AF question for the experts

Joined
Sep 6, 2008
Messages
350
Location
Philadelphia suburbs, Pennsylvania
I use the following settings on my D700(and D300, actually):

-spot metering
-single center point AF
-continuous high shooting 8FPS with the vertical grip
-AF-S

Despite the advanced autofocus features of these cameras, I've always preferred center weighted focussing and recomposing for composition. I like it that way and am not really looking for recommendations on other AF point options, please.

My problem is that when I focus on a stationary subject, hold focus and recompose my photo and then hold down and fire several continuous frames the camera often loses focus in the middle of the burst(mostly after the first frame, sometimes after the second or third).

I don't release the shutter at all during the burst - shouldn't the burst hold the focus point throughout?
 
Joined
May 15, 2005
Messages
1,827
Location
Israel
Real Name
Heiko
I'm not exactly sure how you hold the focus point. I do it the following way and I don't think there's much of a chance for refocussing:

1. Set the Shutter to Shutter only (no focus action)
2. Set the AF-ON button to do the focus.
3. AF-C
4. Center focus point
5. AEL to lock the exposure (toggle ON/OFF)

I use the thumb on the AF-ON button to focus on the center sensor, then release the thumb. Exposure is taken by the Shutter release, which I can lock pressing the AEL button once (it's set to be a ON/OFF toggle). I then reframe and shoot without touching the AF button.

I use mostly Matrix metering so I'm not sure if the AEL button holds the exposure over several shots, but in continuous mode you don't release the shutter to take a burst, so the exposure shouldn't change.

By removing the focus action from the shutter release, I can have both AF-S action and AF-C in the same AF-C mode, simply by using/removing the thumb from the AF button. When I keep the AF button pressed and move the center sensor to another position / object the camera will refocus, the same happens when the object under the sensor moves.

There are also several settings in the custom menu that control how focusing works and it might be an idea to look into that.

I hope this made sense to you.

Good luck.
 
Joined
Jul 28, 2009
Messages
57
Location
Kahlifornia
I'm not exactly sure how you hold the focus point. I do it the following way and I don't think there's much of a chance for refocussing:

1. Set the Shutter to Shutter only (no focus action)
2. Set the AF-ON button to do the focus.
3. AF-C
4. Center focus point
5. AEL to lock the exposure (toggle ON/OFF)

I use the thumb on the AF-ON button to focus on the center sensor, then release the thumb. Exposure is taken by the Shutter release, which I can lock pressing the AEL button once (it's set to be a ON/OFF toggle). I then reframe and shoot without touching the AF button.

I use mostly Matrix metering so I'm not sure if the AEL button holds the exposure over several shots, but in continuous mode you don't release the shutter to take a burst, so the exposure shouldn't change.

By removing the focus action from the shutter release, I can have both AF-S action and AF-C in the same AF-C mode, simply by using/removing the thumb from the AF button. When I keep the AF button pressed and move the center sensor to another position / object the camera will refocus, the same happens when the object under the sensor moves.

There are also several settings in the custom menu that control how focusing works and it might be an idea to look into that.

I hope this made sense to you.

Good luck.

Nice explanation...It helped me a lot.......Thanks.:cool:
 
Joined
Sep 6, 2008
Messages
350
Location
Philadelphia suburbs, Pennsylvania
  • Thread Starter Thread Starter
  • #4
I've heard a lot of people swear that once you use the AF-ON button that you'll never go back. I'm going to do some more experimenting to see if I can get things how I'd like them with shutter release AF, but thanks for the suggestion and explanation.
 
Joined
May 15, 2005
Messages
1,827
Location
Israel
Real Name
Heiko
I've heard a lot of people swear that once you use the AF-ON button that you'll never go back. I'm going to do some more experimenting to see if I can get things how I'd like them with shutter release AF, but thanks for the suggestion and explanation.
I started to use the method I described above around 18 months ago. I got used to it pretty fast and now I can't figure out how to use shutter focus. But each method has its conveniences.

The way you describe the problem it looks like the camera acquires focus again once it took a picture. I haven't tried it, but I will when I find some time.

Regards,
 

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