Manual focus - when is it useful?

Discussion in 'Beginner Questions' started by analox, Nov 27, 2008.

  1. This question comes to my mind when I was discussing with a friend who uses Olympus OM lens (manual focusing
    lens). To me, auto-focus is much faster & easier to use. Rotating the focusing ring & see through a small
    viewfinder to know when you get it right is difficult and mostly inaccurate for me (!). Yet, things usually come
    in 2 sides, there should be cases when manual focus shows to be useful. What do you guys think? Please help me
    name some examples (hah, I can hear some "low-light photography" whispered :D)

    Well, I go first with the trick of "focusing lock": you get the focus right by auto-focus (with flash assisted if
    necessary), then switch to manual focus immediately. By this, the focus now is locked at the "correct" position.
    It's similar to the idea of locking exposure. Focusing lock would be useful in the case of low-light situation,
    you don't want flash and the camera auto-focus just confuses. You can turn on flash assisting + auto-focus to get
    it right. Then lock the focus, turn off our flash, and take the shot :)

    Now, your turn :p...

  2. Manual focus is good for multiple reasons:
    • it doesn't use power - saves battery
    • sometimes the depth of field is so shallow that autofocus doesn't easily give you the point you are looking for
    • in low light I find that I can sometimes focus where the autofocus sensor cannot.
    • on any subject without a distinct edge, autofocus has difficulty (for instance a gray wall)
    • if you want to purposefully front or back focus a subject to make their features less-distinct without going totally out of focus
    • the lenses tend to be cheaper
    • I can use manual focus lens on a mechanical film camera and shoot almost anywhere without concern about being away from a power source for too long
    there are probably more but that is what jumps to mind.
    James Photography RI
  3. Well, let me put some of my points (those that have not been mentioned):

    - For some certain categories of photography, MF is more favored. E.g., shooting macro where you almost cannot use AF effectively.

    - I have once heard about focus lock delay. It refers to the time when you press half-way the shuttle and wait until the focus is locked, then you fully press it to take the photo. Now for example that you are shooting sport, you frame (and focus) your camera, wait for smthing or smone appear in the frame, then you shoot. Clearly, you don't want the focus delay.

    - Yes, power saving is a reason

    - Last but not least, MF is about a style. You just feel love shooting with MF, not AF, you enjoy focus using your own hand and eyes, not with some noisy motor ;)

    Quang Huy
  4. with manual focus, you focus on what you want in focus. with auto, the camera makes the decision for you. as you shoot more, you'll find that there are times when each method has a distinct advantage for one reason or another, including those reasons already stated above. seeing through the viewfinder comes with time, and most slrs have optional viewfinder screens with manual focus aids such as split prisms, etc, to increase your accuracy. the camera does not always make the same decision you would make, but again this may be hard to appreciate until you have done quite a bit of shooting and start to see the limitations of the autofocus feature.
  5. "Rotating the focusing ring & see through a small viewfinder to know when you get it right is difficult and mostly inaccurate for me (!)"

    Mount the lens on OM-1 and try again. ;)
  6. Thank you all for your responses :). Very much appreciate some new insights about manual focus that I got from here!

    Besides, I'm also interested in the situation (or your experience on "when") that we can take the advantages of manual focus into actions. Here we got "hard-to-focus" objects in low-light or macro photography, actions in sports. What else?

    @Kari Vierimaa: oh, I forgot to mention that my friend use OM lens on his E510 with OM-adapter. Hope I'll have a chance to try on OM-1 in the near future :-? :D
  7. I used manual focus for almost 30 years before getting my first autofocus SLR. So I was already accustomed to manual focus for action oriented photography (photojournalism, sports, street, documentary, etc.). That probably biases my opinions.

    In some cases my autofocus SLRs can lock focus quicker than I can manually. But in tricky situations - dim lighting, low contrast subjects - I prefer to use a compromise method. With AF-S Nikkors I can use the AF-ON button (rather than the shutter release button also controlling AF) on the camera to control autofocus, and still tweak focus manually in tricky situations. When I press the shutter release button I don't need to worry about changing focus when I recompose.

