mamiya C220 focus mis-alignment

Discussion in 'Medium Format' started by fran_ois_courtois, Apr 12, 2005.

  1. Hello, this is my first post on this forum, so please be indulgent !
    My C220 with 80/2.8 systematically "front focusses" (focusses to a
    point closer than the actual subject that appeared sharp in the
    finder). It is very visible on portraits ... Is it possible to correct
    this easily myself? Thank you
     
  2. only reason I can imagin is a problem with the waistlevelfinder or the screen, check if they are proper in place and there isnt a correction lens attached to the magnifying lens.
     
  3. I recall there are some small screws in the viewfinder assembly that can be used for adjustment. They are usually set at the factory and and are glued in place.

    I haven't seen one of these cameras in a while....is it possible to install the screen upside down?

    It sounds like the camera has been tampered with. It shouldn't need adjustment.
     
  4. François,
    I had the same problem with mine when I bought it. Here's what I did to correct it:

    1. I took the focussing screen off and lo and behold, it was not properly shimmed; someone had taken the screen off previously and the shims had fallen off of the screws which attach the screen to the body. I replaced the shims.

    2. To confirm the focus (the hard part). I took a 6x6cm piece of perspex and covered one side in 'invisible' scotch tape (the satin textured stuff). This was a 'cheap focussing screen. I placed the camera on a tripod and placed a page of newspaper, well lit, on the wall about 30cm away from the camera. Everything was perfectly level and measured. I opened the back of the camera and placed the focussing screen onto the film plane. With all of this in place, I focussed the camera in the usual way and then, with a loupe, ensured that the image was in focus on my perspex focussing screen.

    3. If everything is now focussed, great. If not, you might have to check the shims on the focussing screen again.

    Hope that this helps,
    Kent
     
  5. Mag, what do you mean by "correction lens attached to the magnifying lens"?<p>Kevin, i do not think anything is "upside down", this camera has just been bought but is in pristine condition, probably never been used before. Sorry for my english, but what does "tampered" mean?<p>Kent, what is a "schims"? Is it a sort of spacer that uplift the focussing screen to adjust focus? Is it not risky to unscrew the focussing screen?<p>To ensure focus is ok on the perspex, surely you need to fire the shutter? I cannot do this while the back is open ... and if I could, do you use the bulb setting to open the aperture?<p>Anyway, thank you very much for helping me, I'm a newbie
     
  6. in your waist level finder you have a fold out magnifying loupe, to this maybe a diopter correction loupe is attached.
     
  7. http://www.macuserforums.com/webx?14@27.ffJHaLiCp70.2@.ee707e6

    you can post your question here, there are Mamiya technicans
     
  8. Check that both 'viewing lens' and 'taking lens' are aligned..
     
  9. I would first test it with another lens. The one you have may have been dropped, may have had the lens shimmed incorrectly when serviced. If the taking lens and the viewing lens are not focused to the same spot, miss focusing can occur.

    Assuming the different lens exhibits the same phenominum, I would make sure the hold down bail is holding the lensboard in the correct secured space. I have never seen it on an 80mm lens, but I have on a 180mm. The weight of the lens made the whole lens assembly just a bit loose.

    Finally do the pull the screen method and add (or subtract) shims. More an issue on the C33 and C330s as those screens are meant to be swapped, but someone could have been messing with your permanent C220 viewing screen. Or replaced it altogether with an inappropriate one.

    tim in san jose
     

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