35mm equivalent sizes

Discussion in 'UK Photography' started by pp, Jun 11, 2008.

  1. pp

    pp Guest


    I have a 75 - 300mm telephoto that I bought for my Canon film camera. I have
    now gone digital and got a Canon 450D. If I use this lens on the 450D what
    would be the 35mm equivalent range? I can't remember how to work it out.
    pp, Jun 11, 2008
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  2. Geoff.
    Geoff. Hayward, Jun 11, 2008
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  3. pp

    Paul Giverin Guest

    As Geoff says, multiply by 1.6. So you are looking at 120-480mm.

    Paul Giverin

    British Jet Engine Website:- www.britjet.co.uk

    My photos:- www.pbase.com/vendee
    Paul Giverin, Jun 11, 2008
  4. pp

    pp Guest

    Thanks guys.

    pp, Jun 11, 2008
  5. pp

    Mike..... Guest

    Following up to Paul Giverin
    I just use 1.5 as its easier to work out :) A further point is that (I
    think) when using the rule of thumb with telephotos that you need a shutter
    speed at least the length of the lens, its the unmultiplied number thats
    relevant as the theoretical longer length of the lens is cropping not
    Mike....., Jun 26, 2008
  6. pp

    John Guest

    I am thinking a whole new language is needed to reflect the newer

    *Drop the 35mm equivalents and use 2x. 3x, -2x or something where a standard
    is defined as a certain angle of view. As CCD chip sizes vary I guess there
    can't be a single fact to give 35mm equivalent.

    *Stop using the expression "footage" when talking of video.

    *Come up with a noise that is different to an old SLR to give the impression
    (in drama) that a photo has been taken.

    *Is ASA/ISO film speed really relevant now? Again should we have something
    that is based on factors of a new norm?

    I am happy with the 35mm terminology - but feel it is meaningless to the
    younger generation.
    John, Jun 26, 2008
  7. pp

    Bruce Guest

    I think we should abandon terms like resolution, sharpness, contrast,
    plane of focus, depth of field, out-of-focus rendering, backlight,
    exposure value, focal length, shutter speed and aperture because they
    also seem to be meaningless to the younger generation.
    Bruce, Jun 26, 2008
  8. pp

    John Guest

    I am sure you made the comment 'tongue in cheek', but the ones you list are
    based on fact and are not numerically related to a single format that is no
    longer the main one in use.
    John, Jun 26, 2008
  9. pp

    Bruce Guest

    You aren't quite as daft as I thought.
    Bruce, Jun 26, 2008
  10. pp

    John Guest

    Perhaps angle of view of lens could be used - A telephoto would be
    (eg.10degrees: wide angle - 100degrees.) This would work - irrespective of
    the format size. Unfortunately a large telephoto would have a small number -
    so it may not appeal to the marketeers.

    What do you think Bruce and others?

    Could f numbers also be replaced - perhaps the old EV numbers were not such
    a bad idea if applied to digital. After all - does anyone need to know the
    effective diameter of the aperture as a ratio of the focal length?
    John, Jun 26, 2008
  11. pp

    John Guest

    I find it a bit amusing that 'anti-camera shake setting' on some budget
    cameras merely increases the sensitivity. A young friend of mine revealed
    this to me - when she wasn't satisfied with some photos taken in quite good
    conditions, I found that they had been taken at ISO 800.
    John, Jun 26, 2008
  12. pp

    Bruce Guest

    I was right the first time. You're *completely* daft. ;-)
    Bruce, Jun 26, 2008
  13. When I used to use medium format, I never felt the need to express focal
    lengths in 35mm terms!!

    You have a good point, why not (true) focal length / diagonal of sensor
    as a measure of 'zoominess'?

    Then for 35mm (which coincidentally has a 35mm diagonal of the sensor)
    we get:-

    28mm = 0.8z
    35mm = 1.0z
    50mm = 1.43z
    80mm = 2.29z
    400mm = 11.4z

    and you can do the same for your favourite format!
    F numbers are a non-dimensional variable which can be readily calculated
    - keep 'em & teach 'em. The real problem is that f numbers are actually
    expressed as 1/f.no. so people think that 11 is a 'large aperture' and 2
    is small!

    But since the sensor makers have crazily adopted a similar and less
    logical approach for a dimension (eg. 1/1.8"), it can't be that bad!


    [The reply-to address is valid for 30 days from this posting]
    Michael J Davis
    Some newsgroup contributors appear to have confused
    the meaning of "discussion" with "digression".
    Michael J Davis, Jun 26, 2008
  14. pp

    John Guest

    I like your point about not needing to think of 35mm equivalents when using
    medium format. I expect that sensors are in a number different sizes as well
    (although smaller) - so this adds weight to a non format way of expressing
    zoominess. (where Zoom vale 1 is equal to diagonal of sensor)
    John, Jun 26, 2008
  15. pp

    Trev Guest

    That is the problem the amount of sizes of sensors Its relatively easy with
    dslr's have mostly APS-c size then 4 thirds but when you get to the compacts
    that may be anything from 12mm to 4mm diagonals all claiming 35 to 140
    Trev, Jun 26, 2008
  16. pp

    Rob Morley Guest

    Except the image size in a full-frame 35mm film camera is 24mm x 36mm,
    so the diagonal is about 43mm.
    Rob Morley, Jun 27, 2008
  17. Whoops! You are right!! That's even better - was expecting the 50mm
    factor to be nearer 1!

    Sorry for the confusion. The principle is OK though!


    [The reply-to address is valid for 30 days from this posting]
    Michael J Davis
    Some newsgroup contributors appear to have confused
    the meaning of "discussion" with "digression".
    Michael J Davis, Jun 27, 2008
  18. pp

    savvo Guest

    Let's not have facts get in the way of an important, innovative idea.
    savvo, Jun 27, 2008
  19. pp

    Rob Morley Guest

    The concept of wide/normal/long lenses has long been linked to the
    image diagonal, but people tended to think of the ratios in terms
    of focal lengths for 35mm (normal ~ 50mm) and 6x6 (normal ~ 80mm)
    because those were the prevalent formats. Formats are so varied these
    days that a more general system makes sense. You can be sure that
    users of large-format cameras, arguably some of the most 'serious'
    photographers, don't think in terms of 35mm equivalents.
    Rob Morley, Jun 27, 2008
  20. pp

    John Guest

    Whilst the focal length and its relationship to the diagonal (diameter of
    image cast by the lens) is the principle - the image size was more
    appreciated when one worked with slides, plates, negatives. In most digital
    cameras (incl video) the sensor is never seen and the user is not conscious
    of it.

    Again - any thoughts on expressing the angle of view as a way of describing
    a lens in advertising and specifications - rather than constantly referring
    back to 35mm?

    In case Bruce thinks I am a young upstart - then I will admit to my first
    camera being a folding Kodak which took 620 film (3.5 x 2.5" if I recall
    correctly. I used to load the film from bulk in my darkroom by sticking it
    onto reclaimed backing papers. The f/6.3 lens seems big. Before moving to
    digital I used a Ziess Werra and then several SLRs (Canon and Olympus).
    Thanks for showing how to debate a point Bruce.
    John, Jun 27, 2008
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