Faster autofocus - what's available?

Discussion in 'Nikon' started by RaymondC, Nov 12, 2017.

  1. Here is a jpg obtained with a screw-drive lens + teleconverter from this year's air show:
    [​IMG]
    No cropping or sharpening, just a bit of exposure adjustment.
     
  2. If hunting, not locking AF is the problem, I recommend a red grid projecting flash or, if you are determined to skip flash, something like a Yongnuo remote doing the same job but weighing less. During a recent event I noticed gaining some AF speed from using mine (with EOS 5D IV & f2.8). As long as you aren't switching to something with face or even eye detection, you'll still need time to select proper AF spots and or (back button?) focus & recompose. Continuous AF seems handy to deploy in low light with people standing around since you or them are still likely to move out of DOF.
    Af assist red light patterns will get noticed but should be less annoying than white light and people will see you photographing anyhow, so they should be likely to bear with it.
     
  3. With disclaimers about having little experience with the D600 and your lenses, let alone this shooting scenario...

    In awkward focus situations, I'm a fan of AF-On (back-button focus) with AF-C. To try this on a D600, use menu f4 to assign AE-L/AF-L to AF-ON, then the camera will only try to focus while you're holding down the AE-L/AF-L button (not when you press the shutter). If the camera is tracking successfully, I keep the button pressed to allow for subject movement (or me swaying); if it's struggling, I prefocus, wait until it locks, then take my thumb off and shoot separately (often with a little extra DoF). It won't make the camera track better (and it's not quite so good at confirming when you've actually locked focus - it won't automatically stop like AF-S), but it'll give you better control over when it gives up.

    Just a thought; worth a try, if you haven't.

    I defer to others about the AF assist lights, but as Dieter says, it doesn't sound that dark, unless you have very low-contrast subjects.
     
  4. Yes, I do use the AF-ON button, by switching it from the AE-L/AF-L. The lens in those situations just hunt and hunt. When you look thru the viewfinder it goes a 360 circle the whole viewfinder is blurred out.

    I guess I could prefocus but I often shoot at F2.8 or F4 due to the light levels and I still at 1/60'ish.

    I tried the AF-assist red light with my SB800 - works a lot better. I probably do have low contrast. When they are on the stage it is fine but when they go into the baptism pool the clothing they were are often all black or very dark tones and then it gets all wet, their faces are also wet as well, wet hair etc. The pool is also in the corner of the room. Few available light as all the curtains are drawn some some tungsten lights indoors obviously not bright.

    It's not a sprinkle of water well for those who are older and have illnesses, the others they walk into a pool and dip their heads in the pool and then walk out afterwards. Black top, black pants or if a dark blues etc ...
     
    Last edited: Nov 14, 2017
  5. As Deep Thought would say... "hmm, tricky". I'm glad the AF assist is helping. I've been known to resort to live view when the AF is really struggling, but it's tricky with a moving subject. I often try to find a nearby high-contrast edge (usually edge of face against the background) and rely on depth of field to cover the eyes - but for me, the problem is often shaded faces with a bright background, so there's something near the plane of focus that I can find. For what it's worth, I find a lot of people are still moving at 1/60, so I tend to find myself pushing the shutter speed (and therefore ISO) a little more; third-party software can do quite a good job of denoising, but motion blur is a pain. It may not matter so much either way at smaller sizes, though.

    If the subject is wet and you don't want to use the speedlight AF grid, I'd suggest a small and fairly bright LED light (I have a Thrunite Ti3 that runs of a AAA; I can also recommend the Fenix LD02 - other small and bright flashlights are available, but there's a big difference between the premium models and the no-name versions). It's got different brightness levels, the brightest of which is pretty decent (especially for its size), and you can put a fairly subtle highlight on a wet subject, which should give the AF system something to lock onto. Just thinking it might be less obtrusive than a bigger or brighter light source - and you might get some catchlights in the eyes. They're only a few dollars if you want to try it.

    For what it's worth, I think I'd be expecting any of the MultiCAM 3500 cameras to behave a bit better than you're suggesting, especially with an f/2.8 lens, but it's hard to say without being there. I'm sure others here have more experience in challenging shooting scenarios than I do, so I'd take their advice over mine. :)
     

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