Digital Camera Help - What Is A Fisheye Lens?

Fisheye lens - The fisheye lens produces a distinctive curve or circular image by using an ultra wide-angle lens.

Digital Camera Help - What Is Focal Length?

What is focal length?

Focal length is the measurement of an in focus object to the lens. A super wide-angle lens has the shortest focal length and a super telephoto lens has the longest focal length, see below for view ranges of focal length of different lenses.

Less than 20mm - Super Wide Angle Lens
24mm - 35mm - Wide Angle Lens
50mm - Normal Lens
80mm - 300mm - Telephoto Lens
More than 300mm - Super Telephoto Lens

Digital Camera Help - What Is Depth Of Field?

Depth of field (sometimes abbreviated DOF) is a term which refers to the distance between the nearest and farthest objects which remain "sharp" (in focus) in a photograph.