Over the last few years that I've done 1-2-1 sessions on the EOS-1Series cameras, one question has come up repeatedly in relation to the custom functions - why is there an option to limit the shutter speed range?

There is no one answer, but the one that works for most people to help them get their head round is this:

Imagine you're shooting sport or fast moving wildlife. You're using Av but you want to ensure the shutter speed doesn't drop below a given setting thereby ensuring you will get sharp images. Simply set the lowest shutter speed to be as slow as you are willing to go with the lens you are using. For example, if you are using a 500mm lens and want to keep the shutter speed at 1/500sec or faster, simply set 1/500sec as the slowest possible speed in CFn I-12 with the EOS-1D(s) Mark III and EOS-1D Mark IV. 

This can be combined with Safety Shift (CFn I-8) as well. With Safety Shift set, if you were photographing a subject in bright light at say f/5.6, ISO 400 and the subject moved into the shade - a rugby player in a stadium for example - the first change in exposure would be shutter speed (assuming you are shooting in Av mode). However, if the shutter speed can't drop below 1/500sec this may not be slow enough to get the correct exposure. Safety Shift would then kick in and either open the aperture or adjust the ISO speed depending on which version of Safety Shift you've set. 

Is it a sign that not many of you have EOS-1Series Mk III cameras? Or could it be you need to spend a bit more time with them really getting to know what they have in them and what they can do? (We can help with that if you do.)

Of all the entries we had to last week's quiz question, only 20% of you got it right. The question we asked was:

The answer is 57.

For those of you that said anything other than 57, it's back to school time for you (one or two of you should be ashamed as looking at the results I know you have EOS-1D Mark III cameras and you still got it wrong!). For the 20% that got it right, well done.

For those not intimately familiar with the camera, the EOS-1 Series Mk III breaks up the Custom Functions into four groups:

C.Fn I: Exposure (15 custom functions)
C.Fn II: Image/Flash exposure/Display (9 custom functions)
C.Fn III: Auto focus/Drive (17 custom functions)
C.Fn IV: Operation/Others (16 custom function)

This is largely carried through the entire current EOS range, although the number of custom functions available differs depending on the model. 

So why so many custom functions? The answer is simple - it provides professionals with the most ability to tailor the camera to their way of working and the work they're doing. For a pro, the camera is a tool to do a job. Being able to mould that tool to exactly the way you like to work makes it easier to do the job so having lots of available custom functions is a real advantage. 

If you've not yet entered this week's weekly quiz, go and do so. It'll require some thinking and maybe holding a camera in your hand, good luck! 

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!