exposure compensation...

[DanLoc78]

can someone explain in layman's terms how exactly to use the exposure compensation function? Have a K10D

[Canada_Rockies]

One uses exposure compensation when the subject brightness does not meet the 18% grey your in camera meter expects to see.

The mechanics of using it are to press and hold the [+/-] button while turning the e-dials to get a value other than the one the meter wants. The k10d and k20d give you a graph along which to move the exposure. They will show a line from 0 to whatever you set. I understand that the kxxxd cameras give you the over or under exposure value using digits -2.5 +1.3 or the like. Most Pentax film cameras, such as the MZ-S, use dials to set the compensation.

Uses for exposure compensation would include

• Snow scenes. +1.5 to +2.0
• On the beach +1.0 (light coloured sand)
• On Maui beach, near Hana -1.0 (black sand)
• Portrait, backlit by full sun +2 and check it.
• Dark stage with light subject -2 and check it.

That should give you the idea, I hope.

Enjoy!

[Gooshin]

Originally Posted by DanLoc78

can someone explain in layman's terms how exactly to use the exposure compensation function? Have a K10D

a camera needs to know how much light is in a scene to set the 3 parameters needed for picture taking, aperture, shutter speed, and light sensitivity of the sensor(or film)

over the years methods of measuring light have improved, and will continue to improve, but so far they are not all that perfect (although quite good non the less)

when you take pictures, the camera measures light and takes a picture, however a number of things could fool the camera into measuing an improper amount of light, such as reflective surfaces, super bright lights here and there, and so forth.

in which case you "compensate" by telling the camera that you want "what it thinks +/- X-amount"

also, sometimes various lenses themselves, and their settings can fool the camera, so you have to compensate, altho this often happens after prolongued use of this or that lens, and you just remember the settings, so its not much hassle.


Whether your scene is exposed correctly or not could be gauged from viewing the histogram. For histogram understanding, look here Understanding Histograms

and how much compensation you need to dial in is more of an experience thing than anything.

[tybeck]

Great explanations! The only thing I'd add is that 1 EV = 1 stop. If you read about the Zone System (basically what Canada_Rockies is describing) or some version of it stops might be mentioned instead of "exposure compensation units." I've found exposure compensation so handy when shooting in Av or Tv modes that I set my K10D's one edial to adjust it permanently. I think this feature was added in the last firmware revision.