If you look at the circuits from the patents, the auto exposure is just
light hitting the film, reflecting onto the silicon sensor whose output
is integrated and compared to a trip value. The second curtain is
released when the integrated light sensor value reaches a certain
point, the trip value, determined by the aperture and ASA compensation
dial. This is similar to the OM2 auto exposure. The OM-4t circuits can
also digitize the exposure value just integrated to calculate a stored
exposure value with the memo function. The memo function is a digitized
value from the auto exposure (or spot meter reading). The quantization
from memo or spot mode will result in non-continuos exposure values,
but they are not fixed steps.
The cool thing about the OM-4t that many cameras miss, is that if you
change the aperture or compensation for with a stored value, either
memo or spot, the camera will adjust the shutter speed to compensate.
You cannot do that on many cameras that have AEL. The Contax G2 for
instance. This is just one more of those intuitive things Olympus seems
to understand. Hopefully they will not forget their past with the
advance of new technology.
Wayne
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|