Focus modes for fast moving objects

M38A1

What are the ideal focus modes when shooting fast moving objects like aircraft (airshows) or vehicles (car racing)? I don't want to try it out at an event and have them all be out of focus.

Is the Auto-continuous preferred over Auto-single?

Equip: Nikon D90

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Icebear

Well, single mode may insure you have no OOF shots, but it could also insure you have no shots at all. I'd use dynamic area AF in predictive continuous mode if you have it.

M38A1

Icebear wrote: »

.... I'd use dynamic area AF in predictive continuous mode if you have it.

......stumbles off to find the manual.

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jfriend

I'd suggest you read this writeup on setting up a D300 for action shooting. The D90 doesn't have quite all these settings, but it gives you an idea how you want to set things up:

http://johnfriend.blogspot.com/2009/10/nikon-d300-auto-focus-for-sports-i.html

Macushla

jfriend wrote: »

I'd suggest you read this writeup on setting up a D300 for action shooting. The D90 doesn't have quite all these settings, but it gives you an idea how you want to set things up:

http://johnfriend.blogspot.com/2009/10/nikon-d300-auto-focus-for-sports-i.html

Thanks for that link!

One thing I learned while shooting sports with the d90 is to shut off the VR on your lens if you have it. Someone told me that it doesn't work great when your are shooting multiple frames per second.

Icebear

Yeah, and you should probably be shooting at a high enough ss that VR is just a redundant battery waster, even if it does not degrade your shot.

WernerG

D90 using AF-A or AF-C
Thanks for starting this thread. I have the same issue. I occasionally have opportunities to shoot birds in flight with the D90 and have been using this set up;

Dynamic Area, AF-A, center focus area = Wide, 4.5 f/s burst mode, S mode @ 1200/sec (usually)

Thom Hogan's guide to the D90 claims that the Nikon manual discussion on focus modes is poorly worded. AF-A is not an automode that switches between AF-C and AF-S depending on the subject's motion; it is really a mixed mode that had properties of each all the time.

AF-S focus priority, no focus tracking (does not shoot until focus is achieved, but subject can move out of focus)
AF-C shutter priority, focus tracking (will shoot when shutter is pressed even if not currently in focus)
AF-A focus priority, focus tracking (will not shoot until focus is re-acquired even if shutter is pressed)

Of course, all these modes require the photographer to be on-target. That's the skill part and it is not easy.

Given these choices I have been opting for AF-A, reasoning that if AF-C shoots on shutter press irrespective of current focus, there is no real value in having an out-of-focus shot, albeit perfectly timed. I do not notice any real delay between shutter press and the camera's response in AF-A. The 70-300mm zoom that I have is pretty quick to focus, especially when it starts close to focus. In burst mode the only delay occurs when the buffer fills up when writing raw files.

This setting apparently does not agree with the link referenced above. For the D300 the recommendation is to not require focus lock before the shot is taken. That's worrisome. I've tried AF-C while shooting skiers and was not happy with the results, most were out of focus.

Although I've gotten many nice BIF shots, I don't think my success rate in getting well focused BIF's with AF-A is all that good either. It could be because I've been keeping the VR on and it may be fighting me. Like the OP I am reluctant to experiment too much because I don't get that many opportunities to do BIF's and I don't want to waste an opportunity. I also blame it on the fact that the D90 only has 11 focus sensors as opposed to the zillion that the full frame cameras have.

The wide setting for the center focus area probably would not be good in an environment with busy background, but for most of the BIF's that I have done the background is the sky.

I hope this is useful.. Please let us know how you do and how you set the camera up.

Werner

jfriend

WernerG wrote: »

Thanks for starting this thread. I have the same issue. I occasionally have opportunities to shoot birds in flight with the D90 and have been using this set up;

Dynamic Area, AF-A, center focus area = Wide, 4.5 f/s burst mode, S mode @ 1200/sec (usually)

Thom Hogan's guide to the D90 claims that the Nikon manual discussion on focus modes is poorly worded. AF-A is not an automode that switches between AF-C and AF-S depending on the subject's motion; it is really a mixed mode that had properties of each all the time.

AF-S focus priority, no focus tracking (does not shoot until focus is achieved, but subject can move out of focus)
AF-C shutter priority, focus tracking (will shoot when shutter is pressed even if not currently in focus)
AF-A focus priority, focus tracking (will not shoot until focus is re-acquired even if shutter is pressed)

Of course, all these modes require the photographer to be on-target. That's the skill part and it is not easy.

