50mm "normal" lens with digital SLR?

Discussion in 'Digital Photography' started by john, Jun 19, 2004.

  1. john

    john Guest

    Hi folks,

    When I was in junior high photography class, we learned about how 50mm
    lenses were considered to be "normal" (ie. not wide-angle or telephoto).
    50mm was recommended for high quality shots where you could

    With my film SLRs, I always used my 50mm when zooming or wide-angle wasn't
    necessary, and I was very happy.

    Now that I've moved to digital SLR, the one lens that I have that isn't
    compatible with my digital camera is the 50mm lens (too old). I've found a
    good 50mm F1.8 for a very good price (less than $100). But the question I
    have is...

    With the digital magnification factor, a 50mm lens is pseudo-equivilent to a
    75mm. Soooo, is it still a "normal" lens anymore? Is there any real benefit
    to buying this lens?

    Thanks in advance!
    john, Jun 19, 2004
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  2. john

    Douglas Guest

    The 50mm lens is still one of the best lenses to have.It is a very nice
    portrait lens,and can be found at a good price!It is fast enough to get by
    without a flash,sometimes!The 50mm 1.8,as well as the 85mm 1.8 lens is,in my
    book,a must have!
    Douglas, Jun 19, 2004
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  3. john

    Phil Wheeler Guest

    On a 300D or 10D is will be 80 mm equivalent. I think you can buy a 50
    mm f/1.8 II for a Canon new for around $70. I have one and do not use
    it a lot. But it is a great lens for the price.

    I wouldn't call it a "normal" lens, but it is useful and a bargain.

    Phil Wheeler, Jun 19, 2004
  4. john

    ^ Guest

    I find an 80 mm (after 1.6 mulitplier) ideal as it corresponds to my
    personal "field of interest" - when I see something interesting enough
    to shoot, this lens crops it "just right" from where I'm standing (with
    some exceptions, of course :).
    ^, Jun 19, 2004
  5. john

    Frank Guest

    If you feel you'd like to have a good lens with a focal length
    equivalent to 75 mm on a 35 mm film camera it is worth while. Many
    people like the perspective of a 75 mm (or equivalent) lens for
    portraits. Actually, preferences for portrait lenses range from 75 to
    the old Nikon 105 mm jobs. I used to love my 105, but am happy with a
    somewhat shorter equivalent now.

    The lens that would give the visual effect of a "normal" lens on your
    DSLR is a 35 mm.
    Frank, Jun 19, 2004
  6. john

    Kakadu Guest

    The real new about the 1.6 magnification factor with DSLRs is that it is not
    actually a magnification factor at all. It is a *clip* factor. The lens
    resolves exactly the same as if it were on film except the area of the frame
    capture is smaller. Sort of like using 110 roll film in a 35mm camera.

    There are many side effects to this reduction of capture area. Probably the
    most usable is the fact that lens makers plagued with image fall-off at the
    corners can now sell their barely usable 35mm lenses as "made for digital"
    and achieve better results.

    Another side effect is the reduced capture size effectively clips the image
    so that a "normal" 50 mm lens will display the area of a 70mm telephoto lens
    but it will not be a telephoto picture, just one clipped down to capture a
    smaller area of the film/frame.

    A Photographers paradise.
    Kakadu, Jun 19, 2004
  7. john

    Phil Wheeler Guest

    And that is a very important thing, since lenses which might not work so
    well with a full 35 mm focal plane can be used effectively with the 1.6
    cropping of 300D, 10D or D70.

    Phil Wheeler, Jun 19, 2004
  8. john

    Tom Guest


    So far all the advice you have been given is flawed.

    The 50mm lens does NOT somehow magically become a 80mm lens when you stick
    it on a 1.6 crop factor camera. Neither is it a "pseudo-equivalent" as you
    state above.

    The reason portrait shooters like the short (80 to 105mm or so) teles is
    because the short tele has the effect of slightly flattening the image. It
    reduces the "Big Nose" syndrome where body parts (like the nose in a
    headshot) nearest the lens are exaggerated in size because of the
    perspective of the lens.

    A 50mm lens gives EXACTLY the same perspective on a 35mm camera, a
    medium-format 6x6, a 4x5 press camera, an 8x10 view camera or a digital SLR.

    The multiplication factor in digital SLRs is merely a crop factor, NOT a
    lens focal length transmutation device.

