spot metering is used when you want to meter a specific subject like in snowy conditions,center weight and ESP will be fooled into under exposure,using spot metering and meter something else will give a better overall exposure
This is the MOST basic metering system which existed for quite a long while already. You need to understand how to guage a scene and look for a mid point to meter off. Or off a person or subject which needs to be exposed accurately without referring to other parts of the scene which may give the camera inaccurate exposures in the other modes.
it can be useful; but it doesn't mean just because it's there you have to use it
it's definitely going to be useful sooner or later, but as far as i have recalled, i have used it perhaps twice while shooting; it really depends on what sort of scenes you shoot;
if you shoot landscapes, street, where most of the ambient light tends to be very consistent when it comes to fooling central weighted/evaluative metering.. and you can remember how to adjust it according based on lens/body combination.. then you don't really need spot.
I remember 15 years ago when I learn the spot metering... Shot several rolls of film in one week only by using spot metering... including experiment with sunset, portrait, and nature photographer. The result? The first roll was horrible... but it was getting better and better towards the third roll.
Is it me or have built in multi segmented metering improved so much that conditions that would trick a camera's exposure system back in flim days (say 5yrs back), is no longer applicable. The processor stored lighting condition references are much larger compared to old days.
I seem to find that spot metering is required less on my DSLR as compared to my MZ5n.
No, focus points are for lens focusing. Spot metering is a way to take exposure readings from a specific area of the scene.
Its used for :
1. Situations where the lighting conditions are tricky, and you want a specific part of the scene to be exposed correctly. (ie. so you spot meter than portion, and the camera correctly exposes for that area.)
2. Checking the exposure differences of a scene (very bright and very dark areas) and deciding what exposure to use (ie. compromise of the 2 exposures; expose for bright area; expose for dark area)
3. Creative exposure (eg. silhouette)
No. Your camera manual has chapters for metering and for focusing. They are separate topics. They can be linked (spot metering at focus point) but that's not a must. Read the manual, you'll see how your camera handles both.