WHY won't Nikon meter with old lenses?

Discussion in 'Digital Photography' started by Guest, May 4, 2005.

  1. Guest

    Guest Guest

    I've got a friend interested in getting a DSLR, and he's waffling between the
    Canon 350, Nikon D70, or Pentax *ist-DS. He's a lot like me... interested in
    tinkering with different lenses on the cheap. I've been playing with some old
    screwmount lenses on my *ist-DS and find it a lot of fun to see what I can do for very
    little money on glass. I know a fair bit about the K-mount and M42 Pentax stuff, but
    not much about the other two brands.

    In particular, Nikon lenses from way be to antiquity alegedly can be mounted
    to the newest DSLR's. I've heard of pre-AI lenses needing a modification to prevent
    damage, but it looks like something that can be done cheaply by people who've done it,
    or carefully by oneself. My question is on the metering. Is it a purely marketing
    reason why they disallowed even stop-down metering on the D70 et al? I can see if
    there's a mechanical linkage missing to stop down an older otherwise autoaperture
    lens, but if it still uses the same mechanical connection it's extremely
    short-sighted. At least the Pentax has a stopdown-meter-release mode to use non-A
    glass.

    Just wondering if there's an actual technical limitation or if it's just
    marketing "genius."

    -Cory

    --

    *************************************************************************
    * Cory Papenfuss *
    * Electrical Engineering candidate Ph.D. graduate student *
    * Virginia Polytechnic Institute and State University *
    *************************************************************************
     
    Guest, May 4, 2005
    #1
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  2. I'm sort of in the same situation... with an expanding collection of older
    lenses.
    I think the restriction has <allegedly> something to do with the matrix
    metering taking distance info into account when deciding what subject
    category to go for.

    In reality I guess it's misplaced marketing genius - as a result, I mainly
    use Canon.
     
    Malcolm Stewart, May 4, 2005
    #2
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  3. Guest

    Jim Guest

    Money. Getting the pre-AI or AI-S lenses to work requires lots and lots and
    lots of mechanical parts which make the cameras more expensive. By the way,
    pre-AI lenses can't be mounted on the N series film cameras, so the loss of
    usefulness of pre-AI lenses is nothing new.
    As for the AI-S lenses, they work quite well on my F3.
    Jim
     
    Jim, May 4, 2005
    #3
  4. Guest

    Paul Furman Guest




    Are you sure it doesn't meter or just that it can't set aperture. I'd
    think you could put it in manual & see the +- slider thingy in the
    viewfinder.
     
    Paul Furman, May 4, 2005
    #4
  5. Guest

    Guest Guest

    : > Just wondering if there's an actual technical limitation or if it's just
    : > marketing "genius."
    : >
    : > -Cory

    I was kidding on the "genius" part, BTW. Probably typical situation of
    engineering and marketing not getting along.


    : Are you sure it doesn't meter or just that it can't set aperture. I'd
    : think you could put it in manual & see the +- slider thingy in the
    : viewfinder.

    All I know is what I've read online. Basically, there's the possibility of
    physical damage in some cases, but supposedly any pre-AI lens won't meter. I can't
    comprehend the alphabet soup of the lens/body standards for Nikon, which certainly
    doesn't help. If I owned one, I might be more interested.

    I can understand the lack of mechanical coupling for cost reasons, but I'm
    still wondering why it can't be operated stop-down. Matrix metering doesn't have to
    work, and open-aperture metering doesn't need to work necessarily. Does the body lack
    the physical linkage to stop down the aperture? If not, I see no reason (other than
    marketing) to have the feature not work.... at least in some degraded mode.

    -Cory


    *************************************************************************
    * Cory Papenfuss *
    * Electrical Engineering candidate Ph.D. graduate student *
    * Virginia Polytechnic Institute and State University *
    *************************************************************************
     
    Guest, May 4, 2005
    #5
  6. Guest

    Paul Rubin Guest

    It's not just that it can't SET the aperture, it also can't READ the
    aperture. It has no way to know if you've stopped the lens down. The
    camera has no mechanical coupling to the aperture ring, so turning the
    ring sends no information to the camera.

    Maybe they could have programmed it to support stop-down metering, or
    maybe that would have confused people.

    A reasonable fix might be to jazz up the histogram function, so it
    could tell you the whole scene was overexposed by 0.7 stops or
    whatever, and you'd make an adjustment. It would also be nice to be
    able to get histograms or exposure analysis on selected parts of the
    image using the directional pushbuttons.
     
    Paul Rubin, May 4, 2005
    #6
  7. Guest

    Frederick Guest

    http://home.carolina.rr.com/headshots/Nikonhome.htm
    Some MF lenses can be modified.
    Many wouldn't be worth modifying anyway, as AF versions with the same
    glass are available second hand cheaply, not all Nikon glass is good, as
    a general rule new zoom lenses are in a class above old ones, and in
    some cases asian collectors will buy your old MF nikkor glass at good
    prices in the belief that they they are investing in collectables.
     
