I made an example to show you my problem and I hope it highlights successfully what my problems are
I am at matrix metering at f/2.8 iso 800 (that is typical for indoor). AUTO ISO is off. Shutter speed is around 1/8 that allows enough light to register. According to ambient light meter I am at +0 which is what I am going for.
FWIW, Exif says ISO 1600 in the first one.
Lets see the shot now, that is a typical shot with ambient light. Some light is coming from the living room bulbs and thus the orange color and some color behind the bed giving that blue hue at the back
I assume Incandescent white balance, or Auto WB giving similar, so the blue background is window light, Daylight light, wrong for Incandescent WB. Mixing light sources is generally impossible, WB can only correct for one of them. Any try at a "compromise" WB will simply be wrong for both then.
now I plug the sb-700. And I see the image TTL BL. I dial in camera FEC -2 (I also tried with FEC 0 at camera at -2FEC At the flash body). Both settings give the below shot.
I tried with an sb-500 as well with FEC -2 and I got exactly the same shot
FEC in camera and in flash body simply add to a total, so these two are the same thing, they add to the same total. And camera EC also adds to it, unless overridden in D750 menu E4.
Now to me this is not a FEC -2 but closer to FEC 0. Unfortunately I do not know thow to share the histograms of those two shots here.
For me FEC -2 is fire that much flash to lift shadows from the black point closer to the mid tones.
What I get is closer to what I think FEC 0 should be. The shadows are lifter over midtones. This flash shot above has blinking highlights as well.
Where I am wrong with that then?
Regards
Alex
The camera meter we see (indicating 0 EV now) is only reading the ambient exposure. It is not affected by flash. Flash has not fired yet, and flash has its own invisible metering system anyway. But flash will contribute to total exposure.
It does seem a bit bright, but you are fully exposing the ambient with ISO 1600 and 1/8 second and f/2.5. Any additional exposure from flash adds to add to be more than that existing full ambient exposure. -2 EV flash compensation will add and lift fully exposed ambient by 25%, which is 1/3 stop overexposure of the near foreground affected by flash (flash percentage calculator at
Flash pictures are Double Exposures- Outdoors ).
Remember that you are affected by Nikons TTL BL automation. If the scene is brightly and fully illuminated (as here, with your ISO 1600 and 1/8 second and f/2.5), then it automatically provides less flash fill, trying to minimize overexposure by adding flash. Automation interferes with your own efforts, automation knows what it is trying to do, and it can sometimes tend to ignore you.
Saying, in this TTL BL case, I really doubt you will see any difference between -2 EV flash compensation, and 0 EV flash compensation. Automation has its own goals. I am agreeing with you, but you may not like my reasons.
The default TTL BL mode really expects to do its own automatic flash compensation. Your events will be much more controllable if you use manual flash mode, and then do what you see you need to do to get the results you want.
But automation will generally give automated results, the opposite of user control.
But if you set ISO 100 and 1/200 second and say f/5.6, the ambient would be dark, black even, and the flash would try harder. Your -2 EV would hold it back however, it would not be fully exposed by flash then. That should show a strong difference between -2 EV and 0 EV flash compensation.
Or you could set some exposure compromise, to handle ambient and flash individually as you wish them to be.
Or, switching to TTL mode (as opposed to default TTL BL mode) will be different, no system compensation automation trying for its own goals.
Your words suggest you expect TTL mode, but the Nikon flash metering default is TTL BL instead. Balanced flash, in its own way.
Spot metering will make that switch, TTL flash mode overrides TTL BL mode, but then you get Spot metering for the ambient, which introduces other issues, perhaps unexpected. Spot metering is not a point&shoot effort, instead we must understand how to use it. But if you can get the ambient exposure as you want it, then TTL mode will respond properly to flash compensation.
I like to use an older Nikon SB-800 flash, which has its own menu to force TTL or TTL BL mode. I think Nikon should provide that menu in the camera, but they don't. They only provide Spot metering, which is NOT for beginners, and unfortunately, also does Spot metering for the ambient (but the flash is Never Spot metering).
Spot metering generally works great with flash indoors, which causes no effect when we ignore the insignificant ambient. But if fully metering the ambient, then spot metering is spot metering, for ambient.
You and I have different goals. My goal is to suppress ambient in flash pictures, which makes it easy. Your goal is to fully support the ambient, much more complicated. But I think you would like manual flash mode to do that, so you can control it.