Canon 50mm f1.8???

Discussion in 'Canon' started by jazu, Dec 14, 2007.

  1. jazu

    philippe Guest


    If they can't take a joke.... :)
    philippe, Dec 15, 2007
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  2. jazu

    philippe Guest

    That's just cool :D
    philippe, Dec 15, 2007
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  3. jazu

    Ali Guest

    I was referring to 24mm on a 1.6 cropped sensor body, which is the approx.
    equiv. as a 35mm lens on a full frame/35mm film body. For me, I love 85mm
    and 35mm (35mm equivalent FOV) focal lengths. Although, it's not really
    important, a camera is only a tool at the end of the day, and of course
    everyone has their own preferences. There's no real right or wrong. I have
    seen very good landscape shots taken with telephoto lenses, but then you
    normally have a bit more room.
    Ali, Dec 15, 2007
  4. jazu

    Ali Guest

    Ah, don't be confused between exposure bracketing and the 'aperture
    bracketing' that I was referring to. This is not an exposure issue, it's a
    DOF issue. FWIW, I agree with you about exposure and for me correct
    exposure is still as important now as it was with film and slides.

    I would like to bracket for DOF. Just an example, in AV mode, shoot at
    f/2.8, but bracket f/2 and f/4. Or even bracket for f/1.4 and f/5.6.
    Giving the fast fps available, 3 shots could be reeled off pretty quickly
    (if there is sufficient light of course) and it is nothing more that a
    software change. The hardware remains the same.
    Ali, Dec 15, 2007
  5. jazu

    Paul J Gans Guest

    Paul J Gans, Dec 16, 2007
  6. jazu

    Robert Coe Guest

    : In article <>, Ali
    : > The focal length is great for single person shots on a 1.6 cropped sensor.
    : > For group shots, a 24mm would be a better solution, although you need to
    : > be careful using a big aperture to get the shutter speed, as the DOF could
    : > mean that some of the people will be out of focus. This is where aperture
    : > bracketing would be useful (hint, hint Canon)!
    : Whenever possible, I always used a longer lens for groups (back in film
    : days).
    : As for bracketing...a technique for losers.

    Calling those who embrace risk-avoidance techniques losers is one of the
    simple pleasures of a shithead.

    Robert Coe, Dec 16, 2007
  7. jazu

    philippe Guest

    Actually, he expanded on that and cleared up what he meant by it.

    Whether you agree with it or not is irrelevant to the fact that you are
    either knee-jerking or attacking out of fun.

    Or you don't read threads..
    philippe, Dec 16, 2007
  8. Yes, definitely, especially on a digital SLR with 1.6x lens factor.

    It's great for indoor use purely because of that large f/1.8 aperture which
    allows shooting in natural light. But for a group around a table as you
    describe, it would be a poor choice on a full-frame and practically useless
    on an APS-frame camera.

    Neil Harrington, Dec 16, 2007
  9. <guffaw!>

    That's putting it succinctly.

    Neil Harrington, Dec 16, 2007
  10. You got a very basic flaw in your line of thinking: indoor use does not
    equal group of people around a table.

    Yes, a 50mm f/1.8 is a great lens for indoor use.
    No, a 50mm is usually not a good lens for shooting a group of people around
    a table, no matter if that table is indoors or outdoors.

    Jürgen Exner, Dec 16, 2007
  11. jazu

    Mr. Strat Guest

    If you learn how to properly create an image, you won't need to resort
    to crutches.
    Mr. Strat, Dec 16, 2007
  12. jazu

    Mr. Strat Guest

    Why not take it right in the first place?
    Mr. Strat, Dec 16, 2007
  13. No, it does not. It still is a 50mm lens in all respects,
    like DOF[1].

    The FOV, however, is similar to a 80mm lens on a 35mm film
    (24mmx36mm sensor) camera --- but that is a property of the
    camera snipping away the borders, not a property of the lens,
    as taking the very same shot with a full frame sensor/film and
    trimming away the borders will prove.
    Though the f/1.4 is much nicer to use, hold, touch, (and has a
    better bokeh!), alas, it is much dearer.


