Shooting moving subject (walking) at f/1.8 - poor hit rate in indoor light

I shoot catwalk regularly and unfortunately not always under ideal light conditions

Coming from a D3, I did have major problems initially too getting an acceptable rate of in focus shots with the D800, despite having much experience with shooting catwalk (with lenses like a.o. the 2/200VR, 200-400VR and lately 2.8/70-200 VRII, fully open or only slightly stopped down on bodies like the D1H, D2X)

To start with, my 'standard' settings are AF-C, with 51 AF points, and AF on the shutter release button, while using one AF point (usually the most right sided one as I most of the time shoot vertivally, in portrait mode), with the winder attached, with standard AF tracking. No 3D, no AF-S

At first i did not see a major improvement even after having returned the D800 to Nikon to check and if necessary recalibrate the AF

After some time though I started to notice that the AF of the D800, although more accurate and sensitive then that of the D3, was actually less snappy, causing OOF shots (especially the first shots when shooting single shots and small series) when only being triggered through the release button o the camera, due to what I think was the longer time it took to get things in focus when starting 'cold'

As a solution I decided to fall back on the technique I used when shooting surf with my D3, with a 4/600 AF-I and TC14

I keep the AF standard on the release button of the body or winder (when shooting vertically), but while framing I already, before taking the shot, activate the AF constantly with the AF-ON button on the back of the camera (or the grip) as well

Works out fine for me now, with a 95+ percent rate of in focus shots even under the worst kind of light

Latest show I shot

http://www.pbase.com/paul_k/20121124_mafb_adam

was in a venue where despite the length of the venue only the area nearest by (in front of the jurors table at the head of the catwalk) was lit, and the rest was only dimly illuminated by the spots on paintings on the wall, and stray daylight coming from the front entrance, and from high windows in the back

As said, the illumination level was very low and consequently pretty awfull for AF, but the D800 managed excellently. As far as exposure was concerned, I saved my day thanks to the 2 SB800 I had on light stands and operated with Pocket Wizard TT5's with which I improvised a rudimentary stage light like light set up especially for the models further away down the catwalk

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all in a day's work
http://www.pbase.com/paul_k/