BG-E2 ORIGINAL BATTERY GRIP (20/30/40/50D)

Image above for illustration. For sale is actually the BG-E2N model, which is updated with better weather sealing to match that of the 40D and 50D.

This is the original canon battery grip made for 20/30/40/50D, the advantages of it includes having 2 batteries inserted so that it saves the need to change batteries in crucial times of capturing the moment. Also known as vertical grip, it allows the camera to be held in portrait mode without having your arms in the broken wrist position, which is really bad because it reduces the strength in your wrist and hence the stability of the camera setup when taking your shot. This extremely critical especially in low light, low shutter speeds situation, to prevent images plagued with handshake blur. 

The battery grip has two slots for the litium ion batteries to be inserted, and can be done in any order, using one slot, or both together. Third party batteries do not seem to pose any problems as well. Another reason to get the battery grip, would be to use AA batteries in extended shooting durations, when the li-on batteries you brought out are already flat and there is little time or opportunity to get them charged. The included battery tray allows 6AA batteries and can be inserted in replacement of the litium batteries into the grip. This is very useful especially on extended trips to rural areas.

Last but not least, the addition of the vertical grip increases the overall size and shape of the camera, bringing it closer to the shape and size of the traditional "pro" bodies such as the 1D, 1Ds, D2X, D3 etc.. This does help a lot in portraying a professional image in front of paying clients.