A couple of questions about the D5100

If you are capturing in very cold weather and in live view mode, then definitely you should consider a back-up battery. On last Christmas, I captured more than 300 images (around 200 for a time lapse sequence of sunrise) - one battery was enough. On NYE again I captured around 300 images (night time, temperature around 20 C) (around 150 images for a time lapse) - one battery was enough.

But few days back, I capture around 150 images in an evening and I was utilizing Live view mode, I had to change my battery.

The camera will come with a charger, but new battery will not.

If you want to maintain the same exposure throughout then you have to shoot in 'M' (manual mode. But if you want to compensate the variable light during a sunset/sunrise then better you shoot in 'A' (aperture priority) mode and let the camera take care of shutter speed.

On Christmas day sunrise time lapse, I used 'A' mode, the camera automatically altered the shutter speed to compensate the increasing light.

On NYE, I shoot in 'M' mode as I wanted the same exposure in throughout the sequence as my light condition was not changing.

Hope I answered your queries. Get the D5100 - you will not regret. Current price is the cherry on top

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