Well done to all of you. As many of you noticed, we introduced a weekly last week and today I'm happy to say everyone who entered the first one got the answer right. Either you've all got EOS 5D Mark II cameras, or you're good at googling (or should that be 'binging'?) for answers.

For those that didn't enter, let me refresh your memory with the question:
What is the fully expanded ISO range of the EOS 5D Mark II?

The answer of course is 50 (L) - 25,600 (H2).

When you get a new camera, it's important to figure out things like what the expanded ISO range settings are so you know what you can get to if the world is against you and you need to get a shot. That said, it's arguably more important to know how to access the function and how far you're willing to go up the scale to get a shot.

To access ISO expansion on the EOS 5D Mark II, you need to go into the custom function - C.Fn I-03. Here you can activate ISO expansion by choosing setting 1: On. 

With regards to how far you're willing to go, that's a personal choice. If I REALLY need to get a shot, then I'll go all the way to the top, but that's only if there is no other way of getting any more light into the scene. More realistically, I try to keep the ISO setting below 3200.

As for the ISO 50 (L) setting, this I almost never use. To achieve ISO 50, the camera has to do some processing to effectively de-amplify a signal. It's not know exactly how this happens, but it appears that selecting ISO 50 will reduce your dynamic range when compared to ISO 100. So, although you may be able to get a 1 stop longer shutter speed for your flowing water images, if there is quite a wide contrast range you run the risk of not being able to capture all the detail from shadows to highlights. 

If you've not yet entered the second quiz question, go and have a go. And if you can, try to do it without Bing or Google!