Could not figure out how to copy from the PDF so I grabbed a screen capture :)
If you can understand this stuff without getting confused I would love to hear from you.
How is focusing the subject different from focus tracking?
#2and #3 would seem to mean that for the 1st image in a series while you are in AI Servo AF that the shutter will release even if the system detects that the subject is not in sharp focus. Is that correct?
With regard to the the second and future images in #2 are they saying that the camera will fire as fast as possible no matter what?
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"At 8 frames per second, the camera has a limited amount of time between each shot to focus the subject. C.FnIII-2 allows you to change how the camera prioritizes focussing versus taking shots.
Setting 0 means the camera will concentrate on focussing and tracking the subject for the first and all subsequent shots. This means that the shooting speed may be affected if the camera is struggling to obtain focus and track the subject.
Setting 1 means the camera will prioritise focus and tracking for the first shot in the sequence, then after that give priority to shooting at 8fps (at the expense of focus accuracy)
Setting 2 means the camera will concentrate on maintaining 8fps at the detriment of focussing.
Setting 3 means the camera will take the first shot immediately (to the detriment of focus if necessary) and then prioritize focussing over shooting speed for all subsequent shots in the sequence."
And this:
"even though the camera sounds like it's just mindlessly letting the shutter flap away at 8fps, servo af tries to time the shutter with when it THINKS the subject is in focus. At times this will slow down the AF slightly, on occasions it will slow it down quite a bit.
Tracking priority is responsible for that bevaviour. If you change it to shutter priority you will get a higher fps in certain situations.
The key to this cfn is that the tracking priority holds back the fps for what IT THINKS is in focus, and as we all know cameras can and do get it wrong in that regard.
With some situations or techniques it is possible that drive priority will yield more in-focus shots in a burst (entirely down to the fps).
Personally i prefer to use tracking priority as i find i get more keepers (for me that usually always means birds in flight). It's entirely a personal and situation dependant setting though. I'd advise trying both and see what works for you."
Thanks Patrick. I am gonna study your post and will get back to you tomorrow.
When you say, "Personally i prefer to use tracking priority as i find i get more keepers" which # are you referring to?
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Check out the new SONY e-Guide and videos that I did with Patrick Sparkman here. Ten percent discount for BPN members,
Just to clarify, this is a quote from a DPReview thread, so the "Personally....." was not me. I do not have a 7D, but did a net search to find this explanation. I do think he is referring to setting 0 though.
Patrick, Thanks on all counts. In part is seems that we are to believe that if the system is set up for focus priority that it will focus on the eye and if it is set up for drive speed that it might not focus on the eye.
I believe that there will be lots of times when the first image will not be sharp even though one has selected focus priority and lots of times when it will be sharp even though you have selected speed....
Am as still at a loss on this: How is focusing the subject different from focus tracking?
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Check out the new SONY e-Guide and videos that I did with Patrick Sparkman here. Ten percent discount for BPN members,
Again, sorry to have been away for so long :) Been working on User's Guide updates for the MIV and the 7D, on a long Bulletin, and on several other big projects.
IAC, I spoke at length to Rudy Winston, one of Canon's top tech reps.
Here is my further understanding:
When in AI Servo AF and you are shooting continuously, 3-2: 0, the default, means that the first image will not be taken unless the system is tracking it well and sees the subject as sharply focused. With subsequent images, the system will--if need be--spend a bit more time tracking and focusing the subject accurately than if you select either 3-2: 1 or 3-2: 2.
When in AI Servo AF and you are shooting continuously (holding down the shutter button) setting 3-2:1 means that the first image will not be taken unless the system is tracking it well and sees the subject as sharply focused but that subsequent images the camera will continue firing at the maximum frame rate whether or not it sees the subject as sharp and whether or not it is tracking accurately.
When in AI Servo AF and you are shooting continuously (holding down the shutter button) 3-2:2 tells the camera to release the shutter the instant you depress it and to keep on firing at the maximum frame rate whether or not it detects accurate focus and is tracking accurately.
When in AI Servo AF and you are shooting continuously (holding down the shutter button) setting 3-2:3 tells take the camera to take the first shot immediately (to the detriment of focus if necessary) and then
to sacrifice shooting speed for more accurate focus tracking and and sharpness.
All of the above is in agreement with Patrick's quote above. For photographing birds in flight I would agree that if the system works as designed, that either 3-2:0 or 3-2: 3 would be best. As I always try to sense that the system is tracking well before fully depressing the shutter button, it would seem that the results from either would be quite similar for me.
Do remember that comparing results with the different settings is pretty much impossible as there are simply way too many variables involved. Can anyone say "crap shoot"?
BIRDS AS ART Blog: great info and lessons, lots of images with our legendary BAA educational Captions; we will not sell you junk. 30+ years of long lens experience/e-mail with gear questions.
BIRDS AS ART Online Store: we will not sell you junk. 35 years of long lens experience. Please e-mail with gear questions.
Check out the new SONY e-Guide and videos that I did with Patrick Sparkman here. Ten percent discount for BPN members,
For most BPN and action photographers, you'll want Option 0.
This is what Option 0 will attempt to do:
- For the first image, if the focus is not yet acquired, the camera will attempt to delay taking the first shot for a very short period to try to acquire focus and then it will release the shutter when focus is acquired or when it hits some pre-defined (internal) timeout.
- For the second and subsequent images, while still holding down the shutter release, the camera will put a priority on acquiring/maintaining focus and will slow down the frame rate somewhat to do so.
You can hear the camera firing just a little slower during those times when it is trying to (re)acquire focus.