    Tom, Jun 19, 2004
  9. john

    Helge Olsen Guest

    THANK YOU! Finally a person who got the point! Kudos!

    Helge Olsen, Jun 19, 2004
  10. john

    Tony Spadaro Guest

    Tony Spadaro, Jun 19, 2004
  11. john

    Chris Brown Guest

    Every time this comes up, someone mentions this "perspective" nonsense.
    Perspective is simply the way distant objects appear smaller than nearby
    objects, and depends on where you stand. The focal length of the lens you're
    looking through has absolutely nothing to do with it - there's no way it
    can. If you stand somewhere and look at two identical balls, at different
    distances, such that the further ball appears to be half the size of the
    nearer one, it will still look half the size with no camera, when looking
    through a camera with a 28mm lens attached, when looking through a camera
    with a 35mm lens attached, when looking through a camera with a 50mm lens
    attached, ad nauseum.

    The reason people's noses look too big when their portraits are taken on
    35mm cameras with 50mm lenses is because in order to fill the frame, the
    photographer has to stand too close to the subject. You can try this for
    yourself with a willing volunteer, and no camera at all. Simply move your
    head closer and closer to their face, and notice how their nose starts to
    dominate the field of view as you get closer.

    When taking a portrait of someone with a 50mm lens on a DSLR with a 24mm
    sensor, you have to stand further back to fill the frame. In fact, you have
    to stand in the same place you'd stand were you using a 35mm camera with an
    80mm lens on. As a result, 50mm lenses make great portrait lenses on these

    Conversely, if you try taking a portrait of someone using a 6*6 medium
    format camera with an 80mm lens, and fill the frame, their nose will look
    bulbous, even though you're using an 80mm lens, because it has a wider angle
    of view on these cameras. By the same token, you can take someones portrait
    with a Coolpix 4500, and they won't look like they have a big nose, even
    though at maximum zoom, its lens only goes to 32mm.
    Chris Brown, Jun 19, 2004
  12. You mean like a 135mm lens is not a telephoto because if it were on a
    4x5 camera it would be a normal lens?

    You did make a very good point about the fact that lenses designed for
    full frame 35mm used on digitals with less than full frame sensor area are
    using the sweet spot of the lens so often the results are better than
    expected for a given lens. Many people miss this.

    A normal lens is usually described at the diagonal measurement of the
    image area. That works out to something less than 50mm, close to 47mm as I
    recall. Most digital sensors are smaller than 35mm film so they use the
    "factor" to adjust.

    As for the original question, I suggest that "normal" is whatever you
    want it to be. I don't like "normal" lenses. In 35 mm terms I like
    something a little longer like 75-80 and something wider like 24-35. But
    that is just what I like to work with. There is nothing magic about any of
    those numbers. Use what you like, not what I like or what is considered

    Good Luck
    Joseph Meehan, Jun 19, 2004
  13. john

    Frank Guest

    I wonder if all this is applicable. The real thing that affects the
    "perspective" in a photograph is the shooting distance, not the focal
    length of the lens. A 35 mm and a 150 mm lens, if shot from the same
    distance will display the same perpective (relative size of objects in
    the image.) They will not, however show the same image area. The real
    reason for using a short tele for portraits is to fill the frame for a
    head shot from a longer distance than you would use with a shorter
    lens, thus getting a more pleasing perspective. Thus it seems to me
    that a 50 mm (75 mm equivalent) when used at a distance to fill the
    frame with a head shot would be at the same distance as a 75 mm framed
    identically on a film camera and would see the same perpective.
    Frank, Jun 20, 2004
  14. john

    leo Guest

    I like using 50mm f/1.4 on Digital Rebel alot if there were no special
    requirement. Get the f/1.8 when your budget is tight. It's too cheap to pass
    leo, Jun 20, 2004
  15. john

    Nick C Guest

    Perhaps not.

    A lens may serve a duel purpose. It is what it is on a dSLR and on a SLR.
    The lens is not the determining factor in photo capture size, In a dSLR it's
    the size of the sensing element that's used. To say a picture is "cropped"
    because it's sensing element is smaller in size as compare to 35mm film is,
    IMO, wrong and misleading.

