It has often been said that putting a battery grip onto your digital camera will make you look like a professional photographer*. Perhaps, but that is not the best reason for using one.
Think in terms of the ergonomics of the machine. If you want to take a picture in vertical or portrait mode you are going to have to throw your right wrist over the top of the camera and the weight will depend upon your hand. The grip you need to hold the camera against gravity means more muscle pressure and stiffer muscles. Your hand and arm get very tired over an hour of doing this.
If you use a battery grip your hand remains upright and your muscles are more relaxed. You have the other hand free to operate a zoom lens and the whole rig can be held safely all day.
Plus some camera grips accommodate a second battery in there - you get twice as long to shoot before recharging.
This is evident with the new Fuji X-T1 battery grip - we've just gotten them into stock for the Fuji X-T1 cameras and can particularly recommend them to the users of the large 56mm f:1.2 lens. You can pick one up for $ 329.
* You can look like a professional photographer just by getting a bad haircut...much cheaper.