    [1] Which is why these 8 or 12mm lenses that provide the same
    FOV as a 50mm on a 35mm camera have such extreme DOF ---
    they are very very short lenses, and not 50mm lenses.
    Wolfgang Weisselberg, Dec 16, 2007
  14. jazu

    Paul Furman Guest

    On a smaller sensor there is more DOF. I believe the way it works out is
    less DOF though: the DOF increases but to frame the same subject you
    have to step back and that makes the DOF shallower. Maybe it's a wash...
    depending on the distance involved... maybe the only difference is you
    have to step back further. The exposure time remains.
    Paul Furman, Dec 17, 2007
  15. Go shoot a film with a 50mm lens. Then cut out the centre of
    the image. Does the mere act of cutting change DOF? No!

    Hence: Same focal length, same aperture => same DOF, no
    matter the crop factor.

    What you are thinking about is keeping the FOV (field of
    view) identical, but changing both the sensor size and the
    focal length. You are comparing a 50mm at full frame with a
    31mm at 1.6x crop with a 10mm at 5x crop at the same

    I compare a 50mm on full frame with a 50mm on 1.6x crop (FOV:
    80mm on full frame) with a 50mm on 5x crop (FOV: 250mm on full
    frame) at the same aperture.

    Wolfgang Weisselberg, Dec 17, 2007
  16. jazu

    acl Guest

    If you are talking about DOF on a print of a given size, then yes: the
    image from the smaller sensor will have to be enlarged more. Now if
    you don't like this definition of DOF that's fine with me, but that's
    what is used everywhere (eg in the wikipedia article that you quoted
    last time you said this-by the way, you ignored my pointing out this
    mistake last time).

    look at the eqns for DOF: they include a circle of confusion. That'll
    change with format.
    acl, Dec 17, 2007
  17. jazu

    Ali Guest

    I'm, with Paul on this one. Because before you cut the centre out of the
    image, you would need to take a few steps back from the subject before
    shooting the photo, so that once you cut the centre out of the image, the
    image is the same FOV. Because you have taken a few steps back from the
    subject to get the same FOV, you have just increased the DOF. Agreed, it
    can be a bit of a head f*ck. ;-)
    Ali, Dec 17, 2007
  18. I guess you summarized it quite nicely and apparently it comes down to a
    disagreement on what are the "comparable conditions" for evaluating DOF:
    same distance between object and lens or same FOV.
    It is the same difference as between the actual focal length of a lens or
    the apparent/35mm-equivalent focal length of a lens. The former is
    technically correct and the latter is actually used by people.

    I agree with Wolfgang. Comparisons should be done with changing just one
    parameter. That means when comparing the DOF of a specific lens on a
    full-frame and a DX camera, then I change that camera body to test the
    different sensor size. But I keep all other parameters the same, in
    particular the position of the camera.

    Jürgen Exner, Dec 17, 2007
  19. jazu

    Paul Furman Guest

    I messed it up some. More DOF on a small sensor only if you use a
    shorter focal length to achieve the same FOV, less apparent DOF if you
    step back to frame the same subject. So if you like fast telephoto, the
    crop is a boon, if you like fast wide angle it stinks.
    Paul Furman, Dec 17, 2007
  20. jazu

    Paul J Gans Guest

    I don't think so. First, depth of field is a subjective
    measure of sharpness. As you enlarge a picture (including
    film) the apparent sharpness decreases.

    Now what you say above is almost reasonable. But we have to
    compare the apples with apples and not oranges. Shoot a picture
    with a digital camera using the 50mm lens. Print the picture as
    a 4x6. Now you shoot film of the same subject with the same 50mm
    lens and the same aperture setting. Trim the negative to get rid of
    about 37% of the outer part. This corresponds to the 1.6 "crop" factor.
    NOW print that as 4x6.

    It is this last part of blowing the negative up that decreases the
    depth of field.

    If my brain was working better today I'd calculate it all out for the
    same circle of confusion *on the final print*. But my guess, based
    partly on experience, is that the sharpness of the 50mm is decreased
    somewhat when used on a 1.6 crop factor digital.
    Paul J Gans, Dec 17, 2007
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