I don't know how many point and shoot cameras I've seen die in the desert especially the cameras with the extending lens barrel. Two P&S cameras died on the last trip with was nothing special as far as dust or sand in the atmosphere is concerned.
Having a $4000 camera and $5000 worth of L glass out there can be a bit of a worry sometimes particularly when there is a lot of dust being kicked around by either the wind or just peoples foot steps. Keeping the gear clean is a fundamental practice in my usual shooting environment but it all comes down to common sense.
I keep everything in the bag at all times and always keep the bag closed tightly, the only time it stays open is when I need a working area for when I change lenses or to perform other tasks. The bag that I use in the field is a Lowepro Vortex 200 which I think is an excellent bag for carrying and protecting a lot of gear. With all my gear plus a well stocked first aid kit it weighs about 9Kg despite the weight it is quite a comfortable backpack with a good weight dispersal straps on the chest and hips.
The bag really does have excellent padding and I have no worries about slinging it around the tracks and running into obstacles but obviously this i kept to a minimum.
The biggest danger to the gear out here is not the bumps and knocks but the insidious dust and sand the is everywhere and I mean everywhere I go. When the bag is on the ground it stays closed because even light footsteps kick up the fine dust and with 14 people around me this is a very real problem. Most of the time when in sandy country I still keep it on my back regardless of how long we stay at a spot.
The L lenses are the best lenses to use out here with way more environmental sealing than standard lenses. However my new 24-70 f/2.8 USM does have an extending/retracting barrel and this is something that I really did have to think about. Every time that lens is pushed in and out it sucks that volume of air in and out as well so I am twice as conscious of dust on this lens. Dust on the front elements will always happen and for this I take care of it quickly with a rocket air blower and a bush its only after these have been used that I will use a lens cloth.
I use B+W UV Haze filters on all 3 of my lenses and its only when I'm using my B+W Polarizer I remove them out in the field. Many people say many things about using UV filters to protect the lens but for me its a necessity and I have no doubt that using these filters saves me so many headaches. So far I have not totally destroyed a filter but my first 77mm Hoya Pro 1 has a lot more scratches than I would ever want on one of my lenses. If your shooting in a studio yeah don't use them but for me I'm out there walking and swinging my 5D MKII around most of the day so the benefits of protection out weigh any other argument.
So this whole post came about when I was cleaning my 24-70 f/2.8L this morning with some of the best lens cleaner Formula MC. I found this cleaner on the website www.2filter.com and I've used it to clean the front elements of all my L lenses and have be totally impressed by it. It is amazing just how much dirt you can remove from the cleanest looking lens or filter. The image is the grime that I removed from my polarizer filter this morning and its only been about 3 weeks since I last gave it a clean.
Formula MC is the only fluid I will use on my lens but I use a range of other tools to remove dust. The most useful of all is the rocket blower from Giotto, I have this thing in my bag or in my pocket constantly while shooting. The rocket blower produces a jet of air the removes 99% of dust and dirt that lands on the lens instantly and without pushing it across the glass. For quick removal of finger prints I'll use a Lens Pen but these will eventually fill up with gunk so they need to be replaced. The Lens Pen is rubbed across the surface so you'll need to make sure that your not pushing a grain of sand across the surface.
So far the sensor of the 5D MKII has remained relatively free of dust thanks to the built in auto clean and the rocket blower. I'm not sure of what I would do if some dust did settle on the sensor so I'll write about that when it happens.
My previous camera a 400D was used for more than a year and it still doesn't have a single scratch on it thanks to the best protection system I've ever found. Camera Armor is the best thing for total protection of the body so much so that the LCD on the 400D looks as good as it did the day I bought it. I was told by a rep from the company that the Camera Armor for the 5D MKII will be out towards the middle of this year. This is not good news for me as I already have scratches on the 5D MKII LCD screen, not many but still more than I have on the 400D. I want my Camera Armor now!
All these items add up to a good maintenance system for the camera but the best bit of advice I would give would be do it regularly. If you let it build up on the lens or body you have far more chance of doing permanent damage to the equipment.