'Flash Compensation'

[Alan T]

I have made extensive use of the adjustable flash intensity on my Z1012 recently, when photographing frosty subjects (nice one at http://forums.steves-digicams.com/fo...mp;forum_id=85). Usually I want to tone it down, to achieve a better balance with ambient lighting, but of course how much depends on the subject distance. I have had to use a great deal of trial & error (and battery power!).

I am intrigued that on my Z712 and Z1012, the flash intensity is adjustable in the same style of steps as exposure value, i.e., -1.0, -0.7, -0.3, 0, +0.3, +0.7 +1.0.

Every other camera I've had has simply been on or off, or else 'low, medium, or high'.

Entertainingly, the 'extended' manual for the Z1012 clearly shows, in two separate LCD screen shots, a 'flash compensation' setting of +2.0, which isn't actually available on that camera or on the Z712.

Is it possible that the 0.3 step really is equivalent to an EV step of 0.3 in the flash intensity at a given distance, so that +1 flash compensation would allow 1 stop smaller or a 1.4x timesincrease in guide number?

Does anyone know how other manufacturers grade flash levels? Does anyone know how the automatic exposure system works when using 'compulsory' or 'auto' flash?

[dancheng]

Hi Alan,

Interesting question. I also want to know the answer.

Perhaps, you may like to experiment a bit. For instance, try taking a picture of -0.3 flash with +0.3 EV. Compare it with another one of 0 flash with 0 EV. I may be talking non-sense here.

Daniel