I made a bad camera lens from some old glasses [video] • Hacker News Board

Re: I made a bad camera lens from some old glasses [video]

#61

Post by blagie » Tue, Mar 05, 2024, 11:54 AM UTC

ddalex wrote: post #33

blagie wrote: post #26

Earlier quoted context omitted.

Sort of. My universe broke when Sigma introduced an 18-35mm f/1.8 zoom. An f/1.8 zoom. Wow. And it was optically brilliant. Seventies lenses are super-sharp, but that's because they're mostly slow primes. Any modern prime stepped down to f/5.6 -- even cheap consumerific ones -- will be super-sharp. There's nothing in seventies technology which allows lenses to have the aperture, zoom range, and aberrations of modern…

> it was optically brilliant Of course, if it's a F/1.8

That's not how it works. The wider the aperture, the worse the aberrations. IF you can make a lens usable at f/1.8, it will be tack-sharp stepped down. That's why wide primes have a reputation for being super-sharp.

Roughly the same optical design, limited to f/2.8, will be better in all respects.

A good way to think about this -- oversimplified obviously -- is you have a bunch of functions you're trying to cancel with e.g. a linear combination. If you look really close to the center, it's already a flat line. If you step out a little, two are adequate (have the slopes cancel). As you go further and further out, things become increasingly wonky. That's why you have super-complex designs for an f/1.8 zoom -- to get that cancellation right -- but even a single element works fine at f/22.

There actually were f/1.8 zooms all along, but for applications which didn't demand that sharpness (TV and CCTV). You can pick those up cheap and see what happens. They're sometimes fun on a real camera too (many will span a μ4/3 sensor with just a tad of vignetting).

Re: I made a bad camera lens from some old glasses [video]

#62

Post by blagie » Tue, Mar 05, 2024, 12:04 PM UTC

hef19898 wrote: post #27

blagie wrote: post #26

Earlier quoted context omitted.

Sort of. My universe broke when Sigma introduced an 18-35mm f/1.8 zoom. An f/1.8 zoom. Wow. And it was optically brilliant. Seventies lenses are super-sharp, but that's because they're mostly slow primes. Any modern prime stepped down to f/5.6 -- even cheap consumerific ones -- will be super-sharp. There's nothing in seventies technology which allows lenses to have the aperture, zoom range, and aberrations of modern…

Appertures, well, those f2.8 Nikkor telephotos from that period still demand high prices for a reason. And f4.5 isn't that slow, even compared to modern zooms. Or those old 50/1.4 (agreed, the 1.8 versions seem to be tad better) and other 1.8 primes. Still great glass. Or those unaffordable NOCT lenses... Not sure what I would need one for so. What those old lenses have so, is build quality. They are machnical master…

Virtually nothing, except weight, was sacrificed to make the 18-35mm f/1.8 zoom. That's why it's impressive.

It's possible due to things like:

- Much better lens coatings (allowing for more elements without flare)

- Computer modelling

- Being able to better machine aspherical elements

On integrated cameras, like an RX100, we can do even better due to digital. We don't need low-distortion, but just well-characterized distortion which a computer can invert.

Those old lenses -- at least the ones still working -- do have build quality. Adjust their prices at the time for inflation, and have a look at modern Zeiss, Leica, and other premium lenses. You'll see similar build quality.

For fun, next time you're looking at old lenses, pick up a Quantaray too, for fun. Or most older (before around 2000) Sigma lenses. Or other off-brands. You'll see unparalleled build quality, but in the other direction -- eighties-era plastic. The optical quality is bad. Not "fun" bad, "vintage" bad, or "whimsical" bad, but just bad.

When we look at older stuff, we tend to look at stuff which stuck around, but even that Quantaray is high-end compared to an older consumer camera. Most people who owned a camera had a non-SLR one. You looked through a little window on top, and the pictures were shot through the main lens. Those were even worse. Or a disposable (a single plastic element lens).

Re: I made a bad camera lens from some old glasses [video]

#63

Post by dr_kiszonka » Tue, Mar 05, 2024, 7:54 PM UTC

munificent wrote: post #45

CPLX wrote: post #16

If you want to get this effect quickly without spending any money at all, and you have a pro-type camera with a removable lens, you can get it by just holding the lens against the opening, and rocking it side to side a little. It's a pretty common trick photographers and videographers use to get a sort of dream-sequence effect.

If you want to spend some money and have something a little more stable and usable (and less likely to get dust on your sensor), the Lensbaby Edge 80 and Sweet 80 lenses produce a similar effect and are tons of fun. I did learn that they must be used judiciously. After shooting most of a personal music video with a Sweet 80 wide open, my wife described it as "like watching an ocular migraine".

Lovely feedback from your wife!

I don't know anything about photography. Is using specialized lenses like the ones you mentioned better than postprocessing software?

Re: I made a bad camera lens from some old glasses [video]

#64

Post by munificent » Wed, Mar 06, 2024, 12:04 AM UTC

dr_kiszonka wrote: post #63

munificent wrote: post #45

Earlier quoted context omitted.

If you want to spend some money and have something a little more stable and usable (and less likely to get dust on your sensor), the Lensbaby Edge 80 and Sweet 80 lenses produce a similar effect and are tons of fun. I did learn that they must be used judiciously. After shooting most of a personal music video with a Sweet 80 wide open, my wife described it as "like watching an ocular migraine".

Lovely feedback from your wife! I don't know anything about photography. Is using specialized lenses like the ones you mentioned better than postprocessing software?

"Better" is a highly subjective term.

But lenses can do things that postprocessing can't do, strictly speaking (though it can often emulate well enough to fool most people).

The input to a lens is a field of photons that are:

1. Striking the sensor at different places. In other words, which pixel they hit.

2. Coming into the sensor at different directions.

3. Coming in at different wavelengths.

The 2D image captured by a sensor completely discards 2 and it drops a significant amount of information from 3 on the floor by bucketing all wavelengths into red, green, and blue amplitudes designed to mostly mimic human visual perception.

Lenses have access to the whole shebang.