lens is radioactive and he didn't show the mount. I guess it was M42. Another piece of information from the internet says M42 version is radioactive.

https://lenslegend.com/mamiya-sekor-58mm-f1-7-lens-review/

Interestingly enough, the M42 version has 10 blades, while the Exakta version (your copy and mine) only has fewer blades (I didn't count mine). Yesterday when I searched on the internet, but I couldn't locate the link now. If my memory serves me well, the webpage shows another Exakta version with 10 blades and the infinity mark is also a yellow triangle (but I don't remember if it is upside down or not).
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