Is a back up battery necessary?

I shoot a 1D2n and my batteries are big and juicy, with about 2k shots allowed on my Lenmars. Yet I still bring my spare battery when I head out for an event, just in case it dies or I need to shoot 2.1k or more (:

backup batteries for everything!
body, flash, etc...

I can usually make due with the 2 in the grip for a day, but not every outing starts and ends at home, and not every trip out the door begins with a fully charged set!

I've had a charger die while I was on a trip. Where'd you be without one or more backup batteries then? I also carry spare chargers now.

As for my 5D, I have a backup of a backup of my main in the camera, even if I'm shooting a simple event worth probably 400 shots.

I got a few backup batteries if I am away from home for at least a day. Even being gone for one day and having no backup battery just feels weird. Its cheap insurance, otherwise your carrying a very expensive brick

Yes, two batteries and a backup charger, for when the first one melts from a current surge.

Since electronic shutters have been used in cameras, batteries have always been the photographer's nemesis.. Batteries can fail at anytime, usually when you are getting that all important shot..

I mean let's be realistic.. We spend thousands of buck on our gear and to skimp on something (battery) that actually makes the stuff work is bloody silly..

To me, photography is a hobby, not a "mission". So if something fails on me, it would be a nuisance at worst.

I did buy a spare battery for my former body, but never had to use it because the other one failed or emptied out. I was going to buy a spare for my 5D2 as well, but they were impossible to come by at that time. So far, I have not needed it and I'm not going to buy one until I do.

The old adage "it depends" applies. If you're doing paid stints, shoot a once in a lifetime event, rattle off a bucket load of frames during a single session or use Live View constantly you'll probably want to invest in a spare battery. If you're in it for the fun, you may not need one.

IMO, YES!

Do you ever plan on getting a grip for the camera?

when I shoot for money the spare is ALWAYS with me.
when I shoot for me it's with me about half the time (the other half I generally have 1 body, 1 lens and no bag).

I have 4 batteries for each camera. Running out of juice should never have to be an option

rvdw98 wrote in post #10786830
To me, photography is a hobby, not a "mission". So if something fails on me, it would be a nuisance at worst.

Unless you miss that once in a lifetime shot because you ran out of juice.

4 batteries for the 7D and 2 for the MK3. When shooting all day, I don't want to be caught with a run down battery or two.

My original spare battery for an Eos-3 SLR is still in its original packaging, never been opened. I use two batteries in my 30D at the same time and recharge them up before any important event.