Why do only primes have macro

Discussion in 'Digital SLR' started by Siddhartha Jain, Oct 7, 2005.

  1. Why is that macro capability exists only in prime (as in fixed focal
    length!!!) lenses? Other than primes, only a few cheap telephoto zoom
    lenses seem to have macro.

    In contrast, all P&S digicams have a macro feature and some like the
    Oly C-750 that I owned had a super macro too.

    - Siddhartha
     
    Siddhartha Jain, Oct 7, 2005
    #1
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  2. They do, look at the Canon 24-70L. I wouldn't call this lens cheap...


    ********************************************************

    "A nice man is a man of nasty ideas."

    _Introductions to History of the Reformation_
    Jonathan Swift
    1667-1745
     
    John A. Stovall, Oct 7, 2005
    #2
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  3. Siddhartha Jain

    salgud Guest

    There used to be a lot of telephoto zoom lenses with macro
    capabilities. A friend of mine had a Vivitar Series One 70-210 lens
    with macro capability. Don't know if they're still around, since I
    haven't been doing much photography for years.
     
    salgud, Oct 7, 2005
    #3
  4. Siddhartha Jain

    kctan Guest

    There is a diff between Macro and Close focus but people confused it. Macro
    in prime lens is true Macro i.e "flat field" whereas those Macro on cheap
    devices are actually "Close focus" and not "flat field". Flat field = centre
    to corners focuses are sharp without barrel or pincushion aberration.
     
    kctan, Oct 7, 2005
    #4
  5. That's funny my Minolta 35-70 and Tamron 28-200 both have macro settings -
    the former only at 70mm, but can get pretty close, the latter over the
    entire range, but not as close. OTOH my 50mm f1.4 does not have macro.
     
    R. Mark Clayton, Oct 7, 2005
    #5
  6. First, some terminology. Whatever the opinions of the "words mean
    whatever I want them to mean" school of thought, this is a highly
    technical area, and if you don't use the right terminology you will not
    find the answers in reputable sources.

    General photography uses magnifications of < 0.1.

    "Close up photography" is the term applied to the range of
    magnifications 0.1 to 1.0.

    "Photomacrography" is the term applied to the range of magnification
    from 1.0 to a rather ill-defined upper limit, usually about 50.0 (i.e.
    where the image is 50 times the size of the object). If you try to look
    up under the name "macrophotography" you will not find what you want in
    rigorous text books, as that means something else.

    There are mostly good reasons for this division; the equipment is
    generally different, and the simplifications of optics equations that
    work in one area break down (become inaccurate) in others.

    If a lens designed for normal photography is set in a mount which allows
    it to extend further from the position for normal photography - i.e. to
    focus a lot closer - then unpleasant things happen to the image.
    Spherical aberration (SA) rises sharply, contrast decreases, and
    astigmatism, coma and field curvature become obtrusive.

    To design lenses which work well in the m = 1.0 region and beyond,
    manufacturers have to use different design criteria. Different basic
    designs are often used, and may be used "back to front", i.e. the
    reverse way to that used in normal photography. Floating elements are
    often used to keep SA under control as the focus point moves, and to
    control field flatness. Steps also may need to be taken to control
    geometric distortion. Also, even after all these measures, it is
    necessary to limit apertures to f/2.8 or similar to keep SA within
    reasonable limits.

    With all this, you can see that it would be quite difficult to do this
    with a zoom lens, which already starts out with an often compromised
    design, lots of elements, and several complex cams to move the various
    bits around. So far as I am aware, there is no conventional zoom lens
    which is a true macro.

    You will see from the above that even most of the dedicated macro lenses
    for 35mm and related format DSLRs, used alone, barely qualify for the
    term macro. There is a whole world of specialised macro lenses for use
    in the range m = 1.0 to m = 50.0 which is rarely mentioned in these
    groups. These rarely have their own focussing movements, but are
    designed for use on bellows, adapted microscopes or dedicated stands. In
    truth it is not what the focus mount does which defines the lens, it is
    how well it works optically at the required magnification.

    (In case anyone raises it, the floating elements in many macro lenses
    with focussing mounts for 35mm cameras will often alter the focal length
    appreciably, so they might be thought of as a kind of zoom, or at least
    vari-focal lens. This however seems pure sophistry. Also, there exists
    among the true macro lenses for the region well above m = 1.0 at least
    one variable magnification lens, the Zeiss Luminar 2.5 - 5.0x. A zoom it
    is not, in any accepted sense at least.)

    Many manufacturers take close focus in their zoom designs to the point
    where quality starts to be compromised, and limit the action to this
    point. Others, rather dubiously, extend them to the point where they
    should know better, where quality is materially compromised, and then
    call them "macro". Frankly, they should be sued under trade description
    legislation.

    If you want to learn more about photomacrography, there are several good
    books and at least one discussion site on the subject.

    David
     
    David Littlewood, Oct 7, 2005
    #6
  7. Siddhartha Jain

    Norm Dresner Guest

    My Nikon 24-85mm "D" lens has a macro mode focusing to 1:2.

    Norm
     
    Norm Dresner, Oct 7, 2005
    #7
  8. Siddhartha Jain

    Bob Salomon Guest

    That's the point. one half life size is a close up not a macro ratio.

