Please explain difference between AE and MM lenses

[Guest]

I have converted Planar 135F2 and Distagon 28F2
The differnce about Ae Lens and MM lens is e little metal part on the base of lens.
It activates a switch on camera near lens attach.
If you install (in the just position)in Ae lens this little metal part, it become MM lens.
You can obtain the same thing using a little part of a toothpick to stop a little switch (near lens attach)at the end of his limit.
This is possible with 159 MM and all bodies made after.

 

[Guest]

Hello Eugenio,

does this really work?!

As Contax and Zeiss tells a conversion is not possible (Cause it would be much too expensive). They say that MM lenses are using a different diaphragm mechanism which is much smoother to operate than the one in AE lenses.
I moved the diphragm lever on my Tessar 2.8/45 AE and on my Distagon 1.4/35 MM with a finger. The one on the MM lens is moving much smoother and easier than on the AE lens which is quite stiff.

You told about a overexposure before. Maybe this is a result of the stiffer mechanism on the AE lens. So camera can't set aperture correct.

Matthias

 

[Guest]

It definitely doesn't work. The AE Spring-Blade Mechanics is too heavy and not linearly closing down. At the time the AE design was made, it was only important to close the blades at all, without taking care of "intermediate positions".

Doing what was suggsted generates a very big likelyhood for wrong (mostly over-) exposure.

As said, the MM Diaphragm-blades are much smoother designed (to close faster and with less force) and they are designed to give a defined (most likely linear) closing curve so that the camera can control the actual value.

 

[Guest]

Hi there,

Can anyone tell me if the ST or RX require the MM lens to access all functions?

 

[Guest]

Hello Michael,

both cameras are only working in manual and aperture priority mode with AE lenses. For time priority and program mode a MM lens is needed.
MM lenses could be recognized by the green shortest f-number and a little pin on the lower left side of the lens (look at it from behind)

Matthias

 

[Guest]

with the yashica 108 and 109 mp-cameras you can use non MM-zeiss in program mode too. but the contax mm-combination is quicker concerning the time between measuring and exposure. btw: sigma made mm-lenses with c/y-mount! i have seen this in an older prospectus.

 

[Guest]

Hello,

a camera doesn't always expose the film with the time/f-stop combination shown in the viewfinder. Sometimes a 673 1/s is needed or a f stop of 7.3.
As I know Contax-cameras really set the diaphragm blades to any value which is needet while Yashice can only set the values given on the Aperture ring. The "rest" is done by setting the shutter to another value than selected in TV-mode.
So Contax cameras need lenses which can be set to each aperture value for TV and Program mode.
This can also be possible with lenses of third party manufacturers.

Matthias

 

[Guest]

Thanks Matthias for your help. I have a 50/ 1.4 CZ lens now. However, the f16 figure is in white, not green. The CZ box indicates that this is a Multimode lens. How can I be sure this is an MM lens or have the boxes been switched. I know you have referred to a small pin on the lower left hand side and I can see (at about 8 o'clock) a small lever that sticks out from the back of the lens slightly. There is also a lever near the 12 o'clock position, but this doesn't stick out as far. Have any 50/1.4 MM lenses been made without a green painted f16?

 

[Guest]

Hello Michael,

in my opinion someone switched the box. It's a unique feature of the MM lenses to have the shortest f-stop printed on in green.
A picture says more than words. So I took out my digital p&s and took some pictures of the pin and the corresponding switch on my Contax for you. The pin may look a bit different on your Planar 1.4/50mm (If there's one) than on my Planar 1.4/85mm 'cause of the smaller diameter.

I numbered all the connecting parts on the camera and the lens mount:
1 Automatic diaphragm coupler
2 coupler for largest aperture setting
3 aperture linkage lever
4 mm (program + TV) coupling lever

Hope this helps you.

Matthias

 

[Guest]

I have a 50/ 1.4 CZ lens now. However,> the f16 figure is in white, not green. The CZ box indicates that this > is a Multimode lens. How can I be sure this is an MM lens or have the> boxes been switched. I know you have referred to a small pin on the> lower left hand side

Another difference between the AE and MM lenses is the shape of the diaphragm opening - the older AE lenses have a sort of "sawtooth"shape when you stop them down a bit , the MM's opening is "rounder"....... Steve