I've finally made the decison to buy a larger camera bag to use when I am travelling light. It's always a bit of a trade off, a bigger bag can carry more equipment for sure, but it's also heavier and more of a pain to drag around. My old Billingham rucksack isn't going to thrown away just yet, it's had pretty much constant use for about ten years, and is showing hardly any sign of wear at all. It's just a bit too small to cope with amount of gear I need to travel with these days. Anyway, after a while hunting about I settled on the Calumet BP1500. It's a pretty standard backpack configeration, but one thing puzzled me. The official dimensions of the pack give it's exterior length as being 56.5cm. This is a bit strange as the maximum length of any carry on board baggage at UK airports is now officially 56 cm. I went into town yesterday to have a look at the bag. It's obviously flexible enough to squash down a little to get it into the measuring bins you see all over the airport these days, but I couldn't help but wonder why there was this apparent mismatch. Maybe it's something to do with a conversion from imperial to metric measurements. The guys at Calumet couldn't throw any light on the subject, if anyone knows the whole story I'd love to hear it. Anyway, I've got the bag, and I'm pretty confident it's going to be great. If it lasts as long and as well as the Billingham, I'll be very pleased.