Optical Quality: AF vs MF

Discussion in '35mm Cameras' started by Mike - EMAIL IGNORED, Aug 28, 2004.

  1. Generally speaking which category has better optics:
    Auto-Focus or Manual Focus?
    Mike - EMAIL IGNORED, Aug 28, 2004
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  2. In 35mm camera lenses, neither is a reliable indication of quality,
    and junk comes in both types.
    David Dyer-Bennet, Aug 28, 2004
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    bmoag Guest

    The difference is not in the lens optics it is in the focusing/viewing
    screen. In most autofocus cameras the viewing screen is very difficult to
    use for critical manual focusing.
    bmoag, Aug 28, 2004
  4. IMO, manual focus lenses give you the best quality for the money, simply
    because they have been made for many years, and the used market is flooded
    with them. Bear in mind however, that optical design has improved over the
    years, and the newest glass is probably the best, although it will also be
    the most expensive. But the real bargains are in the pre-AF lenses that are
    ten years old or older.....
    William Graham, Aug 28, 2004

    Tony Spadaro Guest

    Tony Spadaro, Aug 28, 2004

    Bandicoot Guest

    Good and bad examples of both abound - you can certainly get first rate
    optics in either.

    However, AF is not as accurate as _careful_ manual focus, so manually
    focussing will give you better results, other things being equal (ie., we
    aren't talking about you shooting a subject that is fast moving and really
    benefits from AF, and you don't have fading eyesight.)

    The issue then is that _some_ AF lenses are harder to focus precisely
    manually than MF ones, just because of the 'looser' focus mechanism that is
    designed to reduce the load on the AF focus motor. There are also lots of
    better AF lenses where this isn't the case, notably those with a focus
    clutch or similar mechanism - though this isn't a requirment for good MF
    feel, as the Pentax FA-Limited lenses show.

    The focusing screens in AF bodies also don't help. They are designed
    assuming that focusing isn't their prime job, and so are optimised for
    brightness and 'smoothness' which can make precise manual focus (and
    especially fast and precise manual focus) harder to achieve.

    So the best lens optics exist in both. The best results from those optics
    are usually from manual focus or 'top end' AF lenses on manual focus
    bodies - or AF bodies with their focusing screens replaced with ones more
    suited to the task of focusing.

    All the same, if your body has a good AF system, the differences in final
    sharpness will often be less than the difference that is made by using a
    tripod - ie., this is the way to get 'the best' results, but you'll see a
    bigger differnece by using good technique first, and only then looking to
    squeeze out the last ounce of performance.

    Bandicoot, Aug 28, 2004

    PGG_ Guest

    PGG_, Aug 28, 2004

    greg Guest

    Geez, what a quickly thrown-together document! ;-)
    greg, Aug 28, 2004

    Alan Browne Guest

    For the lens, the only difference is the drive to move the focus,
    the optics otherwise can be the same.

    The focusing screens in AF cameras make critical manual focusing
    more difficult than with a MF system... this does not reflect on
    the lens quality.

    Final point, AF systems cannot focus as accurately as the human
    eye can focus (with a MF viewfinder), so with AF there is a
    certain probability that the focus is a tad off from 'best'.
    Selecting higher DOF helps alleviate this where possible...

    Alan Browne, Aug 28, 2004
  10. Mike - EMAIL IGNORED

    Tony Spadaro Guest

    Monagan is anti AF and tends to load his "facts" to benefit his opinion. He
    also thinks Vivitar and Phoenix lenses are as good as Canon and Nikon -
    which leads one to wonder --- does it matter whether one uses MF, AF or NoF.
    If you are dumb enough to believe the crap on his site -- it does not bother
    me -- I'm not the one basing expensive decisions on crap, so I have no
    concern at all. Goodbye, troll.
    Tony Spadaro, Aug 29, 2004
  11. Mike - EMAIL IGNORED

    Colin D Guest

    Well, I read some of it - the author seems to have a bad case of verbal
    diarrhoea - the article is HUGE. But huge doesn't mean correct. And
    it's largely the opinion of one man. Further, the article was written
    more than four years ago, using cameras extant at the time. The last
    four years haven't been wasted as far as camera development goes, so he
    is plain out of date.

