Comment by neallindsay | Hacker News Reader

Comment by neallindsay | Hacker News Reader

Like many here, my first thought was "telephoto is just a crop of a wide-angle, so what are they bragging about?" Here's my speculation:

Most lenses are "distortion corrected" because they assume they will be displayed on a flat surface. A little explanation for those not familiar: When you take a picture of a brick wall with your camera parallel to the wall, notice that the bricks on the edge of the photo are the same size as the ones in the center, even though the edge bricks are further away from the camera. This means more pixels are allocated per degree of view near the edge of the field-of-view than at the center.

An "uncorrected" lens is basically what we would call a "fish-eye" lens. Here (ideally) the same number of pixels are in a one-degree circle in the center of the field-of-view as are in a one-degree circle near the edge.

I don't think they would crow about just using an "uncorrected" lens either, so I'm going to guess that this is a "reverse-corrected" lens system where a one-degree circle in the center gets more pixels than it would at the edge. This would be the obvious approach if they want a good center crop but want to capture all the periphery as well.

Exactly; in other words, a telephoto may just be "a crop of a wide-angle," but in a wide-angle lens, the area any given field of view covers on a sensor will always be lower resolution than than if it were spread across the entire sensor by a telephoto lens.

Given the automotive context of this product, I would expect the goal was to maximize the resolution for center FOV (more clearly resolve objects further down the road) while simultaneously maximizing the overall FOV angle (see closer objects in peripheral vision).

In practice, the raw image probably looks like the old Photoshop "bulge" filter, and then somewhere in the image pipeline, it will get reprojected into a regular image that is quite blurry at the edges and becomes increasingly high-res toward the center.

(Another way of looking at this would be that this is an optical adaptation to the uniform, cartesian nature of image sensors, allowing a "foveated" image without a gradation in sensor pixel density.)

This sounds pretty elegant but I don't think it's correct.

I don't have a good sense for what the R&D required to spin up a new bespoke sensor is, but I think it's sort of high - I assume there's a reason Nikon seem to source most of their sensors from Sony. Assuming you get to use a custom sensor for your camera, you also lose a bit of sensitivity at the "fovea."

Also, Nikon's own press release also refer specifically to an "optical lens system with both telephoto and wide-angle lens functions," which leads me to believe this isn't an innovation at the sensor level.

I don't think the parent comment is saying this is a new sensor; rather that the lens spreads the center over a wider area of the sensor (hence more pixels) and squeezes the edges into a smaller area (hence less pixels).

I was talking about the lens achieving the difference in image distribution across the sensor, not a sensor with non-uniform pixels.

I don't think you can get enough difference in the effective focal length to make this worthwhile with a single fisheye like that although I might be wrong.

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