This is an interesting topic, and it would be nice to see it broadened beyond the narrow world of Canon gear. I also suspect that Brambor is well onto what I can offer. But since this isn’t a private chat …
For sure, getting adequately batteried up for a 12 day hiking trip away from civilization in our digital photo age is a formidable problem. This is especially so if photography is a significant or driving purpose of the venture. I think one point to bear in mind is that your trip is not my trip, and vice-versa. We need to figure out our own parameters.
In the old days of mechanical cameras and film that essentially meant estimating how many shots I was likely to knock off in a day, and from there figuring out how many rolls of film it would take to cover that expectation plus provide for a reasonable reserve. That also is the starting point for today’s digital photo work, except now we have to know two things: (a) how many shots we can get on a given memory card, and (b) how many shots we get out of a battery pack or set of batteries to run the camera.
One quirk I think may be significant is that digital photography invites us to shoot more frames than we did with film.
In the film days I might have planned for two rolls of 36-exposures each per day, average (72 frames), but now easily might shoot twice that many using a digital camera, without batting an eye.
So, let’s say my basic “frames allotment” for the trip is 150 a day saved to the memory card.
With gear presently on hand, I now get right around 600 images on a 4GB card. So I would require about three 4GB cards for the 12 days of hiking. Is that enough? OK, then, toss in a fourth card (at least) just to be safe.
Now, the batteries issue. This – for me – is a lot tougher.
The process begins with a brief digression:
My own first impulse is to shy away from rechargeable battery systems. This stems from having been burned repeatedly by low performing rechargeable technology in years past. It includes, first, both proprietary and generic NiCad rechargeables used to run various flash systems 25-30 years ago (is it really that long ago?!?), and Nikon’s own rechargeable systems used to run the company’s latter 1990s film cameras and early digital cameras of this decade.
However, rechargeable battery packs for Nikon’s current SLR cameras are vastly improved compared to the older stuff. And “vast improvement” hardly does justice to the reality.
If my experience with the current EN-EL4a battery packs powering my (now a generation old) Nikon D2Hs camera is any indication, I’d be comfortable relying on the company’s current rechargeable technology for a 12 day trip. The batteries hold their charges decently, and handle a lot of shooting.
So, let’s say I can comfortably rely on getting about 900 shots out of a single charge on the battery pack. Given my expectation of 150 images a day, presumably two freshly charged battery packs would get me through the 12 day hike. Is that enough?
Well, not for me. I’d be more comfortable with at least three freshly charged packs … just in case. I have two EN-EL4a packs on hand now, and the third would cost another $110. To my way of thinking, that’s an affordable way to go, since the battery really is a long-term reusable item in the kit, just like a camera body. Like a lens or memory card, a battery pack may be usable in several different camera body models -- even newer ones.
What a given battery pack will deliver depends on the pack itself, the camera, the shooting conditions, and your own shooting habits. Pay attention to what you actually are getting out of a battery to project your own needs over several days.
Finally, if I really had my druthers, I’d prefer an option to resort to regular AA batteries – Lithiums, of course – if need be. (I am the sort who wears suspenders and a belt.) When I was shooting film with my Nikon F5 a few years ago a set of 8 AA Liths would get me through 80-90 rolls of 36-exp film. Compare that to the 12-15 rolls of film on a set of 8 AA Alkalines. The Lithium batteries also are significantly lighter in weight.
Certain Nikon digital SLR models allow for the AA battery option (with an accessory battery holder-grip), which makes them attractive to my eye.
G.
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