SpOOkY: Yes, 24mm on ANY lens will be the same on the A200.

Likewise 24mm on ANY lens will be the same on the A900. If it is an APS-C lens though it may have dark corners.

24mm on APS-C or 36mm on FF is okay but when you want to take social events with people and crowds, it will not be wide enough.

Oh, and you should not recompose:
http://www.mhohner.de/recompose.php

If possible, use Local AF mode. Also, after AF lock, it does not lock exposure. You will need to press the AEL button for this.

You will want to press the AEL button on a face to get a spot meter reading off it, then set your focus point on the face, and shoot.

Sony, like Minolta, lock AF and AE separately. I see great flexibility in this compared to other systems which lock both AE and AF. But if you have an A100/A700/A900, pressing the DOF Preview button ALSO locks AE/AF.

To focus on objects OUTSIDE of the area, pick the closest AF point instead of using the center AF point and recomposing - the misfocus will be greater than if you used an outer AF point.

Also, to focus on groups, I usually focus on the person CLOSEST to me. It ends up looking a lot more pleasant than focusing on the rear row. Try both. To be safe, you can focus on the second row from front (mmm mmm), 1/3rds into the crowd.

This can be used for long tables also. But I really always try to shoot them at an angle which is easier to get them all in focus.

Finally, when passing it to friends, Wide AF is the way to go. Too often, I get backfocused pictures because my friends shoot an even number of friends, so the center AF point is on the background!

cjlai: I prefer the reverse front ring method - you can zoom the lens that is on the camera, and have full autoexposure, AF and aperture control. The reversed lens is just functioning as a magnifier, an expensive version of the Raynox!