It's surprising that my post of September 7 is still the most recent post here.
I have found a reason to switch on and off the highlighting of overexposed parts of the frame, in order to check for potential flare when adjusting the aperture of the condenser of my microscope. It would be great to be able to hit a key to toggle this feature.
In photographing stained slides, if I understand correctly, since the background is transparent, correct exposure is a different sort of beast. I expose the background to ask close to white as possible to do given that contrast should accomodate the mid tones in the tissues. I found that when the iris is open too much, the edge of the field (with the field iris closed enough to be visible as a circle) can display overexposure until the condenser aperture is closed down enough to eliminate this flare.
Whatever the reason, is it possible that there already is a key binding for this.
Alan Davis