    Lifesize 1:1 or twice life size 2:1 are true macro ranges.

    A really good macro lens does not focus to infinity and probably
    requires a bellows to focus it. Most camera lenses that focus to
    infinity and then into what is marked "macro" or "micro" are simply
    lenses that focus rather close.

    Some examples of true macro lenses are Zeiss Luminars, Rodenstock Apo
    Rodagon D and Schneider M Componon lenses. All of these look either like
    microscope objectives (Luminars) or enlarging lenses (Apo Rodagon D and
    M Componon). None are any good at infinity and none will work as
    enlarging lenses.
     
    Bob Salomon, Oct 7, 2005
    #8
  9. They have what the manufacturer calls "macro" settings but those aren't
    macro at all, they're a sales pitch.
    Macro is 1:1 and larger, those lenses do 2:1 or worse at best.
     
    Jeroen Wenting, Oct 7, 2005
    #9
  10. Siddhartha Jain

    Annika1980 Guest

    A really good macro lens does not focus to infinity and probably requires a bellows to focus it.

    True that! When I got my 65mm MP-E Macro lens I thought I'd also be
    able to use it as a carry-around 65mm. Wrong.
    Maximum focusing distance is about 4" with this lens so the only
    landscape shots I've done with it are bug landscapes.

    http://www.pbase.com/bret/macro
     
    Annika1980, Oct 7, 2005
    #10
  11. Siddhartha Jain

    Jim Guest

    Because it takes a lot of engineering to get a lens that will focus that
    closely and still cover a 35mm image. The telephoto zoom lenses tend to go
    down to 1/4 size which is much easier to accomplish that the full size one
    gets with the fixed focal length lenses
    Because it is easier to accomplish.. By the way, do these lenses yield a
    full size image (that is, is the image on the sensor the same size as the
    object)? If it isn't full size, then you are comparing apples to oranges.
    Of course, this statement does not mean that such a feature is worthless. I
    have made many a photograph with a lens that will only go down to 1/4 size.
    Jim
     
    Jim, Oct 7, 2005
    #11
  12. Siddhartha Jain

    MitchAlsup Guest

    "regular" photographic lenses are designed to give their best focal
    performance (e.g. minmal spherical aberationm and other aberations
    "under control") close to the infinity focus position.

    "macro" lenses are designed to give their best focal performance close
    to the specified magnification -- that is a hand-full of inches.

    "telescopes are invariable designed for best performance at infinity,
    while microscopes are designed for best focal performance at a
    extremely close focal distances -- a handfull of mm.

    It is not well known, but lenses can only be designed for best
    performance at one set of coordiante distance pairs; where one
    coordinate is the front focal distance (entrance pupil to object) and
    the other is the back focal distance (exit pupil to image 'plane'). At
    any other combination of distances, spherical aberation is worse.
    No disagreement (as shown above).

    Mitch
     
    MitchAlsup, Oct 7, 2005
    #12
  13. Siddhartha Jain

    Bob Salomon Guest

    That is why some lenses have a floating element.
     
    Bob Salomon, Oct 7, 2005
    #13
  14. Indeed; which is why the very highest resolution lenses (microscope
    lenses, and those in chip fabrication) are designed to work at a fixed
    pair of conjugate distances.

    BTW, the "handful of mm" for microscope lenses goes down to about 0.1mm
    for high magnification varieties. Not a lot of working distance!

    David
     
    David Littlewood, Oct 7, 2005
    #14
  15. Siddhartha Jain

    Gormless Guest

    It should therefore be asked - why did you spend so much money on it without
    truly understanding it? It's hardly a cheap bargain lens.
     
    Gormless, Oct 7, 2005
    #15
  16. Siddhartha Jain

    Jer Guest

    Does every decision from others have to fit your particular profile of
    understanding to garner your acceptance? We don't really care if any of
    our decisions are acceptable to you, they need only be acceptable to us.
     
    Jer, Oct 7, 2005
    #16
  17. Which is why typical microscopes focus by keeping all the optical
    elements fixed and moving the subject into the focal plane.
    Not to mention oil immersion lenses.

    Of course, for imaging Small Things, the pesky wave nature of light
    eventually becomes sufficiently annoying, so we switch to electrons
    instead.

    -dms
     
    Daniel Silevitch, Oct 8, 2005
    #17
  18. Siddhartha Jain

    Mark² Guest

    Not so.
    My Canon 100mm 2.8 macro is one of the sharpest lenses available, and it
    focuses to infinity quite handily.
    True.
    Many lenses mark their closest focusing distance, but instead of saying
    "closest focusing distance: .4 meters", they say "Macro: .4 meters."

    -Always seemed rather unnecessarily confusing.
     
    Mark², Oct 8, 2005
    #18
  19. Siddhartha Jain

    Mark² Guest

    -Perhaps the sales person was a 16 year-old cutie, and Bret was too
    distracted to read the fine print??
     
    Mark², Oct 8, 2005
    #19
  20. Siddhartha Jain

    Mark² Guest

    -And it does 1:1...
    :)
     
    Mark², Oct 8, 2005
    #20
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