Checking to see is aperture is functioning

Discussion in 'Camera Building, Repairs & Modification' started by Llamarama, Aug 6, 2013.

  1. Llamarama

    Llamarama Member

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    Hello everyone, I recently found my dad's old Praktica MTL5 in my loft.

    I've been messing around with it and everything seems to be working, but i'm not sure about the aparture. When I remove the lens (Tessar 2.8/50 Carl Zeiss Jena DDR) the aparture appears to be fully open, no matter which setting I have it set to. The manual states that I should be able to adjust the aparture when it is set to manual mode and see the result through the view finder, however it looks the same.

    I haven't loaded a film into it yet. Is there any way of checking to see if they are stuck and if they are, how would i go about un-sticking them?

    Many thanks - Mike
     
  2. ann

    ann Subscriber

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    Did you fire the shutter, the aperture stays open until the shutter is fired and then it should stop down.?

    Just open the back of the camera (without film) and run some test.
     
  3. Llamarama

    Llamarama Member

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    Oh dear, set the shutter speed to mode B (Open as long as shutters depressed) and it looks like they are jammed. Any way of coaxing them out creatly appreciated as the optics are absolutely spotless.
     
  4. David Lyga

    David Lyga Subscriber

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    Mike, set the aperture to f22 (or f16 if this is the smallest). Then, remove lens (unscrew it) from body. Then press the tiny pin on the back with your finger. The blades should stop down. If not, there might be oil on the blades. Removing this would involve removing all the glass elements. - David Lyga
     
  5. Dali

    Dali Subscriber

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    I think there is an Auto / Manual switch on the lens to set the diaphragm on one or the other mode. In Manual mode, you should be able to close the diaphragm with the aperture ring. In Auto mode, like David said, you have to puch the pin close to the mount to get the same result.