D800 Live View exposure simulation
This is my attempt to summarize and understand the exposure preview function in Live View, based on observations made on a D800E with the new 1.0.1/1.0.2 firmware. Please let me know if I am getting something wrong.
When in Live View mode, the function of the OK button (and other controls) will depend on the exposure mode.
In all exposure modes, toggling the OK button will show or hide the exposure compensation scale along the right edge of the monitor.
When using LV with A, S, and P exposure modes, the lens aperture remains at max (wide open). The monitor presents a simulation of the result that the Live View autoexposure system will produce for this scene. It is a simulation because the monitor image is not produced by changing aperture (or shutter speed, obviously), but by scaling the sensor output. If you toggle the OK button so that the exposure compensation scale is visible in the monitor, the simulated image will include the effect of the exposure compensation setting. When the OK button is toggled to hide the compensation scale, the compensation setting is not applied to the monitor display, but it will still be applied to your shot. Note that in A, S, and P modes, you can't change lens aperture to judge DOF on the monitor. The aperture dial and DOF preview button have no effect.
When using LV in M mode, the behavior is different. The lens aperture can be changed via the aperture control dial, so you can see its effects on exposure and DOF. But the DOF preview button does not work. The monitor presents a simulation of what it thinks your selected exposure settings will produce. The exposure compensation setting has no effect on the LV simulation, or on the exposure that will be used for your shot. Pressing the OK button just shows or hides the exposure compensation scale. The reading on that scale is the difference between your manually set exposure, and what the autoexposure system (including compensation setting) would use.
The simulated LV displays will not always accurately match your shots. Page 46 of the (English) D800/D800E User's Manual lists several conditions where the match may be wrong, including adjustments outside -3 and +3 EV, Active D-Lighting, HDR, bracketing, flash, etc.
Corrections and additional tips?
Julian Vrieslander wrote:
When using LV with A, S, and P exposure modes, the lens aperture remains at max (wide open).
Not mine... I'm on a D800, with the lastest FW, and tested using a 24-70mm f/2.8.
Note that in A, S, and P modes, you can't change lens aperture to judge DOF on the monitor. The aperture dial and DOF preview button have no effect.
Mine works differently.
[In M mode ... ] the DOF preview button does not work.
I guess it is "always on"
Pressing the OK button just shows or hides the exposure compensation scale.
Well, on mine, it shows the resulting exposure taking into account the current settings when showing, and the scale actually shows the amount of over/underexposure (as you also go on to say next:
The reading on that scale is the difference between your manually set exposure, and what the autoexposure system (including compensation setting) would use. [ ... ]
Corrections and additional tips?
Hm... it appears yours work differently than mine then. I haven't tested this very carefully in all modes as you have done, but my summary of what I have tested is:
- When in A or M mode, the aperture changes physically, independent of whether the OK button has been pressed or not.
- In S and P mode, the aperture stays whereever it is at when the exposure compensation scale is not showing, but changes physically when the scale is showing.
- When the scale is showing, A, P and S mode attempts to show the resulting shot (with the usual caveats -- but also with limitations when you reach the borders of the physical apertures). It includes effects of exposure compensation you have dialed in.
In M mode it also attempts to show the resulting shot under the existing light conditions (disregarding things like flash...), and the scale shows the amount of over/underexposure.
- When the scale is not showing, the live view tries to give you a "visible" representation of the scene, i.e. it acts as a physical viewfinder and does not take into account the current exposure settings or exposure compensation.
- The OK button toggles between an "optical viewfinder" and a "simulated pre-exposure" when the exposure compensation scale is shown.
- The aperture always changes in modes where you control the aperture directly yourself. In other modes, it only changes when you are in the "simulated pre-exposure" mode.
So... if you want to see how stopping down impacts the DOF and how the picture will be exposed under the current lighting conditions, make sure the exposure compensation scale is showing.
If you just want to use LV as an optical finder, and/or possibly use flash in the studio, make sure the exposure compesation scale is not showing.
If you want to do something else, you might also be able to do that if you are careful... for instance, if you insist on working in S mode and want to see the resulting DOF and your light is stable, you could do so too... even though I guess that is a bit unusual Or if you want to focus with LV at full aperture, ensure your (current) aperture is showing as fully open, change to S mode and activate LV... etc.
Per, thanks for the quick reply. I just re-checked some of those LV modes, and your descriptions are more correct than what I wrote, and they make more sense. I need to do a more careful study. Either I managed to get myself confused, or my camera was malfunctioning. I hope it's the former and not the latter. I can fix my thought processes better than Nikon can fix D800s.
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