..What's the difference between A and M as it would pertain to my DS and my ZX5n?
On the ZX-5n...
'F/FA' lenses: Operate in Metered Manual, Av, Tv, and P modes. Six-segment metering, center weighted, and spot metering all available, as well as TTL autoflash. Focal length and focus distance are also communicated to the camera. Not sure if MTF tables in FA lenses are used by the ZX-5n or not (the instruction manual doesn't say, so I'll assume no). AF mode is available, or focus-assist manual focus (a light goes solid when you're in focus).
'M' lenses let you operate in the following modes: Metered manual, and Aperture Priority. Metering is center-weighted. Focus-assist is available, but not AF. Lens focal length, MTF, and focus distance aren't communicated to the body.
'A' lenses: operate in Metered manual, Tv, Av, and P. Metering is six segment, center weighted, or spot. Focus assist is available. Not sure about the communication of focal length, and focus distance. MTF tables are not available.
The ZX-5n doesn't have a control for manual aperture, so if you want to use MM or Av modes, you must have a lens that offers an aperture ring. That means that if you put one of the FAJ lenses on a ZX-5n, you can only use P and Tv modes.
How K and M lenses differ is a little before my time, and I just can't say. ;)
