D810 depth of field preview button!

[Gigas]

When I use the D810 depth of field preview button it gets darker on live view than without the button pressed! The button is for helping to set focus right when the iris is fully open but the LCD gets darker than without  using the PV button! Wye is that?

[David H. Hartman]

Gigas,

My D800 doesn't seem to offer "DoF" preview during still Photography live view. I was trying to replicate what you describe but I'm not able to.

Maybe a D810 owner will comment soon.

Dave

[Les Olson]

You would expect the image to darken when you activate DoF preview because the diaphragm has shut down to the taking aperture.  However, not all Nikon dSLRs respect DoF preview while in live view.  Evidently the D810 is one that does. 

My D500 activates DoF preview in live view, but the darkening of the live view image is very slight - much less than when you look through the viewfinder.  I presume that is because - according to Thom Hogan - the live view image uses "a form of temporary Automatic ISO" to keep the live view image bright.  Maybe the D810 does not make that compensation as efficiently.

[Gigas]

Yes, that could be the case! Most of my macro shots are in f18-20 so it is not easy to nail the focus unless the aperture opens up fully!

[Matthew Currie]

I gather from a post elsewhere that this issue is arising with a manual focus lens.  It's not made clear also whether the camera is in Manual mode, but if I read information elsewhere right, I think the D810 behaves differently when in manual mode, and may not do the same exposure compensation in LV as it does in other modes.   There is, apparently, a toggle of "exposure preview" done with the OK button.  Could that have an effect here? 

I'm basing this only on what I read, as Nikon seems unable to settle on how to handle DOF preview, and unable to write coherent instructions for whatever they decide.  On the D7100, the DOF button has no effect at all in Live View, and the automatic aperture of a manual lens is also disabled.  One therefore gets, from manual lenses only, a true DOF preview by adjusting the aperture.  The exposure compensation of the view screen tries, with poor consistency, to keep up, rather than darkening consistently.  The D3200 behaves much the same, except it has no DOF preview button.  The behavior for manual lenses is the same, and for AF lenses, whatever aperture is set before entering LV passes over, so one can get a kind of "poor man's DOF preview" by switching in and out of LV at different apertures, but no DOF preview in the viewfinder.  The same procedure is the only way to get a preview in Live View on the D7100.

In order for preselected apertures to carry over from viewfinder to LV, one can imagine that disabling the mechanical auto aperture would make sense, but nowhere in the manuals is it mentioned, nor is the absence of DOF preview mentioned in the D7100 manual anywhere I can see. 

[arthurking83]

Gigas,

My D800 doesn't seem to offer "DoF" preview during still Photography live view. I was trying to replicate what you describe but I'm not able to.

Maybe a D810 owner will comment soon.

Dave

D800 will change the aperture value in real time in photography live view mode .. so no real need to 'stop down' using the DOFP button ..
ie. if you set the lens to f/16 in Lv mode, it be set to f/16 in Lv mode therefore DOF P mode all the time.
If you start the lens at one aperture value and change value(s) you should hear the slight clicking of the lens either opening up or closing down as it changes from stop to stop too.
For a CPU/CPU'd lens, you change the aperture as per normally using the sub command dial.
For manual lenses you change aperture using the aperture ring.

If you don't see brightness changes(in Manual mode), then you may have the Lv mode to automatically compensate the screen to maintain brightness levels or AutoISO enabled pr something.
In Lv mode press the OK button to enable auto screen brightness mode or not. You should see the brightness indicator on the RHS of the review screen when in manual brightness mode in Lv mode.
With OK pressed again and the Ev indicator not on screen .. the Lv review screen will 'try' to maintain a level brightness regardless of expected Ev value in the image.

In one of the semi auto programs mode(eg. Aperture priority mode) the camera will compensate shutter speed as you stop down and the Lv review screen will try to remain as bright as it can.

(at least the E model does this, and I assume it'll be the same with the std D800 too)

But in answer to the original statement .. yes it does .. basically all the time, and in real time.
Hope that helps.

[David H. Hartman]

arthurking83,

I'll be damned: I forgot. With camera in hand I stopped down the lens and I can hear the aperture closing down. In low light the viewfinder get dim as auto ISO is set to 100-800 at this time and camera would need a higher ISO to avoid under exposure.

Thank you for the correction,

Dave

[arthurking83]

.... In low light the viewfinder get dim as auto ISO is set to 100-800 at this time and camera would need a higher ISO to avoid under exposure.

Thank you for the correction,

Dave

Also remember the OK button for review screen brightness.
Personally I don't like this auto brightness feature as it displays a misrepresentation of the actual brightness of the final image.
But in some situations it can help tho.