In article <54i77f$ovb@news.sphere.ad.jp>, silence@iac.co.jp says...

>I just finish reading an article about depth of field and here I am
>trying the techniques documented as it is written.Fortunatly the
>photographer in the article uses the same equipment as I do (Nikon
>F4).
>
>When I read the article, it was mentionned that the photographer had
>to adjust by 1/3 values the exposure to obtain the best results for
>background and foreground separation...
>That's where I am puzzled: I rotate the aperture ring of my Nikkor AF
>lens but it doesn't hold between standard values. Same story for the
>speed dial on the camera F4 body: no in-betweens... Wait a minute! The
>exposure compensation allows me to modify my exposure settings by 1/3
>increments (so does the ASA number setting dial of course!). My
>question now is "what does the exposure compensation (or ISO dial)
>changes when I rotate its dial:the shutter speed? the aperture of the
>lens? or both depending of the mode I am (Shutter or Aperture priority
>or Program mode)? If it was the case, it would mean that both shutter
>speed and lens aperture can be increment or decrement by 1/3 values,
>isn't it? "
>
>It would be nice to know this information (which I could not find
>written anywhere by the way)...

Hmmm, DOF sure doesn't change much with 1/3rd stop changes....,
but slide exposure sure does. The aperture ring may be changed in
a continuous way (approximating 1/3rd stops is not hard - but if the
ring will not hold inbetween stop positions, it could use some
simple cleaning/adjustment [never could stand those icky Nikon AF
lens aperture rings - just one of MANY reasons for buying MF
lenses instead! ;-]). To your question: since you are merely changing
the film speed rating when you adjust the ASA and compensation rings,
it is easy to figure out what gets changed on the camera in different
modes. In Manual, either the shutter speed or aperture (the aperture,
for fractional stops); in Aperture priority auto, the shutter speed;
in Shutter priority auto, the aperture; and in Program, probably both (depending on conditions).
Hope This Helps