The “fix” for spherical aberration is one or more aspheric elements - glass whose radius cannot be described simply as the edge of a curve/sphere. Spherical elements are easy to produce - you simply have the glass mounted on one surface and have the grinding (say, sandpaper) element a fixed distance away and you rotate one of them around a fixed point, creating a spherical curve. I own one a few lenses that do this and they yield quite pleasing portraits because of this quality. The edges are sharp and in focus, but the center is subtly out of focus, smoothing out the details. This is called Spherical Aberration and it creates a sort of “smooth yet sharp” feeling to images. Judging by the new mirrorless lenses that are coming out, they’re still bending light back towards the sensor to get closer to the ideal 90° angle, but this is just conjecture. The switch from film to digital has also meant that many of these wide angle lenses with a steep angle of incidence (the light hits the film at an angle that’s far from 90 degrees) don’t play as nicely with digital sensors that have additional pieces to them, such as color filter arrays and IR filters. This means rangefinder (and mirrorless) lenses can often be simpler than their SLR equivalents, and since they have to bend light less, typically have fewer aberrations. This adds size, weight, complexity and increases the chances for aberrations. Typically, though, if the focal length is wider than what can be contained inside the lens, lens manufacturers must add additional lens elements to bend the light back towards the film plane. Leica has some wide angle lenses that protrude into the camera, effectively moving the lens back closer to the film plane. This means that any lens whose focal length is “shorter” (wider) than that, cannot contain the focal length inside the lens itself & some tricks must be played to change this. There are two more arguments for 43mm being the true definition of normal - at least on a 35mm piece of film. Circling the Square (and why 43mm is truly “normal”) I see things as they are, complete and undistorted, if that doesn’t make me a camera I don’t know what does. No? I’m the only one who wonders about these things? I’m not a camera you say? Nonsense.
#35MM VS 50MM CODE#
Is there an ICD code for this? Will my insurance cover it?” Is it possible to be diagnosed as APS-C? I’d better consult the DSM-V.
#35MM VS 50MM FULL#
I know you were losing a lot of sleep over this - endless nights spent tossing and turning wondering “Am I truly normal? What are my aberrations? Are they chromatic or spherical? What if I’m not even full frame, what if I’m - gasp - APS-C. Yes, that’s it definitively, case closed, 43mm is the true definition of “normal.” There can be no more argument on the subject. Just look at how compact and tidy that looks. If we want to know the actual imaging circle of 35mm film we need to calculate the diagonal of a 35mm piece of film - which happens to be 43mm. Those sprocket holes take up a lot of space! Squaring the CircleĪctually, I totally forgot that 35mm film isn’t square. I suppose we could measure the central area of the fovea - the area with the highest density of photoreceptors, but if 210° was too wide, then this would be too narrow.
#35MM VS 50MM PLUS#
Plus our eyes move around a lot, even when we’re not thinking about it, they flit from one object to another - completely skipping past all of the area in between. Of course this is with two eyes, not one eye, and not all of the image is in focus - indeed we can only see the central portion of what we’re looking at in focus.
#35MM VS 50MM PRO#
Pro tip: wiggle your fingers, your peripheral vision is better at picking up movement than subtle shades of fleshy tones.
If you put your arms out to your sides and look forward, bringing them slowly forward until you’re just barely aware of them - they should be basically fully outstretched. The first (flawed) argument for human vision being the starting point for what is a “normal” lens is angle of view.Īccording to Wikipedia, humans can see approximately 210° - or a little more than half of a circle.
This is a slightly flawed argument, but the thought process can lead us to some interesting conclusions. When people try to define what a “normal” lens is, they often go back to the human eye - if the eye is what we use to perceive the world, then the eye must be the very definition of “normal.” Focused light comes through the lens and reaches the retina where light sensitive photoreceptors turn that light into electrical signals. The eye is - for the purposes of this discussion a sphere.