The mirror-free camera revolution was designed to provide smaller, lightweight camera equipment, but in fact, camera manufacturers have just used to make bigger, better lenses. Why comes down to the lens's physique.
Manipulating focal length is complicated
A lens focal length that we have looked at in depth before-is the distance between the back node point and the focal point. In a simple convex lens, it is the distance between the center of the lens and the focal point. However, no camera lens is a simple convex lens; They are all "composite lenses" that are lenses made of a combination of individual lenses called "lens elements".
Cameras have a "flange focal length" which is the distance between the lens bracket and the sensor. For Canon DSLRs, for example, it is 44mm. The problem for camera manufacturers is that manipulating focal length is complicated and generally adds more lens elements that make things bigger and heavier. The reason that the Canon EF 40mm lens is the smallest is that it closely matches the focal length of the flange and thus requires very few lens elements.
The farther you move from the focal length, in what direction, the greater a lens will be. A 600 mm lens does not have to be 60 cm long, but because it should not be 60 cm long, which would be a simple convex lens, the optical structure is complicated. It's the same with an 11mm fisheye lens.
There is a small sweet spot between about 24mm and 50mm where it is possible to make lenses that are not as large, but for anything else, the optic to manipulate focal lengths is a significant barrier to miniaturization.
Aperture is a hard limit
Aperture is a function of focal length. When we talk about f / 5.6, what we are saying is that the lens's iris is open to focal length divided by 5.6. For example, a 50mm at f / 2 has a lens iris opening of 25mm; At f / 8 the iris is open to 6.25 mm.
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While this is not a concern for wide-angle lens, it becomes very fast a problem for fast phone lenses. Take the incredibly popular Canon 70-200 f / 2.8: At 70mm, the lens's iris is 25mm wide, but at 200mm it's 71.5mm. This means that the adoption of infinitely thin material is the smallest size of the front of the lens about 72 mm, in fact it is 88.8 mm, and just can not be done less.
No matter what Canon or Nikon or Sony wild, they can not physically make a 200mm f / 2.8 lens with a front element less than 80mm or so. Physics laws will not move.
Technical developments are a problem
A lot of old lenses were just not very good. They had charm, but the autofocus was off, there was regular heavy vignetting or distortion, and the image was not sharp across the frame. Modern lenses have solved many of these problems by adding more lens elements, which, of course, adds greater size and weight.
Similarly, modern developments like powerful image stabilization add even greater importance to already heavy objects.
And let's not forget about zoom lenses. A magnifying lens will always (almost) be smaller and lighter than a zoom lens that covers the same focal length because they are much easier. Zoom lenses take you guess, more lens elements and moving parts.
Really is the physics problem
What the problem is with is that the laws of physics are a pain in the ass.
Optics are a well-managed and complicated field. Manipulate light to remove objects appearing closer or nearby objects appear farther away, while striking the backgrounds or keeping everything in focus, maintaining high image quality requires only heavy heavy lenses.
The dream of professional cameras gets less is just the moment: a dream.
Image Credit: lightpoet / Shuterstock, LeonRW