View Full Version : ISO, ISO-Bracket

Ulfric M Douglas
14th November 2010, 06:31 PM
Well I was faffing about with my wife's e-600 and decided to try ISO-bracket, set to +_1EV.
So I took the three shots and found 9 files.
Oh I see, I thought, like WB-bracket it takes one frame and does the 3-ISO bracket to that one frame. OK, I only need to take one exposure to create 3 photographs ... cool ...
But how can this be, I thought? surely ISO changes as the camera pumps volts into the sensor to change its sensitivity, then takes the picture.
Aha, this ISO-bracket must be 'pretending' to change the real ISO sensitivity of the sensor and giving me three 'simulated' results.
So, a fair challenge to test. Having written down the ISO results from the first three-from-one picture I set about replicating the result using three shots in which I set ISO before taking single pictures.
First was ISO 1600, next 800, next 3200 and I was shoving the _+EV up and down (or down and up) by one stop to get the same results.
I'm doing this in A rather than M, no matter.
(I shall not post the crops of this here Fudge packet and side of drawers, no.)
What I found was my three manually-set ISO photos were indistinguishable from the ISO-bracketed three-from-one-exposure that the camera had created.
So ... what's the camera/sensor/pipeline/software really doing when I ask for and ISO 3200 shot or an ISO 200 shot?? :confused: