Definition of DSLR

Discussion in 'Digital SLR' started by RichA, May 15, 2005.

  1. RichA

    RichA Guest

    A single lens reflex used to be considered
    a camera with a viewfinder that imaged through
    the lens. But nearly all digital cameras do this,
    albeit using an electronic screen for the image.
    So would the term, DSLR now have to include
    a viewfinder that allows the eye to see the
    lens image directly? Does it also mean
    the camera must have removable lenses?
    RichA, May 15, 2005
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  2. RichA

    Alan Browne Guest

    This was all debated, unsatisfactorilly to some, during the forming of
    this ng and the .zlr ng.

    Please let sleeping dogs lie.

    Alan Browne, May 15, 2005
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  3. The key word is "reflex", implying the use of a mirror. Only what are
    considered SLRs (or the now-discontinued ZLRs from Olympus) use mirrors to
    provide the TTL viewfinder image.

    Martin Francis, May 15, 2005
  4. RichA

    MarkH Guest

    To be similar to over 99% of SLR camera it would need to have
    interchangeable lenses. A camera that is technically a D-SLR, but with a
    fixed lens has little relevance to this group, since it is an oddball and
    different in important ways to all other cameras discussed here.

    The only D-SLRs I know of that don't have interchangeable lenses are the
    Olympus E-10 and the Olympus E-20. But the newer of the 2 was released 3.5
    years ago and Olympus have not continued that line, they have instead
    released interchangeable lens D-SLRs.
    MarkH, May 15, 2005
  5. RichA

    G.T. Guest

    What does zlr mean, anyway?

    G.T., May 16, 2005
  6. RichA

    birdman Guest

    If the EVF is improved to the point where it is actually usable, and
    lens/sensor aberrations are automatically corrected by software, and the
    lens has a reasonable zoom range, will the comparitively ancient
    interchangeable SLR form factor (dating back to the 1930s: 3/4 of a century)
    birdman, May 16, 2005
  7. Sleeping dogs don't hardly talk... How come you think they lie?
    Steve Cutchen, May 16, 2005
  8. RichA

    Frank ess Guest

    They're always telling you they are chasing a rabbit, and you can see
    it ain't so.
    Frank ess, May 16, 2005
  9. G.T. wrote:
    Zoom Lens Reflex - often used to describe the higher-end point-and-shoot
    cameras which resemble SLRs in shape and handling but do not have a full
    interchangeable lens capability. The reflex is electronic rather than by

    David J Taylor, May 16, 2005
  10. RichA

    Frederick Guest

    No it won't.
    When the EVF provides great resolution with high refresh rates and no
    lag, then the mirror can go. Interchangeable lens bodies will stay.
    The SLR form factor isn't decided by limitations imposed by reflex
    mirrors/prism. It would be easy to make a impractically small DSLR
    loaded with features. If you want instant access to functions, then you
    need lots of buttons and dials. These need to be in a place where your
    fingers can get at them easily. That's why many zlrs use an slr like
    design, even if many are to small for my fingers. It's also why pro
    cameras are usually quite big.
    Frederick, May 16, 2005
  11. RichA

    Alan Browne Guest

    It's a term coined by one of the vendors (Pentax IIRC) to describe the
    more advanced all-in-one camera. Typical examples include the Minolta
    A1/A2, Sony 727,828 and many others. Usualy characteristics: full set
    of photographic controls (ISO, S, A, exp comp, etc. etc.), a very good
    to excellent quality zoom lens covering a focal length of about 28mm to
    200mm (in 35mm equivalent) and a 35mm type flash shoe. Some have a
    reflex mirror, some have two monitors (back and viewfinder). Usually
    have fairly small sensors.

    The main non-SLR characteristic is the absence of interchangeable
    lenses. This was one reason why this NG ended up being called
    ..slr-systems instead of .slr

    In the end this group (which was the sole original proposal) is

    Of the "tack onto the proposal" groups (zlr, point+shoot and
    rangefinder), only zlr has managed to be very modestly successful. P+S
    is a few posts a day, rangefinder is a few posts per month.

    Alan Browne, May 16, 2005
  12. RichA

    G.T. Guest

    Thanks Alan. BTW, how many digital rangefinders are available?

    G.T., May 16, 2005
  13. RichA

    Alan Browne Guest

    I really don't follow it. There is a very nice Leica M-mount Epson
    which I believe uses the same sensor as the 7D, D100/D70, *istD.
    (No review, just the facts, I've never heard of anyone owning one).

    I don't know of any others.

    Alan Browne, May 16, 2005
  14. It's on my possible's list but the problem I see is the rangerfinder
    base is short. I would have hope they would have used the long base
    found in the M body Leicas.


    "Man came silently into the world."

    Pierre Teilhard de Chardin
    _The Phenomenon Of Man_
    John A. Stovall, May 17, 2005
  15. RichA

    Alan Browne Guest

    What do you mean by "long base"?

    I assume you mean some leverage or magnification effect in the
    viewfinder optics? (I seem to recall that Leica M6's have different
    magnification in the VF).

    If that is the case, then it would be odd that the Epson doesn't offer
    similar options, esp. considering the price.

    Alan Browne, May 17, 2005
  16. RichA

    DoN. Nichols Guest

    The "long base" is short for "long baseline" -- that is the
    separation between the two forward-looking optics of the rangefinder.
    The greater that baseline, the more sensitive the rangefinder mechanism
    is, and thus the easier to use.

    Most binoculars increase your baseline, so you get better depth
    perception. Note that the Objective lenses are more widely spaced than
    the eyepieces, which are (of course) constrained by the spacing of your

    Even if you simply set up a pair of simple periscopes, rigidly
    mounted to a common frame, so the points from which you are looking are
    more widely separated, you will find your ability to judge distance

    The mechanics of a long baseline require a bit more work in the
    design of the camera body. Magnification is easy to add, separating the
    objective ends of the rangefinder in an existing body design may be more
    difficult -- depending on what else is in the way. (In film cameras,
    things like the rewind knob and spindle, and a top-mounted film advance
    lever may contribute to the list of obstructions.

    DoN. Nichols, May 17, 2005
  17. RichA

    Alan Browne Guest

    Ah, makes sense.

    Alan Browne, May 17, 2005
  18. RichA

    RichA Guest

    There has to be a point at which increasing the baseline no longer
    benefits the ability to focus, given average human eyesight.
    But I remember military binoculars that could have their objective
    lenses separated by up to 2 feet.
    RichA, May 17, 2005
  19. RichA

    Alan Browne Guest

    Range finders for artillery had to be accurate well beyond the
    hyperfocal of the lens to determine distance accurately (at least that's
    what I assume you're referring to). So a stereo rangefinding solution
    with a wide baseline is desirable.

    For a rangefinder camera, if my assumptions are correct, it would only
    need rangefinding accuracy up to a little beyond the hyperfocal distance
    for the largest aperture of the longest lens in the collection for the
    camera. The longest lens I can find for Leica M is 180mm f/2.8 so that
    comes to a little over 460 meters (for 0.025 CoC).

    It may all 'wash' out in the design of the focus coupling to the lens, I
    really have no idea.

    Alan Browne, May 17, 2005
  20. RichA

    RichA Guest

    What is the benefit of a rangefinder? In the days of film only,
    they offered a pretty silent means of getting pictures, no mirror
    and soft shutters.
    RichA, May 18, 2005
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