    I can pick holes in his approach and conclusions in numbers of
    instances. He carries on about AF 'focusing on an eye and getting the
    chin', and other critical focus situations - but these are usually
    portrait or even studio shots, where AF is inappropriate. Nobody who
    knows what they are doing would use AF in that scenario.

    He prattles on about sensors that are only able to resolve about 25
    lpmm, let alone 50 lpmm. Here's something you might like to think
    about. Since the screen in an slr is the same size as the film frame,
    greater than 50 lines per mm on the film is also greater than 50 lpmm on
    the viewing screen. Given that the viewfinder optics provide some
    magnification, you are asking the screen to be able to show such fine
    detail, and your eye to resolve it. I think the truth is that one
    *can't* see such detail, and the act of focusing consists of adjusting
    the focus both ways until one *can* see the image is just out-of-focus,
    then guessing the midway position where hopefully it will be sharp.

    Conversely, he totally ignores the situations where AF is useful -
    'grab' shots, sports, fast-moving subjects, even ordinary general
    photography where, because there is no absolute pinpoint that *needs* to
    be in focus (a group shot - whose eye are you going to focus on?). And,
    many modern AF cameras, certainly my Canons, have a 'dep' setting, where
    the camera figures out the required depth of field and sets the
    resulting aperture and focus point, far faster than any human could do
    it. Not used often, but it's there if you want it.

    Lastly, a very valid point that has been made many times, and I make no
    excuses for making it again. Manual focus, especially on 35mm cameras,
    is good only *IF* the user has very good eyesight. There are many
    camera users, like me, who are not 21 anymore, and whose sight is simply
    not good enough to focus the damned camera manually. It's also slower -
    there aren't many who can snap the image into focus without some racking
    back and forth to ascertain the focal point. Remember seeing those MF
    users screwing the focus ring backwards and forwards a dozen times
    before taking the shot? Then, a moment later, because someone moved,
    doing it all again? Subjects calling out 'Hurry up, take the shot'?

    In such - and indeed nearly all - situations, AF works better. It might
    not be perfect, but it's better. A good analogy is the auto box in your
    car. Sometimes it doesn't do what you want, and you select manual
    second, or whatever. But do you say 'I hate my gearbox. I'm gonna get
    a stick shift'? No, you learn to use the auto properly, and so it is
    with AF cameras.

    Colin D.

    Beware the Pontificators. They are rarely Performers.
    Colin D, Aug 29, 2004
  12. Mike - EMAIL IGNORED

    PGG_ Guest

    You mean that the Nikon F5, the Minolta Maxxum 9, and the Canon EOS1v
    cameras are out of date?

    What about the discussion on focusing screens? Or how AF lenses are
    AF is absolutely useful for sports, wildlife, and other
    fast-moving subjects. For everything else, it is not useful and possibly
    even detrimental.
    Valid point.
    You are talking to the wrong guy here. My 2000 Maxima has a 5-speed
    manual transmission. I love it. Even my 60-year old mother drives a
    manual in her Mazda Miata. I guess it runs in the blood.

    AF is great for most people. The article I posted may be biased, but
    I think there is some merit in it.
    PGG_, Aug 29, 2004
  13. Mike - EMAIL IGNORED

