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! 

Recently we've seen cameras simply drive on through the 10MP barrier and now with 15MP and 21MP we have quite amazing files that take up quite large spaces on memory cards and hard disks. They also take quite a lot of computing power to handle them well too. I've noticed a personal trend to be using and EOS-1D Mark III a bit more for work as it produces nice easy to manage files that do all I need them to. I often find that the apetite for memory cards is a real drawback to the EOS 50D and EOS 500D cameras, every time the shutter clicks I can hear my computers groan in anticipation of the onslaught to come.

 Here's some tips that you might want to consider;

• Use SRAW1 on the EOS 5D Mark II or EOS 50D for an easier to manage file, bigger buffer and more shots per memory card
• Plan what you're going to use the video on EOS 500D and EOS 5D Mark II for. If it's youtube or vimeo then maybe 640x480 is fine enough and your computer will love you for it.

In fact in the recent article on the old blog, I shot 720p video on the EOS 500D as I knew the files were going to vimeo and it was quite a pleasant editing experience with a lot less data for the computer to deal with. I also recall shooting some indoor martial arts in the past with an EOS-1D Mark II. The martial arts teachers wanted some shots of a sequence of techniques and shooting the small JPEG images gave me an almost unlimited buffer to capture sequences of linked techniques.

 Let us know in the comments if you have tips to use the smaller image and movies from your cameras.

...Well yes, actually.

Having spent some more time playing around with it yesterday, there are a couple of other things in the update that we thought we should expand on. And it all concerns the movie exposure. Who'd have thought it?!

First up the shutter speed. When you go to manual mode in movie shooting, you don't have complete free reign of all shutter speed and ISO settings. While there is full access to the aperture controls, the shutter speed is limited from 1/30sec to 1/4000sec. This makes a lot of sense as you probably won't be wanting settings outside that range anyway.

The ISO speed is also limited. If you set the ISO to a particular speed, you'll be able to choose anything from 100 to 6400 and the H1 setting of 12,800. However, there is also the Auto ISO setting that you can use which will adjust the ISO between 100 and 6400.

One of the downsides of the manual control of exposure in movies is that instead of doing a very smooth transition between different exposures, as the camera does in auto exposure mode, changing the settings (be it shutter speed, aperture or ISO) will result in a step change in the exposure - there will be no smooth transition in brightness. The Auto ISO setting does rectify this by giving you manual control of your shutter speed and aperture but automatically adjusting the ISO to keep the correct exposure - and you get the smooth transition. I'd love to tell you that that's it and all is completely hunky dory on this front. But I can't. While it all works very well, it you use the Auto ISO setting and combine it with manually set shutter speed and aperture, you then can't use the AE Lock button to keep it at a particular setting. It just doesn't work. You can't over-ride what the camera sees as the 'correct' exposure. Yep, no exposure compensation for brighter or darker subjects in Auto ISO. If you change the shutter speed or aperture, the ISO simply changes to keep the exposure the same - right up and down to its limits. So, unless you're filming mid-tone subjects, we'd suggest staying away from Auto ISO in the manual movie mode.