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Comment by analog31 | Hacker News Reader

The one thing I can't find is a description of the actual glass optics used. How many elements? What are their individual specs? Etc.

I do some optics design, albeit not photographic lenses. But a f/2.5 lens is not considered to be an easy design problem.

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The sample images show significant vignetting and spherical aberration. The focal plane is curved and clearly not flat over the field of view of the image. There is indeed not obvious chromatic aberration, but I suspect that it is because other issues are significant – there is no mention of the lens's MTF/OTF or any significant tests.

One of the other commenters has highlighted that the lenses in question are part of this telescope kit – https://www.surplusshed.com/pages/item/T1686.html – which is indeed consistent with a reasonably good on-axis or paraxial design but with poor off-axis performance (like most telescopes). I presume these are two apochromatic doublets [1] but it's a bit hard to see.

[1] https://en.wikipedia.org/wiki/Apochromat

I wonder how well software could fix that? Could one of the hack firmwares be modified to correct the lens in camera? Seems like software correction would open a lot of possibilities for DIY lenses.

It’s information completely lost, it can be guessed with DALL-E but I don’t think that’s helpful in lense assessment.

The spherical lense creates a sphere of field of focus. The best way to correct for this is to have a spherical sensor.

Canon and Sony have indeed been working on curved sensor manufacturing, but it seems like a moonshot.

I know next to nothing about how sensors are manufactured, but we do have the technology to build flexible displays. So what are the major challenges in building "flexible" (for lack of a better word, obviously they would be fixed in place) sensors?

I don't think this is correct. The camera is applying a PSF (point spread function) to the image. If you have a known target image you can find the inverse of the PSF and apply that as a correction (deconvolution).

Spherical aberration is caused by the focus deviating across the image, there being only one point in the centre where the image can truly be in focus. So although the image can be improved in the way you describe, you can’t recover the information that is out of focus.

There's a bit of literature out there claiming the opposite. Certainly if you can take multiple Z images you can correct it that way, but there are methods which work directly to de-blur (aka, in focus) an image.

If these methods work, they could make you billions. I’d say go after it!

If you can take some pictures of a known reference field then you can certainly get a significant improvement.

[0] https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.37...

I have to second this, id like to get some more details, this really isnt a trivial task, im curious about the specifics

It's a 65mm diameter achromat. You can see the details in the article at pixelsandprisms.com

> The only parts of the lens that can’t be 3D printed are the glass optics, and for this Steele used Surplus Shed to acquire achromatic (two-part) lenses. He says that eBay is another option, but to make this particular lens builders will need one with a diameter of about 65mm.

Link points to here: https://www.surplusshed.com, perhaps he bought a telescope lens?

I assume it's just very narrow FOV and not achromatic.

From the fine article:

  > The only parts of the lens that can’t be 3D printed are the
  > glass optics, and for this Steele used Surplus Shed to
  > acquire achromatic (two-part) lenses.

I can’t help but feel that’s no longer "3D print… a… lens".

Everything else? Sure, nice job, but not exactly surprising.

In photography, a "lens" generally refers to the mechanical component that houses the optical lens.

In 3D printing, "print" generally refers to "most of the device, except those components that one versed in the field would recognized as being composed of materials not suitable for printing".

Though I do agree with you, many people who do 3D printing would not find the title misleading.

Nope, a lens holder is the mechanical component. Most people and people in industry would refer to either the optical element(s) or the complete assembled optic as the lens.

I am referring to the complete assembled optic.

>> "In photography, a "lens" generally refers to the mechanical component that houses the optical lens."

Where did you hear this? I probably see people use "glass" to refer to lenses as often as I see "lens."

Try Google Images:

https://www.google.com/search?q=photography+lens

You'll see not a single glass lens by itself, but rather every image will be of an assembly containing optical lens intended for mounting to a camera.

Also, enter any photography store and ask to see the lenses. You'll not be presented with discrete glass, but rather with assemblies containing glass intended for mounting to a camera.

Perhaps in the eyeglass industry the term "lens" refers to the glass itself as a discrete component, but not in photography.

In the imaging industry the lens assembly is normally called an objective. In every field I've worked in, the lens is the glass and nothing more. If photography uses this term, it's wrong, but if it's established... who cares, just know that fact and move on.

It makes sense in photography where we don't really deal with or think about individual lens elements aside from people who repair their own, or when some new kind of element appears. We also call the whole assembly glass sometimes, though some people think it's pretentious. It's more common in blogs/YouTube/etc than in actual practice where focal lengths and f-stops are usually the main language of lenses.

The issue is that while you can print 3d lenses (fun read: https://formlabs.com/blog/creating-camera-lenses-with-stereo...), it's just not practical unless you're super into the project (similar for telescope makers who grind their own lenses). The long and short of it is that high quality glass is an industrial process that has hundreds of years of refinement to give you excellent image quality at very low prices.

That said, I have cnc'd a piece of acrylic, polished it, then used it to make a silicone mold and used that to make an epoxy lens.

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