    Other times I'll assign AF to the shutter release button and use AF only. Just depends on the situation. There's no need to confine myself to one technique that won't work well in every situation.

    Camera and lens systems vary, BTW. For example, the hybrid auto/manual focus technique doesn't work so well with older screwdriver type AF Nikkors and third party lenses. It's not good to manually force the mechanism when manually focusing and flipping the switch from auto to manual focus is awkward when in a hurry. No such worries with AF-S Nikkors and comparable lens designs. Just depends on your equipment.
  8. SCL


    I primarily use manual focus on my DSLR when I'm shooting macros, or looking for a particular plane of focus in narrow depth of field shots (think long telephoto lenses). All my other cameras are manual focus, so the issue is no big deal. I wondered for years why people were so lazy that manufacturers thought they needed to incorporate auto-focus. As my eyes age, I can appreciate its occasional benefits, although I think with the brighter viewfinders of pre-AF cameras, and a split screen...that focus is often more precise than with AF cameras.
  9. A lot of excellent advice. I rarely use AF (after 30+ years of MF cameras) and only then I use the star button for AF lock so
    the shutter button won't effect it. I tend to keep the subject or point of focus off center so it's easier to manually focus on
    use AF to lock it.
  10. Another situation in which autofocus can be almost useless is for furry or feathery wildlife sitting among lots
    of twigs, sticks and branches. Unless your camera is very smart, the fuzzy texture of the animal compared to the
    straight lines and high contrast of the twigs will often deceive it and cause it to focus incorrectly on the
    latter and not the subject you're actually aiming for.

    To get the most out of manual focus, you really need an slr with a bigger viewfinder and a better focusing screen
    than the standard offerings in many digital bodies. There are some forms of mixing the benefits of manual and
    autofocus that can compensate for small viewfinders and featureless screens though.

    Sometimes it helps if the body can confirm focus while you are the one who turns the focus ring, although in that
    case you're still dependent on the accuracy of the camera's focusing algorithm. Another option is setting your
    camera to an AF mode that focuses first and then releases the focus drive and allows you to adjust fine focus
    manually (without you having to actually switch off the AF). The latter can help speed things up compared to
    manually moving from (say) infinity focus to a bird landing 5 meters from you.
  11. I agree 100% with Paul De Ley. I have seen many folks with very expensive totally automatic cameras (usually digital but that is not the issue here) have photos ruined when taking exactly what Paul described: A animal nicely framed by tree branches, but the AF chooses the branches not the animal. These folks (as we all do!) "forget" their user guides. And the AF noise (and SLR mirror) often scare the animals; I have also heard that the infrared used for distance can bother them as well. We carry Leica M6 rangefinders, so quiet I think the CIA could use them!. Almost completely manual, however I rarely lose a shot. Bright high altitude day in Northern New Mexico, orange filter (we shoot B&W) and f/8 at 1/500 usually does the trick.

    My girlfriend went to Namibia and usually had to be the first to shoot before the AFs scared the critters away. She does have a series of four shots of an elephant charging the vehicle. The AF weren't going to scare this guy away! She had the camera set at f/8 1/500 (good depth of field!) and despite her hands shaking from fear she got all the shots, and a "butt shot" as it walked away. The elephant could have easily tipped the Rover over! I guess he decided it wasn't "cute enough". She called me from Namibia after the adventure and said "I really hope these came out!"

    We were in Yellowstone a year ago (if you get to the west you must go - single car entry was about $25 for a week and good at both Yellowstone and the Tetons with unlimited "in and out". I was standing by a road on the way into Montana and she said "look behind you!" and snapped a shot as a 1500lb Bison sauntered past me about 15 feet away. On tarmac and totally silent. The Leica didn't phase him.

