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08-22-2015, 07:02 AM   #1
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Refocusing in Interval Composite mode

Hi eveyone!

I'm testing the Interval Composite mode and I noticed something strange:

The camera tries to refocus between each shot. This is strange, since I'm using the "back button focus".

Am I missing a setting?
The easies workaround is to turn the lens/body to manual focus, but I probably won't remember to do this, since I usually use the AF button to focus.

08-22-2015, 07:16 AM   #2
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it will focus for that shot only....then refocus every shot thereafter I believe...that's why manual works
08-25-2015, 07:49 AM   #3
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Focus on the subject before starting the interval, then move that litle button from the left side to MF. If it's dark it will try to focus before every shot if you let it on AF. I also use the back button focus, but the camera still want to focus on something bright or closer.
08-25-2015, 10:02 AM   #4
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Thanks,
Yes, I know the technique, but I found the behavior rather strange...

08-25-2015, 11:11 AM   #5
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QuoteOriginally posted by Azergoth Quote
I found the behavior rather strange...
You stipulate AF-S AF = "on", the camera does AF-S AF.

One of the first rules for time-lapse of composite work is to turn off AF.


Steve

Last edited by stevebrot; 08-27-2015 at 01:30 PM. Reason: AF-S is a red herring and not pertinent
08-25-2015, 11:34 AM   #6
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QuoteOriginally posted by stevebrot Quote
You stipulate AF-S, the camera does AF-S.

One of the first rules for time-lapse of composite work is to turn off AF.


Steve
I do not, since I use the back button to focus 😉

--> then why is AF not turned off?
08-26-2015, 05:57 PM   #7
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QuoteOriginally posted by Azergoth Quote
I do not, since I use the back button to focus ��

--> then why is AF not turned off?
Perhaps, because it is still turned on?

There is probably someone somewhere who would be just as puzzled if AF were off for composite shooting even though the AF button was clearly in the "ON" position.


Steve
08-27-2015, 01:09 AM   #8
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But that's the purpose of the AF Back Buton!!! 😜
It makes no sense: our ask to allow AF to a specific button to keep entire control and suddenly, af is "atomatically" turned on.

... And in the mode -time lapse- where automatic AF is the least useful. 😂

08-27-2015, 03:04 PM   #9
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QuoteOriginally posted by Azergoth Quote
But that's the purpose of the AF Back Buton!!! ��
The purpose of the AF button is to trigger AF separate from the shutter button half-press. Optionally, the shutter button half-press for AF may be disabled. That option is the common set-up for "back button AF".

I don't see the part of that configuration where the AF system is turned off. If you do an action to invoke the AF system and the side lever is in the "ON" position, the system will attempt focus. These actions include:
  • Pressing the AF button
  • Pressing the shutter button (unless disabled)
  • Press the button of the IR or wired remote. Note that both emulate and are strictly equivalent to the shutter button (support half press functions) and will follow the shutter button rule for AF as a result.
  • Built-in intervalometer. Drive modes leveraging this feature do NOT follow the shutter button rule, but AF mode and state (on/off) still apply. If AF is turned on, the intervalometer will attempt to invoke the AF system as part of the exposure sequence. See below for why this is a good idea.
It is that last point that you find puzzling. It might help to explain the most obvious use case for AF during interval shooting. That case is where the contents of the frame may change between exposures and where an in-focus result might be desirable. A good example might be a mobile camera set to expose at interval as it is carried through an urban environment.

The other major use case is interval shooting where you need manual or fixed focus. The common example would be time lapse of the night sky or stop-action animation.

For both cases above, it is easy enough to turn AF on/off using the switch on the side. It is not as easy to have interval shooting AF follow the shutter button rule while also providing the option of unattended AF. For your use case (AF turned "ON", interval shooting, shutter button AF disabled, AF on demand via AF button) it is harder to provide a solution that will also support both cases above. A possible work around might be an external remote (IR or wired) with intervalometer. I have two such devices on the desk next to me.

Lest, you think I am not taking you seriously, I can think of at least one cool real world example where the behavior you want would be useful. That would be the case where you want to do a focus pull between exposures using the AF system. A target at different pre-set points in conjunction with back button could be used to accomplish such with great precision without having to fiddle with the somewhat touchy manual focus on many lenses.


Steve

Last edited by stevebrot; 08-27-2015 at 03:13 PM.
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