Camera Trivia 🦍 "Focal Length"
Lenses are mainly divided into two types: zoom and prime. Literally, these refer to variable focal length and fixed focal length, respectively. Their main advantages and disadvantages involve too many factors, so we'll discuss them in a separate topic later 😆
Zoom lenses usually show their mm number as a range, such as 16-35mm f/2.8 or 24-70mm f/2.8, etc.
Prime lenses will only have a single fixed number, such as 35mm f/1.4, 50mm f/1.2, etc.
The mm number indicated actually represents its Focal Length. The smaller the number, the wider the view; the larger the number, the more zoomed in the shot will be.
Taking this AF-10 as an example, 35mm is roughly the field of vision you see with both eyes, while 70mm will be slightly narrower than what you see with one eye. Even in the same scene, the 35mm view will be wider than the 70mm view, with a stronger sense of perspective, but at the same time, more background will be included in the shot. On the other hand, 70mm will have a stronger compression effect, making it easier to crop out unnecessary background elements, and the depth of field will be shallower, which can blur the background to make the subject stand out.
Below are the approximate definitions for different focal lengths:
Less than 21mm: Ultra Wide Angle Lens
21-35mm: Wide Angle Lens
35-70mm: Standard Lens
70-135mm: Medium Telephoto Lens
135-400mm: Telephoto Lens
Greater than 400mm: Super Telephoto Lens
The sample photos of the red dinosaur can roughly show the changes with different lenses. All photos were taken using 200 ISO, 1/200th of a second, and f/4 aperture.
The first 4 photos were taken from a fixed point using different focal lengths. You can see that the subject magnifies as the focal length increases, and the resulting bokeh also becomes more blurred.
The last 3 photos, those enclosed with "Depth of View," demonstrate the changes in perspective when moving the shooting distance to keep the subject size constant. You can see that using a longer focal length results in a softer bokeh and a stronger sense of compression, while using a wide-angle lens can enhance the sense of space, making the subject appear slimmer 🤣.
FOR THE CAPTIONED PICTURES, PLEASE REFER TO INSTAGRAM POST