Digital/35mm focal length question

Discussion in 'Photography' started by Gordon, Jul 3, 2007.

  1. Gordon

    Gordon Guest

    I see conversions from digital focal length to 35mm focal length in EXIF
    data on folks photo galleries, i.e. 800mm (35mm equivalent=1200mm). Is
    this conversion on any kind of curve or is it a constant?

    Gordon, Jul 3, 2007
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  2. Neither nor. It depends on the camera you are using or more precisely on the
    physical size of the sensor in that camera.

    Jürgen Exner, Jul 3, 2007
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  3. Gordon

    Kadin2048 Guest

    Just to followup on Jue's answer, the conversion is a constant, given a
    certain-size sensor, but it differs between sensors.

    E.g., APS-size sensors will have a "35mm equivalent" equal to
    approximately 1.25 times the APS focal length. (A 100mm lens on an APS
    sensor would give about the same results as a 125mm lens on a 35mm
    sensor / film pane.) However, a small P&S sensor would have a different
    conversion factor.

    There are many charts available online; the conversions become important
    not only with digitals but also when choosing lenses for medium- and
    large-format systems.

    Kadin2048, Jul 3, 2007
  4. It only applies to the inferior APS-C cameras, not the full-frame cameras.

    David J. Littleboy

    Tokyo, Japan
    David J. Littleboy, Jul 4, 2007
  5. Gordon

    acl Guest

    Come now, the Australian Public Service Commission has nothing to do
    with this.
    acl, Jul 4, 2007
  6. Gordon

    frederick Guest

    It doesn't *only* apply to APS-c. Some large format slrs have crop
    factors, unlike inferior 35mm sensor size slrs.
    frederick, Jul 4, 2007
  7. Gordon

    ray Guest

    That is a constant factor which can be different for different cameras. It
    depends on the size of the sensor in the camera, and there are quite a few
    different sensor sizes.
    ray, Jul 4, 2007
  8. Gordon

    Bob Williams Guest

    The conversion factor is equal to the ratio of the diagonal of 35 mm
    film (43.3mm) to the diagonal of the sensor in the camera of interest(x
    mm). Factor = 43.3 / x.
    Bob Williams
    Bob Williams, Jul 4, 2007
  9. Gordon

    Koekje Guest

    ["Followup-To:" header set to]
    David J. Littleboy enlightened us with:
    It also applies to the superior APS-C cameras and the mediocre APS-C

    Koekje, Jul 4, 2007
  10. And to the bottom-of-the line P&Ss<_>
    Tzortzakakis Dimitrios, Jul 4, 2007
  11. Gordon

    smb Guest

    There are no inferior formats, there are only inferior photographers.

    "Full Frame" is a misconception. The 35mm format itself is an
    "inferior" format, which was originally an adaptation of movie film to
    still cameras. Good photographers took hold of that format and made
    it the standard it is today.

    The same is true of the various APS formats. Digital is not film,
    so there is no reason to think that "full-frame" digital is superior
    to other formats developed for digital. There are ups and downs to
    each. The only thing that matters is what you do with the format you

    Full-frame digital is superior for making very large prints, but it
    comes with its own disadvantages. Medium format film is also
    superior to 35mm film for making very large prints; but fewer
    photographers use it for similar reasons to why fewer photographers
    use full-frame digital.

    But you know all this, David. You just like to put down anything that
    is not a full-frame Canon. But sensor size is not the whole picture.
    For example, the Canon 5D may have the better sensor in terms
    resolution and noise reduction, but the Nikon D200 beats the 5D in
    every other measurement, and it comes at a much lower price point. At
    the print sizes that most of us make, the D200 can actually make more
    pleasing images.

    So why even fool around with an inferior full-frame system from an
    office equipment company when you should be using the superior digital
    medium format from *real* camera companies like Hassleblad, Pentax or

    smb, Jul 15, 2007
  12. Gordon

    Noons Guest


    And in 3-4 years time when most camera makers will
    have ff sensor cameras out and will start dropping 1.6 and
    1.5 formats, I want to see the arguments from those who
    will jump in now, vociferating against you that APS-C is
    not an inferior format!

    Me? I'm on my second 6x7 film camera! ;-)
    And the F4 and zeiss r/f continue to trod along famously.
    Almost fell into a well-priced D200, but resisted
    at the last moment!
    Noons, Jul 15, 2007
  13. Gordon

    frederick Guest

    That's interesting!
    Will companies like Pentax drop APS-c _and_ 35mm format digital in
    favour of their 645 digital format?
    6x7 film cameras suck for many things.
    35mm film sucks for most.
    frederick, Jul 15, 2007
  14. Gordon

    smb Guest

    Me, I'm still on my first 6x7 film camera. Wonderful negatives and
    nice big prints can come from it. However, I rarely use it anymore
    since my D200 will run circles around it in just about every shooting
    situation. Point being, ultimate resolution and print size don't
    mean much if you can't get the shot to begin with. :)

    I would like to blow the dust of the 6x7 again for some nice static
    landscapes and such, I'll bet those negatives scan into some nice big
    digital files.

    smb, Jul 15, 2007
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