If you have a Canon 5D Mark II, you will notice the ISO range is impressive – from 100 ISO – 6400 ISO. This ISO range can be further expanded in your Custom Settings to an effective 50 ISO to a whopping 25600 ISO.
You may be thinking who on earth wants to shoot at 25600 ISO; it will produce so much grain! Well, yes, there will be grain, but I have shot at this setting and it wasn’t too bad – for travel and holiday shots and when you don’t have a speedlite handy. I’d never shoot any commercial work on an ISO setting higher than 400 ISO.
How to expand your ISO:
1. Go to the Custom Functions Setting
2. Select C.Fn I: Exposure
3. Scroll through the Exposure options to Option 3: ISO Expansion, and select 1:On
As explained above – shooting on extremely high ISO setting WILL produce grain. But when I’m travelling, most of the images I shoot are “memory shots” and I’d rather have them grainy than ruined by camera shake.
View of Hong Kong from The Peak, shot on an excessively high ISO!