Originally Posted by homey
Sorry but what you're describing in NOT spot metering!
Spot metering is the ability to adjust exposure at a specific point in the frame. It has nothing to do with focus at all. Samsung tech support have confirmed that the S3 does indeed do exactly this, mine used to do it, approx 50% of the phones I tested to do it!
You choose a point where you the exposure adjusted to and that's what's supposed to happen. Any point, anywhere in the frame.
It's the same on any DSLR or any reasonably sophisticated point & shoot.
I can understand your confusion, but I have been a keen amateur photographer for around 40 years and I think you are conflating digital camera capabilities with the definition of spot metering. Spot metering is fundamentally about the size of the area of the image which is being measured to determine correct exposure, not about where in the frame that spot lies.
Firstly, advanced film cameras were also capable of spot metering and this was *always* referring to being able to limit the exposure measurement to a small area in the *centre* of the image. Secondly, spot meters are also available as stand-alone devices. These have a narrow field of view spotting scope and the exposure reading is taken from a very small and specific portion of the scene. For you to understand why this became important, and how it is best used, I suggest you read about Ansel Adam's Zone System, which enabled photographers, in pre-electronics days, to measure the reflected light from different parts of the intended image and place these in 'zones', which ranged from pure black, through specific shades of grey (because it is about light intensity, not colour), to pure white.
So, spot metering is the term used to describe measuring the reflected light from a small, specific area of a scene, using a meter with a very narrow field of view.
What you are talking about is a very particular, and necessarily modern, implementation of spot metering. This is because you are familiar with moveable focus and metering points which, yes, are available on many modern digital cameras, but which were never present on old cameras. As I say, I think you are confusing concepts with implementations.
On my Canon T90 (a very advanced, heavily electronic, film camera dating back to the 1980s), I used spot metering almost exclusively, and did it in the following manner: I would focus, then place the most obviously important part of the image in the centre of the frame, half-press the shutter button (which would measure and lock the exposure), then dial in exposure compensation to place the small, specifically measured area in the correct exposure zone, then move the camera around to check where the spot meter was placing other brighter and dimmer areas on the zone scale, then re-frame the image, and then fully press the shutter button to take the picture. And if you think that sounds like a faff, you should try using a mahogany and brass field camera with a separate hand-held meter.
I've described the way I experimented to determine how the S3's camera behaved, and I suggest you do the same. I think you'll find it instructive, and I am sure you'll then better understand the differences in the metering patterns.