CCC Forum

There might be something of use in this article, although it seems a simplistic to me.

http://www.amateurphotographer.co.uk/te ... -iii-55225

One thing I did pick up was the author's recommendation to change ISO manually when shooting in aperture priority and low light levels cause the shutter speed to drop. My Canon 7D Mk 1 has a feature which I presume is also present on the 5D111 to set the camera to manual, but leave ISO set to auto. This allows both aperture and shutter speed to be specified by the user, but use the camera's automatic metering to set the exposure by adjusting the ISO. This technique has its limitations, but can be useful when light levels are falling. When I experimented with Auto ISO, I found that I was invariably setting it higher than the camera did when left to its own devices.

Interesting... I'll have to check if my 5Dm3 does this too...

It does, as do even entry-level cameras like my old 550D

It's not foolproof but is definitely useful - when shooting impromptu street photos I normally set a fast shutter speed, f8 or so aperture and leave it in auto-ISO with centre-weighted metering. Pre-focused to whatever distance I'm intending to shoot at.

Gives quite reliable results.

For portraits I'd probably not use it, given so much more of the scene is under my control I'd rather set everything to full manual and tweak from there as needed.