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Using a Pentax screw mount lens on a Contax 167MT

G

Guest

I want to use a telephoto lens with a M42 screw mount on the 167MT. The lens aperture is f8 throughout. I have a simple metal adaptor from M42 to C/Y.

Is there any way the 167 body can be told the aperture is set to f8 and then have the body automatically set the correct shutter speed?

Thanks etc
 
G

Guest

Hello,

think you've to use the lens in manual mode and stop down to f8 before exposure. This is the way my T2-mount 300 mm lens works.
The camera won't show you the correct aperture in the viewfinder (I guess it'll show "1.2"), but exposure will be ok.

Matthias
 
G

Guest

Hello,

yes, it's working correctly, except for the aperture (which will always be indicated as 1.2). You have to stop down the lens manually and measure stopped down.

Matthias
 
G

Guest

BTW, I noticed that the distance scale is shifted when a M42 lens is used with a C/Y adaptor (by Hama). For ex&le, to focus 50 mm lens (Zenitar-M) at infinity, I have to set it to 15m. If I rotate it further to infinity sign on the scale, image is blurred.

Kirill.
 
G

Guest

Hello Kirill,

> BTW, I noticed that the distance scale is shifted when a M42 lens is
> used with a C/Y adaptor (by Hama). For ex&le, to focus 50 mm lens
> (Zenitar-M) at infinity, I have to set it to 15m. If I rotate it
> further to infinity sign on the scale, image is blurred.

this has got to do with the flange focal length which is the distance from the mounting flange of the lens to the image or film plane. So you're able to focus your lens behind infinity. This may have two reasons:
-The adaptor hasn't got the right dimension for the flange focal length. So you'll find this effect with each lens used with it.
-The lens hasn't got the right dimension for the flange focal length. Try another lens. If the effect doesn't appear you'll know where this comes from.
Be happy that the effect isn't the other direction. Think of you couldn't focus to infinity...
By the way: the flange focal length is the same for M42 and C/Y mount: 45.5 mm.

Matthias
 
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