    To support my contention, one only need physically move from one position to
    another to obtain the same image prospective when using a given lens on a
    dSLR as opposed to a SLR. For example: A 50mm lens on a SLR has a diagonal
    view of about 46 degrees. The same lens placed on a 10D would be converted
    to 80mm having a diagonal view of about 30 degrees. To obtain the diagonal
    view of 46 degrees, one need only to physically move. It would be closer to
    the truth to refer to different image sizes obtained from a fixed photo
    position when using a dSLR as lens-sensor focal length multipliers. Reason
    being, the size of the sensor, in effect, 'resembles' using a given size
    teleconverter, without the loss of f-stops and using the best part of a
    lens, which is about 10mm from the lens center. If one were to accept the
    terminology that a given lens on a dSLR crops an image then one have to
    accept that all lenses, regardless of what type camera they may be used on,
    crops images because of changes in angles of view associated with different
    focal lenght lenses. Nope, I don't think it would be proper to accept that

    A lens which may perform poorly on a SLR may be a wonder on a dSLR that has
    a sensor (hopefully with large pixel sizes and thin boarders) which has a
    1.5x or 1.6x effect on a given lens. That's the way I see the differences,

    Nick C, Jun 20, 2004
  16. john

    Phil Wheeler Guest

    Only if it is one of those really heavy white ones :)

    Phil Wheeler, Jun 20, 2004
  17. john

    Nick C Guest


    I forgot to mention, Canon considers the sensor size in a dSLR as a lens
    multiplier and not a given lens as being an image cropper.

    In the spec section of the EOS 10D (for example), Canon clearly states:

    "Focal length conversion factor: Equivalent to approx. 1.6x indicated focal
    length compared to 35mm format." If Canon recognizes and refers to the
    sensor size (22.7 x15.1mm) as being a lens multiplier, why should I object.
    A 50mm lens on a 10D gives the same diametrical angle of view as an 80mm
    would give on a 35mm SLR. :)

    BTW, on the spec. sheet for the EOS-1D Mark II (which has my interest),
    Canon words it a little differently.

    "35mm-equivalent focal length is approx. 1.3 times the marked focal length."
    In my math book that means the 28.7x19.1 sensor has a 1.3 multiplying effect
    on a lens designed for the 35mm format being used on the Mark II. Kool.

    Sure makes one wonder if folks understand the meaning of "Focal length
    conversion factor." Not in any of Canon's literature that I have, which
    includes Canon's published book "EF Lens Work III, The Eyes of EOS" can one
    find where Canon refers to various 35mm lens effects upon a dSLR as
    "cropped" images.

    Nick C, Jun 20, 2004
  18. john

    leo Guest

    The whole thing about focal length is pointless unless it's reference to,
    let's say, 35mm frame. It's more acurate to state the angle of view. SO,
    it's a cropping fractor nevertheless. Try find a reasonable price ULTRA WIDE
    angle lens and you'd know the pain. I can simulate telephoto by cropping!
    What I mean is if they settle with 1.5x/1.6x crop factor, I'd rather use the
    4/3 format, at least the lens would be smaller & lighter.
    leo, Jun 20, 2004
  19. It _will_ be a telephoto picture.

    This is because the relative sizes of objects in the image is due to the
    relative distances from the camera. You get the "telephoto effect" by
    standing back from your subject (thus changing the relative distances
    between things in the image) and using either a longer lens or more
    magnification when printing.

    Basic reality check: A 110mm lens on my 645 camera takes images
    indistinguishable (other than resolution and DOF) from either a 75mm lens on
    a 35mm camera or a 16mm or so lens on a consumer digital. Short
    telephoto/portrait lens effect. Why would a dSLR somehow differ?

    What all this means is that if you take the same picture from the same place
    with a 75mm or 80mm lens on a 35mm camera, and a 50mm lens on a dSLR, and
    print them at the same size, there will be a _slight_ difference in depth of
    field (about the same as 1/2 and f stop), but otherwise the images will be

    So a 50mm lens on a 1.5x/1.6x dSLR is, exactly and only, a portrait/short
    telephoto lens.

    David J. Littleboy
    Tokyo, Japan
    David J. Littleboy, Jun 20, 2004
  20. john

    Phil Wheeler Guest

    Perhaps Canon, which does seem to try to simplify their manuals a bit,
    does not want to confuse their customers with the concept of "cropping
    factor". But in designing the EF-S mount, they clearly understand what
    is going on -- thankfully.

    Phil at dpreview


    likes the term "focal length multiplier".

    But a rose by any other name is a rose.

    So call it what you want.
    Phil Wheeler, Jun 20, 2004
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