It's a sign of the times.
No one goes into the wilderness for any length of time without their smartphone & camera. Even if the smartphone is a long way from being connected to a service, it is handy for apps, music, notes, and the built-in camera.
When it comes to cameras & wilderness treks, the dSLR kits reign supreme. But being able to capture the sights & sounds of your trek with a high-quality camera will require more power than you might have in a couple of spare batteries. How do you keep your Canon, Nikon, Olympus, Panasonic, Sony, or other dSLA camera fully charged while you are hours or days from the nearest AC outlet?

The solution... Pack your own power!>/p>

1. How Much Power Do You Need?
The first step in choosing a portable power system to keep your camera charged is figuring out how much power you will need.
In my experience, most people using a Canon Mark II will drain their LP-E6 battery pack below 50% each day. I use this Canon model as an example since it is quite common, and the battery size is typical of dSLR cameras.
Since you will want to top-up the battery every day, we will budget an amount equal to the full battery pack's capacity. This will provide a bit of room should we use more power than expected, and to allow for losses in the charging process.

A full dSLR camera battery holds approx 14 Watt-Hours.
Considering losses in the charging process, we will need to replace approx 20 Watt-Hours of power.
Not sure what a "Watt-Hour" is?
A "Watt-Hour" is a measure of power delivered over a span of time. More practically, you can think of it as the relative size of the battery, and we will use this to estimate how long it will take to fill it.

2. Generating Your Own Power
If you are going on a 1 or 2 week trek, it would not be practical to carry upwards of 10 camera batteries. So, let's look at what solar equipment would be required to offset your camera charging needs...

Based on a single dSLR battery each day, you will need to offset 20 Watt-Hours per day or power. In most North American locations, May-Sept, this can be done with a 7-Watt solar panel. A thin film technology is preferred as it is lighter, tolerant of partial shade & overcast conditions, and is flexible. Look for products like the Powerfilm R7 rollable solar panels.

3. Storing Your Power
The power generated by the solar panel must be stored somewhere until needed. By using a lightweight solar storage battery, you will be able to collect power all day, and top-up your camera batteries at camp in the evening.
We recommend a battery pack in the 50 Watt-Hour range. It should be able to provide both USB & 12V output connections, and it should be as compact as possible.
The Voltaic V72 battery is an excellent example of such a battery.

4. Charging Your Camera Batteries
Now that you've generated the power you need each day and have it safely stowed in a solar storage pack, you will need a means of actually charging your dSLR camera batteries.
Note that the charger that came with your camera is designed for use with household AC power sockets, and will not be practical in the wild.

The best way to charge your camera batteries is to choose either a USB charger (for 3.6 & 3.7V camera batteries), or 12V charger (for 7.2 & 7.4V. The charging cradles will resemble the branded-model provided with your camera, but will offer either USB or 12V input which is much more convenient when working with mobile power systems.

Consider a universal battery charger that can adapt to your current camera model's battery, or any other battery model you may end up using in the future.
The Ansmann Vario charger, and the Pixo C-USB charger are excellent universal chargers that adapt to almost every camera battery model on the market.

5. Stick To Your Power Ration
A last bit of advice: stick to your power budget!
Keep an eye on your solar storage battery's power meter, and be careful as to how much power you are using vs how much you are consuming. Being your own electrical utility is fun and liberating, but running out of power in the middle of a trek is not as much.

Need any advice?
Please feel free to contact me with any specific questions.