Given these choices I have been opting for AF-A, reasoning that if AF-C shoots on shutter press irrespective of current focus, there is no real value in having an out-of-focus shot, albeit perfectly timed. I do not notice any real delay between shutter press and the camera's response in AF-A. The 70-300mm zoom that I have is pretty quick to focus, especially when it starts close to focus. In burst mode the only delay occurs when the buffer fills up when writing raw files.

This setting apparently does not agree with the link referenced above. For the D300 the recommendation is to not require focus lock before the shot is taken. That's worrisome. I've tried AF-C while shooting skiers and was not happy with the results, most were out of focus.

Although I've gotten many nice BIF shots, I don't think my success rate in getting well focused BIF's with AF-A is all that good either. It could be because I've been keeping the VR on and it may be fighting me. Like the OP I am reluctant to experiment too much because I don't get that many opportunities to do BIF's and I don't want to waste an opportunity. I also blame it on the fact that the D90 only has 11 focus sensors as opposed to the zillion that the full frame cameras have.

The wide setting for the center focus area probably would not be good in an environment with busy background, but for most of the BIF's that I have done the background is the sky.

I hope this is useful.. Please let us know how you do and how you set the camera up.

Werner

The recommendation of using release priority on the D300 is because at max fps, the D300 will often stutter between shots while it confirms that the next shot is in focus - even if it is already in focus (which it probably will be if focus was acquired on the first shot and you have good tracking technique). So, if you want to shoot at max fps on the D300 in all circumstances, then you need to shoot in release priority. I know this from shooting thousands of birds-in-flight shots and tens of thousands of soccer shots.

I don't have experience in this regard with the D90, but the place to look for the issue is when holding down the shutter at max fps.

I understand the notion that you don't want to end up with an out of focus shot since that is worth nothing. But, the issue for me has been waiting for the camera to confirm that the shot is indeed actually in focus when it actually is because it's tracking from a previous shot that was in focus.

It should just take some experimentation in the appropriate conditions with your D90 to see what works best for you.

On my D300 shooting soccer, I get >95% focus keepers when using release priority. The three main reasons I lose a shot are: 1) it locks focus on the wrong subject (my own focus targeting error) or 2) I don't track successfully and focus moves to something else or 3) an intervening object disturbs the targeting.

WernerG

Thanks for the explanation for the D300 settings. When I first got the D90 and read Hogan's explanation of the AF modes I did a rather silly test. I started on AF-C and burst mode, selected a brightly lit, contrasty subject and ran toward it, holding the shutter down. In AF-C the camera fired in a regular pattern until the buffer filled but they were all out of focus. In AF-A, the camera fired once when I started but then fired sporadically until I stopped moving then became regular, until the buffer filled. But those few shots were sharp.

That at least confirmed Thom's explanation for me. Of course the camera was bouncing around while I ran and I wasn't really measuring anything but that test was at least an indication of how the two modes differ.

I think for my next action or BIF opportunity I will definitely remember to turn VR off. It is probably trying to counter my motion although the manual says that it detects panning and doesn't fight it. And I should try AF-C again.

Thanks for the explanation.

Werner

jfriend

WernerG wrote: »

Thanks for the explanation for the D300 settings. When I first got the D90 and read Hogan's explanation of the AF modes I did a rather silly test. I started on AF-C and burst mode, selected a brightly lit, contrasty subject and ran toward it, holding the shutter down. In AF-C the camera fired in a regular pattern until the buffer filled but they were all out of focus. In AF-A, the camera fired once when I started but then fired sporadically until I stopped moving then became regular, until the buffer filled. But those few shots were sharp.

That at least confirmed Thom's explanation for me. Of course the camera was bouncing around while I ran and I wasn't really measuring anything but that test was at least an indication of how the two modes differ.

I think for my next action or BIF opportunity I will definitely remember to turn VR off. It is probably trying to counter my motion although the manual says that it detects panning and doesn't fight it. And I should try AF-C again.

Thanks for the explanation.

Werner

My experience has been that the "in-focus-ness" of a sequence is all about two things:

1) Acquire good focus on the subject BEFORE you press the shutter
2) Have good tracking technique to keep one of the cross hatch sensors on your subject.

If I can do those two things, my entire sequence will be in focus even at 8fps, even when the subject is moving even when I'm in release priority. The camera seems to be good at tracking and doing predictive focus if you acquire good focus before you start the sequence. If you don't get good focus before the sequence, then all bets are off - it's probably not going to suddenly lock on during the sequence and odds are the whole sequence will be bad.

My theory is that before the sequence, the AF sensor is getting a constant stream of data because the mirror is down and real-time data is flowing to the AF sensor. After you start the sequence, the mirror is flipping up/down and the AF sensor is only getting sporadic pieces of data for the few milliseconds that the mirror is down.