If you shoot digitally in RAW format, the amount of memory taken by your pictures can quickly add up with today’s high resolution cameras. The RAW files on my full-frame Canon 5D II (21MP) take up about 30 megabytes of memory each which means that a normal day’s worth of shooting for me (a few hundred pictures) will require perhaps 5-10 GB of storage. Sports, wildlife and action photographers can easily take several thousand pictures in a day.
On long trips, especially in the wilderness or in developing countries, storage of these images becomes a real challenge. You may not have access to electricity or access only infrequently, weight may be a serious concern especially for grueling treks at high altitude, and finally you may be concerned with theft so you don’t want to take a lot of extra gear (e.g., laptop).
Depending on the situation, I’ve done all of the following on multi-week trips to store my digital images:
Carry lots and lots of memory cards. For my two week trip to Bhutan I took over a 100GB of CF Cards and just barely had enough memory for my images. Memory is cheap now and CF cards can be found for as little as $2/GB.
Carry enough CF cards for 1 day of shooting and use a laptop. I like this solution when I don’t have to worry about weight, power, or theft. I will also take an extra external drive and make sure I have two copies of my files, one of which stays with me at all times. Taking a laptop means that you can start editing and captioning your images right away and you don’t have to wait until you return from your trip.
Carry enough CF cards for 1 day of shooting and use a portable storage device (PSD) or two. A PSD is basically a hard disk with a battery and card reader. You pop the card into the slot and it automatically copies it the disk drive. In the past, I’ve always taken two PSDs to make sure that I have a backup. PSDs have an advantage over a laptop in that they are easier to power and can even run on AA batteries (which are available almost everywhere).
Generally, I prefer solution 1 or 2. With today’s memory prices and ultralight weight laptops/netbooks/tablets, I don’t believe PSDs are a good solution and I expect they will be obsolete very soon. They made more sense in the past when memory prices were much higher.