It's that time of the week - the weekly quiz results for last week's quiz!

The question was: "Which of these lenses features a Hybrid IS system to correct for angle and shift shake?" 

The answer is the EF 100mm f/2.8L IS Macro USM lens. Well done to 72% of you who entered, guessing correctly. The other 28% all went for the same lens - the EF-S 18-200mm IS lens. 

The Hybrid IS system was announced in July this year, before the EF 100mm Macro IS lens was announced. 

You can read more about the Hybrid IS system in our coverage at the announcement here: Hybrid IS?

In short though, the IS system works to combat two types of camera shake now. A normal IS system compensates for IS of an angular nature. This means that to the camera and lens, camera shake looks like it is a rotation around a point - the point being the camera. However, when shooting with a macro lens camera shake appears to be more of an up and down and side-to-side motion where the whole camera and lens shifts parallel to the subject and this is what the Hybrid IS corrects for. 

Thanks to everyone that entered, keep your eyes out for the next quiz question! 

While the north of England is being thoroughly soaked with rain at the moment, I thought it would be a good time to remind you about the EOS 5D Mark II weather sealing and to put it in context of the rain that's currently falling. 

If any of you have been to my presentations about the EOS 5D Mark II, you'll know there is a story I tell about how weather sealed the camera is - namely that it should withstand three minutes full exposure of light rain, where light rain was defined as 10mm rain per hour.

If we take these figures and put them into the figures for rainfall in Cumbria, just today the news is talking about "another deluge" with up to "10cm" of rain expected to fall. This is being seen as pretty heavy rain, even by our temperate climate standards. If we assume the 10cm of rain will fall evenly over 24hours, that's  0.41cm of rain per hour or, converted to mm, 4.1mm/hour - still quite a way off the 10mm rain/hour.

Now, before you all rush out and soak your EOS 5D Mark II cameras, just remember that until you put a lens on a Camera it is simply a bucket. With that in mind, the lens you use is very important as well - if it's an L series lens with the rubber sealing and weatherproofing, then it stops water entering at the lens mount. But if you use a third party lens like Sigma or Tamron, then with no weather sealing, the camera still, in essence, has a big gaping hole in the front so you need to take the weather sealing figures with a pinch of salt. 

So what's the point I'm trying to make? It's that a) your camera is possibly more weather resistant than you imagine it might be and b) that even with this level of weather sealing Canon don't quote the cameras as being anything special in terms weather sealing unlike some other manufacturers who would be signing this from the roof tops. It's the nature of the conservative approach that Canon have to marketing figures - they like to quote figures by the CIPA standard testing methods and the figures are almost a 'worst case' scenario. 

And.... we're back! Many apologies for the rather scant upgrades over the last few weeks. To say it's been busy would be an understatement.... and it wasn't helped by being on another continent with not much access to to internet.

 Anyway, while we've been 'off-air' I was sent an email asking about memory cards. The question was as follows:
Q: When buying a CF card (or 2) where should you put your money (if
you are like me and don't have much)? Should you get: a) large memory
cards with slower speeds, b) less memory in the card but with faster
write speeds or 3) a happy medium. The follow up to this is "How much does write speed affect video recording?"

The blog seemed like an ideal place to answer this as I'm sure others have asked the question before. 

Pretty much without exception, if you buy a reasonable memory card these days, namely a SanDisk Ultra II or faster, you will have a fast enough memory card in terms of read and write speed. The difference comes when you are shooting sport or long bursts. Here, a faster memory card will mean the camera can clear the buffer faster and hence shoot more images in a burst before buffer lock-out. With some of the newer EOS models, like the EOS 5D Mark II, EOS 50D and EOS 7D, these are compatible with UDMA Class 6 memory cards - like the SanDisk Extreme Pro range of cards. Using a UDMA card in these cameras will result in improved buffer performance.

If you don't shoot bursts, then the only real benefit to faster memory cards is the downloading speed - a faster card will give up its data to a computer quicker so you spend less time waiting for the import to happen - but if this is your concern, you need should also look at the card reader you use. While USB 2 is quite quick, if you want to make use of the fastest cards, you need to use FW800 card readers so the data can transfer to the computer faster. 

As for the effect on video, the cameras that shoot video - EOS 5D Mark II, EOS 7D, EOS-1D Mark IV and EOS 500D, need a minimum write speed of 8MB/sec. The SanDisk Ultra II manages 15-30MB/sec write speed so is more than capable of dealing with the demands of video. With a slower than 8MB/sec card, you will see a buffer signal on the rear LCD. This will gradually decrease as the buffer fills. 

So to answer the question, unless you have a need for it, you don't have to buy the fastest memory cards available. You'll find coming down the range gives more capacity for less money. From that point of view, the SanDisk Extreme III look like a very good choice at the moment - they are available in sizes up to 32GB and are a lot cheaper than going for the top of the range. 

For anyone looking at memory, I came across an interesting oddity in pricing today:

SanDisk Extreme IV 45MB/sec 16GB - £149.99
SanDisk Extreme 60MB/sec 16GB - £99.99

Yes, the faster, newer card is£50 cheaper.....!