    Frederick, May 4, 2005
    #7
  8. Guest

    Sheldon Guest

    : Are you sure it doesn't meter or just that it can't set aperture. I'd
    No, you can put it in manual, but you will not see any exposure settings
    whatsoever. Just shutter speed, and in some cases focus lock.
    AI lenses will not meter, and pre AI lenses must be converted to AI or they
    will ruin the camera. Has to do with the aperture ring interfering with the
    lens mount.
    All the components in the D70 link to the lens via contacts connected to a
    chip in the lens. Some lenses can be converted to accept a chip and will
    meter in the camera. There's like one guy who does it, and he's very picky
    about which lenses he will convert.
     
    Sheldon, May 5, 2005
    #8
  9. Guest

    Guest Guest

    : > Are you sure it doesn't meter or just that it can't set aperture. I'd
    : > think you could put it in manual & see the +- slider thingy in the
    : > viewfinder.

    : It's not just that it can't SET the aperture, it also can't READ the
    : aperture. It has no way to know if you've stopped the lens down. The
    : camera has no mechanical coupling to the aperture ring, so turning the
    : ring sends no information to the camera.

    : Maybe they could have programmed it to support stop-down metering, or
    : maybe that would have confused people.

    That's what I'm thinking... it's what the Pentax does. Without knowing a few
    things about the lens (min/max aperture, current aperture), the more advanced features
    (auto-aperture, matrix metering, etc) cannot be done. That doesn't inherently mean
    that the meter should not function. The meter needs to see how much light is coming
    in the lens... that's all! Whether or not you set an aperture or have the body
    determine what aperture to use, the meter should still work.... at least wide-open
    metering (as you peer through the viewfinder).

    Now, it gets more complicated if you or the camera want to stop it down. I'm
    not familar with the mount... is there a physical lever that actuates the aperture
    from the camera, or is it *all* done electronically?

    I'm taking a look at this:
    http://www.mir.com.my/rb/photography/hardwares/nikonfmount/ais_lars.htm

    From that picture, the only important feature required for stop-down-metering
    would appear be the stop-down lever. If you set the ring on the lens to what you
    want, the camera moves the lever, takes a meter reading, and programs accordingly.
    What am I missing?


    *************************************************************************
    * Cory Papenfuss *
    * Electrical Engineering candidate Ph.D. graduate student *
    * Virginia Polytechnic Institute and State University *
    *************************************************************************
     
    Guest, May 5, 2005
    #9
  10. Guest

    Paul Furman Guest

    The D70 does have an manual button for DOF preview. Of course with an
    old lens that wouldn't do anything. It does seem fairly simple though to
    program a mode to meter actual light rather than calculating from wide
    open metering. This feature would enable all sorts of interesting
    arrangements. Even forget about auto metering shutter speed & just allow
    viewing the meter reading to shoot manual would be nice.
     
    Paul Furman, May 5, 2005
    #10
  11. Guest

    Guest Guest

    : The D70 does have an manual button for DOF preview. Of course with an
    : old lens that wouldn't do anything. It does seem fairly simple though to
    : program a mode to meter actual light rather than calculating from wide
    : open metering. This feature would enable all sorts of interesting
    : arrangements. Even forget about auto metering shutter speed & just allow
    : viewing the meter reading to shoot manual would be nice.

    Exactly... it's what the Pentax does on old lenses where it doesn't know what
    wide-open is. Hit a button to have it:
    - Stop down to what the aperture ring is set to
    - Set the shutter speed to the metered amount (via spot or center-weighted)
    - Release aperture, but hold setting as the current 'M' value

    The whole thing takes about 1/4 sec. I'm not clear from any
    pictures/descriptions of how the D70 mount works why that cannot be done.

    -Cory

    *************************************************************************
    * Cory Papenfuss *
    * Electrical Engineering candidate Ph.D. graduate student *
    * Virginia Polytechnic Institute and State University *
    *************************************************************************
     
    Guest, May 5, 2005
    #11
  12. Guest

    Paul Furman Guest


    For a manual aperture lens, I assume you would have a dark viewfinder?



    The lens has a little lever facing the mount, spring loaded to open up.
     
    Paul Furman, May 5, 2005
    #12
  13. Guest

    Guest Guest

    : > Exactly... it's what the Pentax does on old lenses where it doesn't know what
    : > wide-open is. Hit a button to have it:
    : > - Stop down to what the aperture ring is set to

    : For a manual aperture lens, I assume you would have a dark viewfinder?

    During the automatic stop/meter/set, yes the viewfinder is dark. Also, if
    you're using an even *older* (M42 screwmount) lens, the physical linkage does not
    actuate the aperture. Fortunately, those lenses have an A/M knob/ring/lever to
    manually stop them down. Then you can compose wide open, manually stop, have it
    meter, and fire. It's tedious, but at least it works.

    : > The whole thing takes about 1/4 sec. I'm not clear from any
    : > pictures/descriptions of how the D70 mount works why that cannot be done.

    : The lens has a little lever facing the mount, spring loaded to open up.

    Sounds like it works the same. Unless moving the ring on the aperture does
    not limit the *actual* motion of the iris when the camera body moves the lever, it
    should be possible to work the same way.

    -Cory

    *************************************************************************
    * Cory Papenfuss *
    * Electrical Engineering candidate Ph.D. graduate student *
    * Virginia Polytechnic Institute and State University *
    *************************************************************************
     
    Guest, May 5, 2005
    #13
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