Camera manuals are never “casual” reading. How many of us actually read the darn things? When your manual really comes in handy, of course, is that moment in the field when your camera doesn’t behave as you expected. Grrr!
While you could carry a copy of your camera manual in your camera bag, chances are it will get lost, torn, or damaged. Here’s a better idea.
Almost every camera manufacturer offers a PDF version of their product manuals. If you’ve got a smart phone with a PDF reader application (iBooks, for example), why not just put copies of all your camera manuals right on your smart phone? Chances are, you will have your phone with you in the field, so do yourself a favor and put your camera references on it too.
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If you have an iPhone, the easiest way to transfer documents to it is via iTunes. Simply download the PDF manual from the manufacturer’s site, then open iTunes. Drag the PDF document icon to the “Books” item in iTunes, and then sync your iPhone. Hint: this trick works with all my eBooks, too.

If you don’t have an iPhone, see if your smart phone has a built-in PDF reader. If not, there are lots of good 3rd-party reader apps out there, too.
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GoodReader is a great choise.
GoodReader is a great choice.
PDF manuals are a must-have on any mobile device.
I always have them on both my computer, my phone and GTab. Of course the GTab is the preferred way, but it is nice, while in the subway or train, to check some features in the manual.
Also something you didn’t mention, I keep a copy of those documents in an online storage. This way, i can always download the files on the go.
Still, the D7000 manual is more than 20Mo, so you might wanna be careful if on 3G.
Since it is all about mobility, which goes very well with photography, I also frequently use a DOF calculator and a NEF viewer (apps I developped on my own, but you can find many apps on the stores).
Earlier this year I started doing exactly what you suggest with all my equipment manuals, except that I’m doing it on an iPod Touch 4G. It’s a great alternative to a smartphone for this and many other features typically associated with smartphones and the fourth generation has a very readable screen. It definitely saves weight and space compared to printed manuals. One other great thing about PDFs is the ability to search the document. Photo equipment manuals typically have poor indexes, but I can usually find what I’m looking for with good search terms. This is a major advantage over repeatedly leafing through a printed manual trying to find something.