The engineers who designed all of those metering modes would disagree that the others are simple measurements.

1. Spot selects a single (maybe movable) spot to weight at 100% while ignoring all of the others.
2. Center weighted gives more weight to the center of the image than the edges and corners.
3. Full average gives equal weight to the entire field of view (or is it to each of the separate spot senors).

Separate hand-held meters (even spot meters) are simpler but they don't take the field of view into account. But thats not what we are discussing here.

Before proceeding, I want to declare openly that I am about to ask a question which some may interpret as unnecessarily raising controversy or attempting to troll the group or provoke some of its members. Please be assured that is absolutely not my intent, and it is my hope that we can have something resembling an intelligent discussion around the topic. There are some specific elements involved, and I don't want to shy away from those. But please do not interpret them as provocation.

The thoughts behind this discussion arose as I was getting ready to do the latest firmware update for my D850. It was released in April, but I somehow missed it until yesterday. It apparently provides for improved operation with certain lenses. And no...it does not add the "Eye Focus" capability that many have been anxiously awaiting.

So the question is this...and I haven't been able to find a delicate way to ask it...for those who treasure "Manual" photography, exactly what are the boundaries of thta method of operation? And for the purposes of this discussion, let's please set aside the question of whether "Auto ISO" is or is not part of "manual exposure." It's been discussed thoroughly elsewhere without resolution. I'm passionate around my position on that subject and realize that others are equally passionate around their own, different, position.

BUT...it seems that many (and I mean many everywhere, not just here) who would never consider following anything other than manual exposure management would also never consider anything other than automatic camera focus. And preferably automatic camera focus that can identify, lock in on, and focus on the eye of their subject, whether human or animal. Why is the manual choice preferred in the one case, but the automatic choice is lusted after in the other case?

Now just for full disclosure here. I proudly use autofocus essentially all the time, except for night sky photography and a few other cases where autofocus falls short. I was initially quite concerned when some of my newest cameras no longer had an autofocus assist light. (Trust me...I learned that it's OK.) Because of some vision problems relating either from glaucoma or occupational exposure to intense light (my doctor and I don't agree on which), I shamelessly depend on autofocus. And yes, I use Program exposure mode a lot of the time also. It's just too good and too convenient if I select the correct metering pattern, and I am pretty shameless about that also.

Why do we think there is such a disparity in the acceptance of automatic exposure vs. autofocus, especially since various forms of automatic exposure have been around longer than autofocus? I am really interested in the responses here, especially if we can keep the discussion civil and thoughtful.

The camera's meter does not provide a technically correct exposure. It provides an opinion based on an algorithm.

There is no single correct exposure.

If we are working with the raw file or a negative in a scene where the dynamic range is not wide we can probably achieve the same final result from two images taken one or more stops apart. With a JPEG or slide film the range is narrower.

Having captured an image at a specific exposure we may decide later to make it darker or lighter for reasons that have no technical aspects.

There are judgement calls the camera cannot make.

This is the most recent photo I have taken. My wife said grab a snap of the last glad in the garden (end of summer). I took the photo with my Fuji XT-2. I used a non-Fuji lens and so I set the camera to Aperture Priority mode. I set the f/stop on the lens and the camera selected the shutter speed.

My exposure differs from what the camera would have selected for the JPEG by +1.3 stops (you can check the EXIF data in the photo). I used the EC function in the camera to set that variance. I knew to do that because I have tested my hardware and my exposure goal is to fully utilize the sensor in my camera. The raw file I saved does that. Obviously the camera would have exposed less.

Joe