Our digital cameras have a feature called Aspect Ratio. Typically if you go to the aspect ratio function you will find 4:3, 3:2, 16:9, and 1:1. This is the shape of the image captured on the sensor of your camera.
The factory standard (4:3), seen in most cameras is the ratio of height to length of the sensor itself.
If your camera is set to capture images at 4:3 and you want to print a 2X3″ wallet size, a 4X6″ standard print, or a 8X12″ enlargement; your image will be cropped when it is printed. That’s because those sizes when you break them down mathematically are in fact a 3:2 aspect ratio. So are 12X18″, 16X24″, and 23X30″ enlargements.
If you are a grandparent, or if you like to make prints for presents, I recommend you set your camera to 3:2 aspect ratio.
The 16:9 ratio is really for TV/Monitors images, and 1:1 ratios are square shaped, which is very popular these days!
Note: There will be a slight reduction in your digital file size using any other aspect ratio besides 4:3 since the area of capture is reduced to create the new shape. This isn’t really a factor if your camera is over 10 MP.