    PGG Guest

    He may be biased, but I don't think you can dismiss his data so quickly.
    In fact he has data and you don't. So am I dumb or are you just an old,
    ignorant man?
    PGG, Aug 29, 2004
  14. Mike - EMAIL IGNORED

    columbotrek Guest

    When percise focus matters (micro and portrait work comes to mind) I
    always use MF. If you are using a AF screen, it is hard to tell exactly
    where the focus point is. But by setting the focus half way between
    when you detect out of focus at the near and far, you can get really
    good results. With a MF screen, the split really helps if the image is
    bright enough. As far as the design goes. The older MF lenses were
    marketed towards the professional and so most all were good. There was
    no consumer grade then. If you wanted cheep you did not buy from the big
    5 (Nikon, Canon, Minolta, Pentax or Olympus) New glass clearly is
    divided into pro and consumer grade and most or all are AF. There are
    some really excellent lens designs now which were not possiable to make
    20 years ago. Or even 2. Especially in the Zoom lenses. And there are
    some, shall I say, compromised designs. You just have to do some
    research to figure out what is what and what is important to you.
    However the old axiom of you get what you pay for helps. Don't expect a
    $99 zoom lens to give pro quality results. It is not going to happen.
    columbotrek, Aug 29, 2004
  15. This is not always true.....The 75-150 mm "E" type Nikkor zoom, used in the
    80's by professional fashion photographers in New York, can be had used
    today for $99. (approximately) If you are willing to do some research, and
    look for what you want with some patience, you can get really good buys, but
    it helps to have a camera that can work with old glass.......
    William Graham, Aug 29, 2004
  16. Mike - EMAIL IGNORED

    Dallas Guest

    Yeah, automatic transmission is for sissies!

    Every car I have ever owned has been manual. I don't think I would know
    what to do with my left foot if I ever drove an auto.
    Dallas, Aug 29, 2004
  17. Mike - EMAIL IGNORED

    Alan Browne Guest

    When I travel to Europe, I can rent a manual. When I travel to
    the US (or elsewhere in Canada) renting a manual is pretty much
    Alan Browne, Aug 29, 2004
  18. It is *always* true... of *new* lenses. And assuming the pro in "pro
    quality" is a pro involved in photography that, for whatever reason, demands
    high resolution low distortion low falloff imagery. And assuming you didn't
    just get incredibly good discount on a Leica 35-70 f2.8 R lens.
    Martin Francis, Aug 29, 2004
  19. Mike - EMAIL IGNORED

    Bob Hickey Guest

    I can pick holes in his approach and conclusions in numbers of
    As a 62 yr. old guy whose eyesight is about as good as can be expected, I
    find it much, much easier to focus an MF camera, w/ the correct diopter than
    an AF. By the time I get done argueing with the stupid thing, it's all over.
    I will agree that the finders are much brighter than a fresnel screen, but
    the fresnels "snap in". No doubt about in or out. The AF mirrors just slowly
    get better. Plus, of course, they tend to look for something vertical and
    contrasty, which may be great for football, but not so good for scenery. As
    far as racking the focus back and forth on a med. format, that becomes a
    habit. No matter what you tell them, people move. They just do. And the
    closer you stand, the faster they go. Between the blinkers, the spinners,
    and the guy who had a couple for breakfast, racking becomes more of an art
    form than the shot. And you can't teach an AF to get a bigger lite and focus
    in front of the shot. As far as lenses go, I just don't see plastic being
    as good as glass, period. Bob
    Hickey www.pbase.com/bobhickey/galleries
    Bob Hickey, Aug 29, 2004
  20. Mike - EMAIL IGNORED

    Colin D Guest

    OK, Bob, I guess you're somewhat better off with your sight than
    others. If a correction lens (diopter) fixes it for you, that's great.
    The great majority of people who need correction lenses also suffer from
    some degree of astigmatism, and no simple 'diopter' can correct for
    that. They need a prescription lens from their optician, and that
    raises problems when rotating the camera from landscape to portrait. Or,
    they just wear their glasses with the camera, which can be a damned

    Due to early cataract formation (too much RF from my ham radio days?) I
    have had the lenses replaced in both my eyeballs, so now they are 'fixed
    focus' eyeballs. With the proper correction at the proper distance, I
    can see better than most - but if things are out of focus, then that's
    it. AF is my saviour. Having said that, though, it doesn't often miss,
    and the camera (300D) will focus well down to about EV 0.5 without
    supplementary light.

    Colin D.
    Beware the Pontificators. They are rarely Performers.
    Colin D, Aug 29, 2004
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