In this article we will try to understand the meaning of numbers in the lens aperture, and why the larger lens aperture (the smaller the f number) the more expensive the price of a lens?
Have you ever wondered, where the aperture unit is usually expressed in numbers like the f / 4, f/5.6 or f/22 (or too f4, f5.6 or f22) come from? and why the greater diameter of the lens and the lens the smaller physical size of the figure?
Have you ever wondered, where the aperture unit is usually expressed in numbers like the f / 4, f/5.6 or f/22 (or too f4, f5.6 or f22) come from? and why the greater diameter of the lens and the lens the smaller physical size of the figure?
The image above shows a comparison between the physical size of the Canon 50mm f/1.2L lens and a 60mm f/1.4. Aperture scale figures stated above comes from the comparison between the focal length of the lens and the size of the diameter of the lens:
aperture = focal length / diameter
For example, if we had a 50mm lens and an optical diameter of the front lens is 25mm, then we have a lens f / 2 (or also often expressed as f2)
aperture = 50:25 = 2
If the focal length (what the focal length) lens and a 50mm lens diameter 50mm, maximum aperture means the lens is f / 1. In figure f / 1, the diameter of the lens is 2 times larger than f / 2, and there are 2 stop difference between f / 1 and f / 2 (still remember the sense stop you?). And lens f / 1 can be passed 4 times more light than the lens f / 2 aperture so that the greater the faster and more good use in low light conditions.
You are now starting to realize why not many lenses 50mm f / 1. There are only a dash aperture lenses f / 1, such as the Canon EF 50mm f/1.0L USM which is discontinuous (see the photos produced from superb lens 50mm f / 1 here). Lens with aperture lens f1 requires a large body size, large optical elements that can be equal to the diameter of its focal length.
aperture = focal length / diameter
For example, if we had a 50mm lens and an optical diameter of the front lens is 25mm, then we have a lens f / 2 (or also often expressed as f2)
aperture = 50:25 = 2
If the focal length (what the focal length) lens and a 50mm lens diameter 50mm, maximum aperture means the lens is f / 1. In figure f / 1, the diameter of the lens is 2 times larger than f / 2, and there are 2 stop difference between f / 1 and f / 2 (still remember the sense stop you?). And lens f / 1 can be passed 4 times more light than the lens f / 2 aperture so that the greater the faster and more good use in low light conditions.
You are now starting to realize why not many lenses 50mm f / 1. There are only a dash aperture lenses f / 1, such as the Canon EF 50mm f/1.0L USM which is discontinuous (see the photos produced from superb lens 50mm f / 1 here). Lens with aperture lens f1 requires a large body size, large optical elements that can be equal to the diameter of its focal length.
It also helps explain why there is a big difference in the way the price of the lens focal length is the same but different maximum aperture. For example, try to compare the Canon 85mm f/1.2 lens and Canon 85mm f/1.8. Canon 85mm f/1.2L lens sold at a price above USD 20 million while the 85mm f/1.8 lens costs around Rp 4 million. If we return again from the formula above, then to produce a 85mm lens with f/1.8 aperture, with a 47mm diameter lens enough (85/1.8 = 47.2). While to get the f/1.2 aperture, 85mm lens diameter had to be about 70 mm, almost twice as big is not it? The more material, the more optical and made it harder = more expensive.