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06-13-2010, 01:52 PM   #16
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QuoteOriginally posted by opiedog Quote
that's what i don't understand. i thought in AF-C, the shutter will fire even if the subject is not in focus so in theory, the kx should be able to do 4.7fps, but it doesn't
We were talking about the K-7 but actually there are few differences between the 2 cameras. AF-C will fire even if not in focus, at least on the first shot, on a burst series the camera will try to focus between shots which is most of time what you really want. I of course prefer 3fps with good focus than 5fps of OOF shots.

06-13-2010, 03:49 PM   #17
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QuoteOriginally posted by opiedog Quote
that's what i don't understand. i thought in AF-C, the shutter will fire even if the subject is not in focus so in theory, the kx should be able to do 4.7fps, but it doesn't
This is a common source of confusion.

It appears to me that with most brands, AF.C is sort of a compromise between accurate and fast refocus between images. One could imagine several settings for AF.C, with preference on accuracy, speed, max. amount of motion between shots etc. and some brands actually offer a couple of parameters. Unfortunately, Pentax only offers 1 parameter: on or off

Putting numbers into it, it appears to me that the K-7 invests between 100ms to 300ms to refocus between frames in AF.C and about 200ms to 1500ms to focus for the first frame in AF.S.

It can make sense to shoot a high speed burst in AF.S and refocus (retrigger) once per second.
06-13-2010, 05:14 PM   #18
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I think Canon or Nikon, or both, allow a user to stipulate what prioirity the camera should use when using a high frame rate and continuous focus, either focus priority (so it only fires when in focus) or shutter priority (so it just fires, whether or not focus has caught up).

It's a good idea.
06-14-2010, 04:25 AM   #19
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QuoteOriginally posted by Arpe Quote
I think Canon or Nikon, or both, allow a user to stipulate what prioirity the camera should use when using a high frame rate and continuous focus, either focus priority (so it only fires when in focus) or shutter priority (so it just fires, whether or not focus has caught up).

It's a good idea.

let's hope that becomes a feature in the next Pentax DSLR .... coming this photokina

06-18-2010, 12:12 PM   #20
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QuoteOriginally posted by falconeye Quote
Putting numbers into it, it appears to me that the K-7 invests between 100ms to 300ms to refocus between frames in AF.C and about 200ms to 1500ms to focus for the first frame in AF.S.
Have you ever looked into accuracy difference for static targets? Is AF.C exactly as accurate as AF.S if given plenty of time for a static object?

If so, I could leave my camera in AF.C, assign focus to the OK button (K100D) and have the best of both worlds: short press (keep pressed until the focusing stops) for "AF.S" and continues press for "AF.C". I realise that there would still be a difference between shutter and focus priority but I'd be fine with that as long as I don't lose any accuracy by not using the true "AF.S" mode.
06-18-2010, 03:01 PM   #21
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QuoteOriginally posted by Class A Quote
Have you ever looked into accuracy difference for static targets? Is AF.C exactly as accurate as AF.S if given plenty of time for a static object?
That may be a good research topic for LumoLabs

No, I didn't. I assume AF.S to be more accurate, esp. in rather difficult situations.
06-19-2010, 04:36 AM   #22
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QuoteOriginally posted by falconeye Quote
I assume AF.S to be more accurate, esp. in rather difficult situations.
I hope LumoLabs will attempt to rigorously check whether such a shot from the hip can be supported or not.
06-19-2010, 05:00 AM   #23
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QuoteOriginally posted by Arpe Quote
I think Canon or Nikon, or both, allow a user to stipulate what prioirity the camera should use when using a high frame rate and continuous focus, either focus priority (so it only fires when in focus) or shutter priority (so it just fires, whether or not focus has caught up).

It's a good idea.

The best way to solve this problem is to assign autofocus to the AF button. That way you can choose if you want the camera to focus or not during a burst.

I did this on my D700 and my K7's.

06-19-2010, 05:28 AM   #24
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QuoteOriginally posted by JMI Quote
The best way to solve this problem is to assign autofocus to the AF button. That way you can choose if you want the camera to focus or not during a burst.
I don't quite understand.

If I assign AF to the AF button, I won't focus when I press the trigger. Understood. But I thought it applies to single shots only.

Do you mean that with the mappig, during AF.C operation, the camera refocusses between shots when I simultaneously press AF, and keeps static focus when I don't? On/off during a burst? If so, good find!

And if so, would assigning the AF button to "No AF" imply that AF.C refocus is suppressed while I simultaneously press AF? That would be cooler even ...
06-19-2010, 06:12 AM   #25
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Also make sure that CA and distortion correction are off.
06-20-2010, 06:19 PM   #26
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QuoteOriginally posted by falconeye Quote
Do you mean that with the mappig, during AF.C operation, the camera refocusses between shots when I simultaneously press AF, and keeps static focus when I don't? ...
would assigning the AF button to "No AF" imply that AF.C refocus is suppressed while I simultaneously press AF?
That's what my K100D does and that's why I find AF.C so useful.

I would have thought you are the type who reads manuals.
06-21-2010, 05:33 AM   #27
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QuoteOriginally posted by Class A Quote
I would have thought you are the type who reads manuals.
Yes. Programming language reference manuals
06-21-2010, 01:28 PM   #28
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QuoteOriginally posted by Arpe Quote
I think Canon or Nikon, or both, allow a user to stipulate what prioirity the camera should use when using a high frame rate and continuous focus, either focus priority (so it only fires when in focus) or shutter priority (so it just fires, whether or not focus has caught up).

It's a good idea.
I think they both even offer a "high speed burst" mode in which AFC cannot be used, but eliminates the mirror flip between shots. Not sure about that, but both list two different burst modes.
06-22-2010, 07:52 PM   #29
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QuoteOriginally posted by falconeye Quote
Yes. Programming language reference manuals


I like the one for Smalltalk. Does it fill a page?
The library needs a bit more documentation...
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