Nikon F100 compose and frame - focus problem

nsouto · Jul 22, 2013

Hard to split the last microsecond but going from practical use, slow to fast:
F4<D80<F100<D200<F6

L Gebhardt · Jul 22, 2013

tkamiya said:
Thank you very much for trying it out. On mine, both 9 and 10 are set to zero as well. I cannot always reproduce my problem but when it does, it's pretty consistent. It may be scene dependent that camera fails to confuse camera movement and subject movement. With single servo mode, and with [ ] showing, it tries to refocus when I recompose.

I guess Nikon firmware wasn't as advanced as ones it uses today.

Again, thank you very much for trying it out with yours.

Since the camera was on my desk I started using it again. I put it back to what I thought was my normal mode and found it wouldn't release if I recomposed and the AF point wasn't in focus. Turns out I needed to put it back on Continuous when CSM 4 is turned on. Never noticed that before, but I rarely change settings once it's working well.

I did a little digging on this odd behavior and it seems that it's a feature called Trap Focus (maybe not an intentional feature, but people treat it as such).

I tried a bunch of settings while messing around with the thing and couldn't reproduce the behavior you are seeing. What happens in Continuous mode; does the behavior change at all?

L Gebhardt · Jul 22, 2013

From the manual on page 36

Set focus mode selector to S or C for autofocus operation.• Set focus mode selector to S (Single Servo AF with Focus-Priority) or C
(Continuous Servo AF with Release-Priority). Camera continues to focus
automatically on the subject when the shutter release button is lightly pressed.
S: Single Servo AF with Focus-Priority
The shutter can only be released when in focus indicator / appears in the
viewfinder (Focus-Priority). Once focused on a subject, keeping the shutter
release button lightly pressed locks focus (Focus Lock). With a subject that
has been moving, the camera continuously focuses on a subject as long as
the shutter release button is kept lightly pressed (Focus Tracking, page 68)
and focus locks when the subject stops moving.
C: Continuous Servo AF with Release-Priority
Since the priority is on shutter release, you can release the shutter
regardless of the focus status (Release-Priority). Focus is not locked when
/ appears in the viewfinder and the camera continues to focus on a
subject until shutter release. With a moving subject, the camera
continuously focuses on a subject as long as the shutter release button is
kept lightly pressed (Focus Tracking, page 68).

Then on 68

Focus TrackingWhen the focus mode selector is set to Single Servo AF (S) or Continuous Servo
AF (C) and the shutter release button is lightly pressed or AF Start button is kept
pressed, the camera automatically switches to Focus Tracking when a moving
subject is detected. Focus Tracking enables the camera to analyze the speed of
the moving subject according to the focus data detected, and to obtain correct
focus by anticipating the subject’s position—and driving the lens to that
position—at the exact moment of exposure.
In Single Servo AF, Focus Tracking is activated with a subject that has been
moving in advance to the focus detection, and focus is locked when the subject
stops moving and / appears in the viewfinder. In Continuous Servo AF, camera
continues to track subject (even with a subject which started moving in the
middle of the focus detection) and focus is not locked.

So what's biting me is the Focus Priority feature. It sounds like your issue is with the Focus Tracking. Looks like these are both unable to be adjusted like they can be on the newer DSLRs.

mweintraub · Jul 22, 2013

MartinCrabtree said:
It seems the F5 is faster than the D90 but neither is slow.

I havn't played with the D3 or D4, but the F5 with a 50mm 1.8D is the fastest I've seen.

tkamiya · Jul 22, 2013

Hey, guys.... if you want to talk about focus speed, will you please create your own thread?
Thanks.

tkamiya · Jul 22, 2013

Larry,

In continuous focus mode, it works as I expect. It continuously focuses and does so correctly. My problem does not happen for every subject but for certain subject and perhaps situations, it happens consistently. (very annoying) I am not able to recreate it on demand.

I am familiar with the statement made on page 68 of the manual. I am thinking, even though the subject is not moving, maybe camera thinks it is moving.... and in conjunction with the fact I AM moving the camera, it gets confused. I am not sure if there is a motion censor involved in later bodies to prevent this behavior in case of re-composition moves. It would be very nice if I can disable this.

One situation I noticed is that say I am taking a portrait of a person. Focus on the eye, press down half way and recompose so that the focus point is not on the face. It refocuses.

L Gebhardt · Jul 22, 2013

tkamiya said:
Larry,

In continuous focus mode, it works as I expect. It continuously focuses and does so correctly. My problem does not happen for every subject but for certain subject and perhaps situations, it happens consistently. (very annoying) I am not able to recreate it on demand.

I am familiar with the statement made on page 68 of the manual. I am thinking, even though the subject is not moving, maybe camera thinks it is moving.... and in conjunction with the fact I AM moving the camera, it gets confused. I am not sure if there is a motion censor involved in later bodies to prevent this behavior in case of re-composition moves. It would be very nice if I can disable this.

One situation I noticed is that say I am taking a portrait of a person. Focus on the eye, press down half way and recompose so that the focus point is not on the face. It refocuses.

I'm almost certain there is no motion sensor in the camera. I think its definition of moving is based on the information in the 10 segment matrix meter (so it can't detect subject vs camera movement). I'm not sure if it detects color or not. I know the later cameras, (F5 and pro level DSLRs) will follow subjects based on color detected by the RGB sensor in the metering system. So I'm reasonably certain the camera thinks your subject is moving when you recompose and turns on the Focus Tracking. I get the impression Nikon expects you to push the AF/AE Lock button when you focus and then do the recompose. A very kludgy system in my mind. I wonder if the F6 is any better.

Portraits were why I went to using CSM 4. I don't recall having your issue with the camera, but I know the AF drove me crazy until I removed it from the shutter button.

markbarendt · Jul 22, 2013

tkamiya said:
One situation I noticed is that say I am taking a portrait of a person. Focus on the eye, press down half way and recompose so that the focus point is not on the face. It refocuses.

Have you tried back button focus?

After finding CSM 4 and getting used to it, it is now pretty frustrating to shoot without this feature.

tkamiya · Jul 23, 2013

I tried in the past but I could never get used to it....

epig · Jul 25, 2013

I've come across a few AF bodies (Canon and Nikon) where the shutter release is overly sensitive and if I lift the pressure from my trigger finger even slightly esp. when recomposing, the camera refocuses. If I press harder to avoid this, I inadvertently fire the shutter.

Eric

ic-racer · Jul 25, 2013

I have noticed a similar glitch (or feature?)with the Nikon N75. Most of the time pressing the shutter button part way freezes the focus so you can then compose. However, if you fix the focus on a fence at an angle, then move the camera it does a very annoying 'follow focus.' I don't see any way to turn this off in the manual.

Nikon Collector · Jul 29, 2013

summicron1 said:
ya know, the instruction manual for my Leica CL doesn't contain even one single sentence that is 1/10th as confusing as this one. Custom Function 9??? Dynamic AF mode with closest subject priority? Single Servo mode?

Cripes.

We're trying to take pictures here, folks, not launch the Space Shuttle.

Focus, match needle, shoot. End of story.

<Rant mode><exit>

LMAO

Nikon F100 compose and frame - focus problem

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