Steve Cottrell wrote:
On 24/1/17, Eric Weir, discombobulated, unleashed:
I've been puzzled by this. How does it work? There are only three
variables--sensitivity, aperture, shutter speed. Doesn't it have to
adjust one of those? Then what's with a separate function?
If you use your camera on fully manual settings (ISO, iris, shutter
speed) then exposure compensation is not relevant.
If you are using an automatic setting (eg program, aperture value,
shutter value) then the suggested exposure by the camera may not appeal
to you. Hence you can adjust the camera's 'thought' on what it thinks is
the right exposure for your scene.
Think of sitting on a bus. You paid your ticket and chose your seat,
you've paid for your bag and all is good. It should be a perfect trip.
But you decide that the driver is going too fast for your liking - he
has a dial on his back that you can turn either way to make him slow
down - or go faster!
Of course, there may be any number of reasons why the camera's own
thoughts on the exposure in hand isn't right. With me, it's usually
because a scene is backlit and the subject is too dark. Turning the dial
in the '+' direction overexposes what the camera thinks is right,
allowing more light in, but in doing so my subject becomes better exposed.
Hope this helps :-)
Also, there are different exposure methodologies. If you are shooting
to JPEG, then you want to expose for the final image, and if you lose
all detail in the highlights or the shadows, well there's only so much
you can fit into 8 bits. If you're shooting raw, then you generally
want to "expose to the right", in order to preserve the highlights, and
then process for the final image in post processing. This is
particularly true on ISO invariant cameras such as the K-1, K-3, K-5 ...
Unfortunately, Pentax refuses to believe that people actually use their
cameras as anything but large, expensive point and shoots, and don't
give you a choice for what style of metering you want to optimize for.
There is also the point that the camera is stupid, it doesn't see the
whole scene, or know what is important in that scene.
But in answer to your question, in each metering mode, the camera will
adjust on of the three values, and exposure compensation will affect how
it sets that value. In Av, it is shutter speed, and if you dial in ev
of -1 then rather than setting your shutter speed to 1/100 it would set
it to 1/200. In Tv it's aperture, and Tav it is ISO.
--
Larry Colen [email protected] (postbox on min4est) http://red4est.com/lrc
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