D780 AF problem for dogs with black faces

Started 7 months ago | Discussions thread
PHXAZCRAIG
PHXAZCRAIG Forum Pro • Posts: 18,488
Pretty much the same problem caused me to adopt BBF
1

Years ago I was trying to shoot my sister, her husband and their three new puppies.  One of them was all black.   This was with a D300 and SB-800.

Problem was obvious.  The puppies were squirmy at best, and getting them to look at the camera was an exercise in itself.   Then when the perfect moment arrived and I pressed the shutter release .... the camera wouldn't fire, and instead would try refocusing.

The problem was obvious.  The camera couldn't determine if the dog was in focus at the moment of exposure.  I had the camera in Aperture priority mode with AF-S, single point focus and autofocus initiated with a half-push of the shutter release.

To solve this I changed both focus and flash modes.   The focus mode became the mode I adopted ever since, like many many others.   Back Button Focus (BBF).   In this mode YOU determine the focus, and when you press the shutter release button, the camera will take a picture, whether in focus or not.   The focus gets removed from the shutter release.  You must use the little AF button on the back of the camera with your thumb.

Besides moving the focus to only the AF-on button (AF menu option), you must change the camera to release mode (or focus+release mode) from focus mode.  Otherwise the camera will always monitor the active focus point(s) and not fire if it doesn't detect focus under the point(s).

So the new procedure was:  prefocus on a dog, then wait for the precise moment and take the shot.   If the dog did not move too much from the initial focus point, it will be in focus.

There are other advantages to the BBF method as well, and they are well-documented on the Internet.   You can follow-focus moving subjects simply using your thumb (and AF-C).  Remove thumb when focus achieved, or continuously focus while shooting.

But that was half the problem.  The other half was getting proper flash exposure when shooting a black pupply in the middle of two people and two other (white) dogs.   The camera was originally basing exposure on the area under the focus point, and the subjects were getting over-exposed.

Seeing how back then I was really just learning and using the camera in mostly default modes, I was trying to use TTL flash.   There is a big problem with TTL flash and shooting animals (and small children too).   Animals (and some small children) have very fast reactions and will visibly react to the preflash that is required for TTL.   The result in animals is often closed or nearly-closed eyelids.   Children too, and some adults will also 'half-blink' looking sleepy or drunk.

So I discovered the use of the Fv Lock function.  With that function, you pre-measure the flash output and set the flash power with a test shot, and then when you take the intended shot it uses that flash power setting.   Look this one up if it sounds like something you want to use.

Alternatively, and this is the method I've used for the last 15 years, just shoot in manual flash mode.   Especially when using strobes in a studio setting, there is simply no need for TTL.   Set up the strobes, backdrops and props you need, perhaps with subjects or test subjects.   Dial in the strobe power manually until the histogram and results look good, and then leave the strobes alone.    Only change if you change apertures or shutter speeds.   It's just plain simpler than Fv lock, which is sort of pushing TTL into manual mode.

Once I had the camera set, it was simply a matter of waiting for the right moment and pressing the shutter release.

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Phoenix Arizona Craig
www.cjcphoto.net
"I miss the days when I was nostalgic."

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