    I am not against AF. Perfect for busy crowd scenes (such as riots!).
  12. There are times when flash (focus-assist or otherwise) simply aren't an option. I've often found myself in a museum or
    archive photographing a sensitive document or artifact. It's almost always in low-light where autofocus has problems
    anyway *and* flash is not allowed, period.
  13. In addition to everything said above, using manual focus on a short prime lens with "old fashioned" markings will permit hyperfocal distance focusing. You can dramatically increase the depth of field in photographs that are focused this way. Unless your camera is really quite advanced, you cannot easily (and perhaps not at all) set focus this way using auto-focus and you thereby lose a great deal of the capacity of the lens.
  14. I concur with pretty much everything above. I suppose nowadays it may be a matter of preference.

    When would I use manual focus? All the time. I owned a camera with autofocus, briefly, in the 90s. I sold that thing off
    after about a year. It beeped all the time. Also, the "focus lock" operation that seems easy to use for you, was a royal pain
    for me.

    At the time I spent three times as long taking a quick snap. It took longer to operate the auto-everything camera
    because I was having to switch off or override a bunch of functions I didn't want. Back then, the cameras were so user-
    un-friendly that one couldn't even turn off that annoying beeping noise I mentioned earlier. Maybe autofocus is better
    today. Meanwhile, previous experiences with "improved" technology generated so much fuss over the years that a lot of
    times, to me, it seems like nonsense I just don't need.

    My question would be the converse. Why would someone use autofocus? Maybe an Edgerton-style science photo. I
    would imagine that even in sports the autofocus might pick the wrong target. Same for auto-aperture. Am I supposed to let the camera
    pick my depth of field?

    Think about it like this. The auto-everything lens with the robots and relays and sensors built into it can easily run $500
    or more. If you turn the dial yourself, it's common to buy a manual lens with the same quality of glass in it for $120.

    I use manual focus lenses when I don't want to pay four times as much for a robot to turn the focus ring for me.
  15. I find manual focus to be much more dependable and accurate than autofocus. In addition to my own work, I hire photographers for my day job in PR and function as picture editor looking at the work they turn in. Back in the days of manual focus, there might occasionally be an out of focus frame if looking at a contact sheet that showed everything a photographer shot, but they were the exception rather than the rule. When looking at slides or prints where the photographer had the chance to weed out his bad shots, you never ever saw an out of focus picture. But today looking at digital I'm shocked at the number of out of focus and soft focus images I see. Most of them fall into the realm of soft rather than blatantly out of focus. They look OK at normal size on the screen but when you zoom in on "actual pixels" to check focus, they're soft. This isn't a digital vs film issue. With digital images that are in focus, you go in on "actual pixels" and they're tack sharp the way they are supposed to be. I'm convinced that the issue is that photographers are relying on auto focus far too much and accepting whatever it gives them. Sometimes the AF sensor hits the subjects eye where it is supposed (focus on people is almost always supposed to be on the closest eye) but sometimes it misses and focuses on the nose, ear, chin, shoulder, etc.) This can happen with manual focus but is much less frequent because the photographer can see in the camera if the shot is in focus or not and -- most importantly -- is paying attention to focus. There are certainly times when autofocus helps and I used it frequently myself. But just like anything else it has to be used with skill to get good results.
  16. In my view it's all about the degree of control one is permitted over the picture-making process. If you're using a small-sensor system, short focal lengths, with intrinsically wide depth of focus, then you can, in many circumstances, get away with letting the camera decide for you, since the acceptable range of focus is wide enough to be arbitrary. But for larger sensor cameras and/or telephoto lenses, you need to control where the preferred zone of sharpest focus is being placed at.

    Yes, you can let autofocus decide for you, then confirm by taking the shot and chimping the results (or not, depending on how small your LCD screen is), or simply trust the system to get good focus and find out afterwords (like what we did with autofocus film SLRs.) But if you believe that selective focus is an important part of photography (which I believe it to be fundamentally important) then you need to intervene and control that quality of the image yourself.


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