OM-4T Spot metering: How I use it
Keep in mind what the in camera metering is doing. In the center weighted averaging metering, the camera will give you a reading for a brightness value for a middle gray. If you take a Spot metered value, the metered value is the correct exposure to render as a middle gray.
Lets say that we take a spot meter reading of someone's face. That spot reading will generally give correct exposure for a portrait. What if we take a spot reading of a white object. In this case, the suggested reading will try to render the "white" value as a middle gray, and the shot turns out underexposed. Pressing the "Hi. Light" button shifts the metered value to give two more stops exposure and the white object is rendered correctly as a white.
Here's another example: We take a spot meter reading of a very dark object. The spot reading is the suggested exposure to render the dark object as a middle gray. The camera doesn't really know the difference between light colored objects and dark colored objects, it is just reading the amount of reflected light. So for our spot metered reading of the dark object, we can press the "Shadow" button and the spot metered reading is shifted to give 2 2/3 less exposure and the dark object is render correctly on the film.
I just looked at the manual. There is no reference to use the "Hi. Light" and "Shadow" features at the same time. Just use one or the other. What I generally do is to set the camera to manual exposure mode so that I have to set the aperture and shutter speed. I take a spot reading of a light colored object and then I take a spot reading of a dark object. Both readings show up as dots in the viewfinder, but the suggested "average" value is also shown. This is all the information needed to decide on an exposure. It is a little like having a miniature Zone System in the view finder.
