Experiments with Nikon D600 exposure - seems too aggressive

Started Sep 21, 2012 | Discussions thread
Mako2011
Mako2011 Forum Pro • Posts: 23,531
Re: Classic Mistake

creaDVty wrote:

It looks like you made a classic mistake. You used matrix metering combined with AF-Area mode "auto" and that doesn't account for focus point biases of the scene. I suggest you go back and focus on the zone five area of each scene using AF-Area mode "single" and see what you get.

Thanks for the suggestion I'll try that.

I was not aware that with AF-Area on Auto, the exposure algorithm ignores the autofocus point. I thought it always takes the autofocus point into account regardless of which AF mode was used to select the AF point.

It does....that's the problem. I was saying that your test can't account for the AF point bias of AF-Area mode "auto" as it may even choose multiple points to bias. It's simply to dynamic and inconsistent scene to scene to base overall exposure comparisons on.

Anyway, in this case, iirc, the af points chose to focus on the yellow Ferrari logo on the side of the car.

In that case the AF-Sensor FOV would cover an area far larger than the logo and hence bias towards Zone 3/4 of the black around it and lead to highlight being clipped. It did exactly what I would expect in that case. You really need meter a consistant target (preferably a mid-tone) to determine exposure tendencies.

One question about your suggestion. What if my intended subject is not zone V, like the black Ferrari in this case? Do I focus on the zone V object, use AEL, then refocus on the black Ferrari? TIA.

That would get you close and be more consistent. There will always be some dynamics in trying to measure what Matrix is doing. Remember it is looking at the entire scene and biasing towards the focus point. To get a "tendency" regards what matrix meter will do in different scenarios...I would simply look for different scenes with similar DR and a Large central mid-tone (zone 5) target. Shoot a good sample of those with matrix then spot (on same target) and compare. That might be a very relevant comparison. Your task is not an easy one but plenty of opportunity to learn by all. Good Luck

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