[i2pi]

I was challenged to make a lens for a friend without buying any new optical elements. I have a pile of glass that I've salvaged from old camera lenses that I've modified. I wanted to make a cooke triplet but didn't have any negative elements on hand where I precisely knew their characteristics. I then realized that my eye glasses are relatively well characterized negative lenses, so I had an optometrist cut them into a disc shape and I built the lens around that. It performed very well in my simulations, but not so well in real life. But it was a fun project and my friend ended up with a unique lens for her camera.

[llm_trw]

I swear the only thing that the Bolte Bridge attracts more of than seagulls is photographers.

Also the desktop I have now for ML work is powerful enough to do a full 3d simulation of a lens using the full Maxwell equations from first principles. I remember doing the back of the envelope calculations that I'd need the Bluegene/L back in my undergrad days to do it for real, well: https://bnnbreaking.com/arts/video-gaming/nvidia-geforce-rtx...

What a time to be alive.

[metadat]

> I swear the only thing that the Bolte Bridge attracts more of than seagulls is photographers.

Thanks for encouraging me to search about it, and quickly realize Bolte Bridge is a natural target due to relative level of architectural sophistication as well as being easily accessible.

https://en.wikipedia.org/wiki/Bolte_Bridge#/media/File%3ABol...

[hef19898]

Why would you use ML to develop well understood formulas from first principle, if you can also have a properly developed program for the same purpose?

[jstanley]

I think the ML that the desktop is for, and the optical calculations, are 2 unrelated projects.

[llm_trw]

Yes, OP was doing linear ray tracing to see how the lens would perform on the video. I remember doing the same in a computational physics class way back in the day and talking to the lecturer about what you'd need to simulate real optics without approximations in the equations.

The answer was the worlds fastest super computer at the time. I was a bit shocked that he claimed that was the state of the art for lens manufacture in industry too - no idea how true that was. But figured that if you needed that much computation it made sense.

Well I have 2x that under my desk now and I use it to do local development before I push to cloud machines with 100x the power where the actual work happens.

[itishappy]

Today most commercial lens design software still uses geometric ray tracing. (Even if some can do EM simulations too.)

Not entirely surprising. You want to be able to run stuff a bunch of times to optimize it.

https://www.synopsys.com/content/dam/synopsys/optical-soluti...

[hef19898]

Which would actually make a lot of sense, now that I think about it...

[throwway120385]

You could develop novel lens shapes, for one.

[samstave]

May you please expand? Truly interested

[atoav]

All it takes these days is a piece of aluminum foil and a needle. Tape the foil in front of your sensor (without light leaks), poke a small hole into the center of the resulting spot with the needle.

Takes high ISO settings to get something out of that, but it works and is dead simple.

[Rygian]

You weren't wearing your glasses in real life. That might explain the (apparent) bad performance of the lens compared to simulations? /jk

[hef19898]

My dad is giving photography lessons, and one of the constants are people realizing during session one that they, in fact, do need glasses when the autofocus does not agree with their eyes.

When I borrow my dads camera for the odd shot at times, I totally relly on AF, if I went by the view finder I am almost blind... Same thing the other way round!

[fallinditch]

Sounds like you need to adjust the viewfinder diopter.

[hef19898]

Yeah, we did! Using the other person's viewfinder on the other hand... Well, I trust AF in those cases!

[kuschku]

That's the advantage of an electronic viewfinder :)

[i2pi]

Given that this is HN, I should add that I used the wonderful ray-optics Python package for doing the optical design: https://ray-optics.readthedocs.io/en/latest/

[4gotunameagain]

Amazing project, dreamy images.

"Fingerprint coated" haha !

[Zobat]

The "fingerprint coated" cracked me up as well and that text was already seriously funny.

"...this lens fails to deliver persuasive arguments in nearly all situations..."

LOL

[metadat]

Are you able to share any demonstration pics using your custom lens? Certainly a creative fun project.