Sharing lenses between N50 and D50?

Discussion in 'Digital SLR' started by Howard Larson, Jun 11, 2005.

  1. I have an N50 equipped with Sigma AF zoom lenses. I was thinking of
    moving into digital realm by buying a D50 body and sharing the Sigma
    lenses. Are there any pitfalls in this plan? Does the 1.5x factor
    mentioned in ads mean the effective focal length of the 35mm lens is
    1.5x greater?


    Howard Larson, Jun 11, 2005
    1. Advertisements

  2. Howard Larson

    DoN. Nichols Guest

    I have never handled these Sigma lenses, nor have I handled a
    N50, so I have to ask:

    "Is the lens fitted with a CPU (electrical contacts on the part
    which projects into the body)?"

    If it has the CPU, it should work with the D50 (and with the
    D70, which I do have and use).

    However -- if, for metering, it depends on the AI notches in the
    aperture ring, then it will probably only work in manual mode. You'll
    have to use a hand-held exposure meter with it -- or establish exposure
    via trial shots and "chimping" (looking at the resulting image on the
    display -- and at the histogram), and adjusting exposure appropriately.

    I know that my N90s uses either the CPU or the AI notches,
    depending on what a lens may offer. The D70 does not use the AI
    notches, other than one tab to tell the body that the lens is stopped
    all the way down.
    That is correct.

    DoN. Nichols, Jun 11, 2005
    1. Advertisements

  3. The 1.5x factor is bogus. The focal length does not change one millimeter.
    The only thing that changes is that the part of the image circle which forms
    the image on the sensor gets smaller, effectively giving you a cropped
    This means that the angle of view of a lens mounted on a D50 is smaller than
    that same lens on an N50, leading to the effect of making lenses with
    smaller focal length tele lenses.
    DOF, tele compression, etc. etc. don't change at all.

    To see the effect, take an image from your N50 and crop away about a third
    horizontally and vertically (while keeping the resulting image centered).
    That's what a D50 would produce with the same lens.

    As to whether your lenses will work:
    If they work on the N50 they should work on the D50.
    Jeroen Wenting, Jun 12, 2005
  4. Howard Larson

    DoN. Nichols Guest

    He said "effective" focal length --- which is shorthand for the
    coverage to be expected.
    Exactly what "effective" refers to. Most people use the focal
    length as shorthand for the coverage (angle of view), because they have
    lots of experience with what to expect on a full-frame 35mm camera with
    given focal lengths. DOF and other such features are usually secondary
    The DOF, when printed to the same size, should remain pretty
    constant. The smaller circle of confusion of the shorter focal length
    lens needed to give the same coverage will be enlarged with the image,
    giving the same effect.
    Precisely. Now -- enlarge that area to the same size print and
    you should get a better idea of what will happen.
    That one I was not sure of, since I don't know whether the N50
    depended on the CPU in the lenses. If it does, then the D50 should do
    the same.

    DoN. Nichols, Jun 12, 2005
  5. Well, there *is* no such thing as tele compression. It's where you're
    standing relative to the subjects that causes that effect. Neither
    the focal length nor the field of view affect the perspective.
    David Dyer-Bennet, Jun 12, 2005
  6. (DoN. Nichols), wrote in :

    Thanks, all, for the helpful answers.

    The N50 does have a set of seven contacts inside the body centered on
    the 12o'clock position. The Sigma lenses have a matching set of five
    contacts (two of the contact positions are not used).

    I have two zoom lenses on the N50: 28-80mm and 70-210mm. So, I
    assume these lenses, when mounted on the D50, would look like a
    42-120mm 105-315mm on a 35mm camera. Since the D50 comes with a
    Nikkor 18-50mm zoom, I thought I would buy it as well so as to have
    overlapping coverage of (in 35mm terms) 27-75mm , 42-120mm and
    105-315mm .

    I am assuming the Nikkor digital lens with 18-50mm focal length on
    the D50 would be equivalent to mounting a 27-75mm lens on a 35mm

    Am I interpreting this correctly or have I gone off into the weeds?


    Howard Larson
    Howard Larson, Jun 13, 2005
  7. Howard Larson

    DoN. Nichols Guest

    [ ... ]
    You're welcome.
    That sounds like a match for the three lenses which I have with
    a CPU fitted -- the "28-105mm f3.5-4.5 D", the "50mm f1.4", and the
    (converted to CPU) 180mm f2.8 manual focus. As viewed from the camera,
    I see one contact, two spaces, and four more contacts.
    Yes -- at least as far as coverage is concerned. The other
    focal-length related behavior (such as DOF) can lead you into endless
    debates on this newsgroup.
    This sounds right.
    And that 18mm wide end on the kit lens will give you the back
    what you lost to the crop factor from your 28-80mm lens. I don't know
    how much you use the wide angle end of your lenses, but you will have
    that back, and some extra telephoto reach.
    It sounds as though you have it all.

    I wonder how well the 18-50mm will work on your N50? I don't
    know whether it gives full coverage on a full frame. If it does, you
    will have also expanded your film capabilities.

    DoN. Nichols, Jun 13, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.