Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,926   Posts: 1,556,806   Online: 935
      
Page 1 of 4 1234 LastLast
Results 1 to 10 of 35
  1. #1
    sandermarijn's Avatar
    Join Date
    Oct 2005
    Location
    Leiden, Netherlands
    Shooter
    35mm
    Posts
    770
    Images
    11

    What does this lever do in the EOS mount?

    Anybody know what this lever does?

    Click image for larger version. 

Name:	eos_mount_lever_overview.jpg 
Views:	57 
Size:	72.5 KB 
ID:	52548

    Click image for larger version. 

Name:	eos_mount_lever.jpg 
Views:	57 
Size:	62.1 KB 
ID:	52549

    I thought that the EOS system is fully Electro-Optical, but obviously this lever must be useful for something.

    I have noticed that if you push the lever upwards and simultaneously press the shutter release that the mirror will flip up while the shutter remains closed. Holding the lever in the upwards position and pressing the shutter release once more makes the mirror go down (but the shutter still does not fire).

    Could it be that this feature is there for technicians wanting to get to the front side of the shutter? Or is there a more obvious, picture-taking-related explanation? I've searched the web but nothing's shown up to explain.

    Thanks for any help,
    Sander

  2. #2
    ath
    ath is offline
    ath's Avatar
    Join Date
    Aug 2006
    Location
    Germany
    Shooter
    35mm
    Posts
    890
    I think it just drives a switch and is activated when a lens is mounted.
    Regards,
    Andreas

  3. #3
    sandermarijn's Avatar
    Join Date
    Oct 2005
    Location
    Leiden, Netherlands
    Shooter
    35mm
    Posts
    770
    Images
    11
    And what would the function of that switch be? To let the camera know when a chip-less lens is attached?

    But then why the funny mirror up/shutter closed behaviour?

  4. #4
    flatulent1's Avatar
    Join Date
    Oct 2008
    Location
    Seattle USA
    Shooter
    Multi Format
    Posts
    1,286
    With no lens mounted at all, the camera operates normally.
    With a Zeiss C/Y lens mounted via an adapter, my camera operates normally.
    With a Mamiya 645 lens mounted via an adapter, my camera shuts down and refuses to play along.

    This switch doesn't exist on digital EOS that I'm aware of. Folks selling Mamiya lens adapters on ebay generally say they are compatible with EOS digital, and say nothing about film bodies. One seller linked to a series of photos showing this switch pushed up and a wad of paper placed in the slot as the way to get adapter compatibility with film cameras. I couldn't get it to work for me. And I have no idea what this little switch does.
    Fred Latchaw
    Seattle WA


    I am beginning to resent being referred to as 'half-fast'.
    Whatever that's supposed to mean.

  5. #5
    sandermarijn's Avatar
    Join Date
    Oct 2005
    Location
    Leiden, Netherlands
    Shooter
    35mm
    Posts
    770
    Images
    11
    Ah, interesting. The thing is, I purchased a Leitax adapter for my favourite Leica lens (I have only one anyway), the 35-70/4. All my EOS bodies (I have no digital EOS) refuse to fire (the mirror goes up, no shutter release) with the adapted lens mounted.

    At first I thought of mirror jam against the adapter or the rear element, or the electrical contacts of the camera shorting against the adapter, but then I noticed how the flange of the adapter pushed up this funny little lever. I filed off some of the adapter's flange so that the lever stays put, and all seems well now.

    The question remains though, what is this lever for?

  6. #6
    sandermarijn's Avatar
    Join Date
    Oct 2005
    Location
    Leiden, Netherlands
    Shooter
    35mm
    Posts
    770
    Images
    11
    There is one slightly cryptic remark on the leitax site (http://leitax.com/Leica-lens-for-Canon-cameras.html):

    "Our Leitax mount will trigger the AF switch in 1D series bodies."

    Indeed, the lever/switch is present on the 1Ds also (http://a.img-dpreview.com/reviews/ca...ges/sensor.jpg), although not on e.g. the 5DmkIII (http://www.dpreview.com/reviews/cano...ges/sensor.jpg).

    So, sticking to the Leitax vocabulary, this is an "AF switch". Isn't such a thing on the lenses already? Puzzling.

  7. #7
    ambaker's Avatar
    Join Date
    May 2011
    Location
    Missouri, US
    Shooter
    Multi Format
    Posts
    549
    It was on the earlier EOS bodies. You can stick a bit of paper in there to trigger it. The older bodies want to see it activated. I forget where I found this info, it's been a year or two. But that is the gist of it. The early EF lenses had a lobe on the mount that would press the switch.

  8. #8
    ambaker's Avatar
    Join Date
    May 2011
    Location
    Missouri, US
    Shooter
    Multi Format
    Posts
    549
    Found part of the discussion here....

    http://photography-on-the.net/forum/...h#post12443702

    It's on page 628, if the link does not take you right to it. It turns on the auto focus when an EF lens is mounted.

  9. #9
    sandermarijn's Avatar
    Join Date
    Oct 2005
    Location
    Leiden, Netherlands
    Shooter
    35mm
    Posts
    770
    Images
    11
    Thanks ambaker, that's very useful information. I tried to google for more on this but the search terms I can think of are too generic to yield relevant results.

    My take is that the camera gets confused when the "AF micro switch" (or what you call it) is activated by a lens or mount that doesn't autofocus. The camera decides to lock up, not knowing what to do with the conflicting information. Maybe the camera is waiting for some sort of AF confirmation or feedback that never comes, and thus gets caught in a perpetual loop.

    Advice to self and others: on cameras with the "AF micro switch", do not use non-CPU lenses/adapters that trigger the switch.

  10. #10
    dances_w_clouds's Avatar
    Join Date
    Mar 2008
    Location
    Vancouver B.C. Canada
    Shooter
    Multi Format
    Posts
    1,239
    Images
    44
    I do know the tab that engages that lever on the adapter must be filed down on M-42-EOS for it to work. I use an EOS 3 with a Helios 44-2/58 lens
    Last edited by dances_w_clouds; 06-16-2012 at 09:47 PM. Click to view previous post history.

Page 1 of 4 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin