Sony Alpha 100 WB not matching "As Shot" in ACR 3.7

Question

I have heard that for some cameras, the values don't match up perfectly, but isn't ACR supposed to read the WB from the out of camera raw file and display it as that? For example, if I manually set the WB in camera to 5200K G0, when I open the file in ACR, it displays (and adjusts) to something other than that under the "as shot" preset. While it's not off by a lot, maybe a max of +/- 300K and +/- 11 for the tint, it's still a problem when I want to batch process. It does vary with shots of almost identical composition.
Another question that I have is how can I have a default setting of 0 for the exposure slider, ect, without having ACR adjust the OOC shot to those settings? For example, lets say I have a shot that was properly exposed when I shot it. If I have the default exposure setting at 0 in ACR, when I open it (or display it in bridge) it lowers or raises the exposure to 0. Shouldn't it make the exposure value from the camera 0 (x=0 exposure) for that shot?

Answer 1

Michael,
Your assumption about WB differences assumes there is something sacrosanct about what the Sony engineers put into the WB algo in your camera. There really isn't. The finer distinctions are going to rely on your eye in the end with virtually any camera and editing application. Allow me to approach the matter from a broader perspective.
Light temperatures are never a constant, even in full Sun--lots of variables, and that is why many cameras, and all image editors (worth using) have approximations (like Sun, Cloudy,and various artificial light sources, etc)that you can choose--as well as auto. Those are at best only close approximations of the conditions of any shot--except maybe in a controlled lighting context in a studio where you have calibrated everything (and rpeated it about every two weeks). It is an engineering design. That is why 'Nikon' color and 'Canon Color' and 'Sony Color' differ.
If you want even closer tolerances, carry a Gray card, and use it liberally when you sense a lighting change or shift from sun to shade, for example. That will just be a better approximation (providing that the angle of the card to the light source(s)doesn't throw that off :)
The best advice, IMO, is to learn to rely on the feedback between your 'eye' and the image before you in the editor--and the objective there ought not to be simply trying to remember the lighting you saw when you shot--really subjective, and impossible--but to produce that lighting that you consider most effective with respect to the whole image before you on the screen--and that is a lot of parameters besides WB. Let's call it 'Michael's Color.
Getting the best photographically out of an image is subjective and requires balancing the effects of the many adjustments available in whatever application you are using. It is easy to forget that a photographic image is just a media analogue of the real world, not a replication of it, designed by you --or left to the Sony and Adobe engineers' default 'auto' senses of how it ought to be.