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Comment by mnw21cam | Hacker News Reader

When a lens is designed, typically an optimiser is used to try to find a combination of lens elements that focuses light of all wavelengths to the same spot across the whole image. If all the same type of glass is used, then it's hard for the optimiser to find a solution that corrects for the chromatic aberration across all the spectrum, because if it adjusts (for instance) something to fix the green aberration then it'll mess up the blue and vice-versa. But if a different type of glass is used such as fluorite, which has a different pattern of chromatic dispersion, then that gives the optimiser an extra degree of freedom, so it is more able to independently control the aberration in the different colours and make a lens that performs well.

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Over the past ten years, lenses have gotten unbelievably better. Apsherical elements have done some of the lifting, and glass formulas another, but how much have computational tools changed how lenses are designed?

Anecdotally, a lot. Modeling of Aspherical elements has gotten better and it is much easier to make them as well. Mamiya made some of the first APO computer corrected lenses back in 1988 - https://lens-db.com/mamiya-apo-sekor-z-350mm-f56-1988/

What are you basing this observation on? I haven't seen any significant improvement in photography or cinema lens performance over many decades. The principles have been understood for 150 years, and using ray-tracing software is standard since the 70s. Cheap lens systems in phones got a lot better, and digital sensors are much more sensitive than film though.

Not who you're replying to, but it seems this is a classic case of mistaking not noticing change is evidence of no change.

I've been following this newsletter for a while as I have a passing interest in (photographic/cinematic) lens design.

https://www.pencilofrays.com/

The main reason why lenses have become significantly better over the last 10-20 years (certainly at the consumer level) is mainly because camera sensors have become significantly better over the last 10-20 years, and therefore the lenses have had to be engineered to a higher standard to avoid the lens foibles being quite so obvious in the higher resolution images that are now possible. The engineering principles are largely the same with a few smaller advances, but to accomodate the demanded-for improvements consumer lenses are now bigger, heavier, more expensive, and have more interesting optical designs. It's purely demand-driven, not technology-driven.

Exactly. It can't be ignored that these new lenses are much bigger & heavier and much more expensive as a result. That helps a lot. But it makes them worse if a) you need to carry them a long way for your type of photography b) your photography doesn't actually benefit from or require their advantages.

A lot of these benefits seem more important to the measurement focused hobbyists. But if you don't actually care about shooting at f/1.2-f/1.4 a lot of the time you might want to save the money.

All you have to do is compare a recent 50mm f/1.4 lens such as the Sigma Art or Sony GM to an older design before the advent of computer-aided optimization (eg the Canon EF 50/1.4).

The new designs are very contrasty and sharp wide open, almost across the frame. The older designs need to be stopped down to achieve critical sharpness, and suffer in the corners. Just so much progress in the past 15 years.

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