Another strange bug with D4, possibly D800!?!?

I can reproduce your problem with the D800 but not the D4.  My D4 has the latest firmware that was released last week.  1.04?  I tried this morning moving from indoor light to outdoor light through a window.  With AF lock held the indicated exposure changes as I swing the camera from indoor to outdoor light.  When I let go of the lock button the indicated exposure stays steady and it is the correct exposure.

On the D800 I can't set the AF-ON button, but I can assign the AE/AF lock button to be AF Lock Only.  So I did that and repeated the test.  Indoors I focused on something.  Indicated exposure was f/4 at 1/15s. I pressed and held the assigned AF Lock button and swung the camera outdoors.  The exposure changed to f/4 at 1/60s.  But this is way overexposed if I trip the shutter now.  If I release the AF lock button (holding the AF point steady over the same target the exposure jumps to something like f/4 at 1/400s.  This is the correct exposure.

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Mike Dawson