What is Canon zoom lens? ↑
Canon zoom lens or other zoom lens have same characteristic that the focal length (and also angle of view) can be changed, it is opposed to a FFL (fixed focal length) lens (or prime lens).
There are two types of Zoom lens:
Parfocal is the one that maintains focus when you change focal length. It’s also called a true zoom lens.
Varifocal is lens that when you change focal length (zoom in, zoom out) it loses focus. Mostly lenses we use nowaday is varifocal lenses.
Optical zoom and Digital zoom ↑
Optical zoom: It’s a true zoom lens, when you zoom in or zoom out, physically lens move inwards or outwards to get a better view of an object. Optical zoom magnify an object while keeping the resolution and sharpness.
Digital zoom: It simply crops the image at the center area and zoom out with the same ratio as the original. It is the same as when open a image on computer and crop away the edges of the frame, and then enlarge the area you just cropped. With digital zoom the resolution and quality of image are reduced.
What mean 3x, 5x, 10x…on Zoom lens? ↑
That are the ratio of longest to shortest focal lengths on zoom lenses. For example, Canon zoom lens EF 100-400mm F4.5-5.6L IS II USM have longest focal lengths 400mm and shortest focal lengths 100mm, so this lens may be described as a 4:1 or “4×” zoom.
Lens has very large “ratio”, typically more than 5x is called superzoom or hyperzoom.
Telephoto zoom lens ↑
In photography and cinematography, if a lens have long focal length, physically the length of the lens is shorter than focal length is called telephoto lens.
Depend on the focal length, Telephoto lenses have 2 sub-types:
Medium telephoto: Focal length about 67mm to 206mm (it can cover 30° – 10° field of view) in full frame format.
Super telephoto: Focal length more than 300mm (it can cover between 8° through less than 1° field of view).
Some Canon Telephoto zoom lens:
Standard Zoom Lenses ↑
A standard lens or “normal lens”, is one which reproduces a field of view that appears “natural” to a human observer. and which looks natural to the viewer. It have the angle of view around 50°-55° (nearly same as the angle of human eyes).
The focal length of standard lens around 40–50mm (Full-Frame sensor).
Some Canon Standard zoom lens:
Wide-Angle Zoom Lenses ↑
Lens with focal length smaller than focal length of standard lens is wide-angle lens. It allows more of the scene to be included in the photo. It’s very useful to take photo of architectural, interior and landscape. We may not need to go further for taking entire the scene.
Some Canon Ultra-Wide zoom lens: