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What is the fastest lens possible?
  • Vitaliy_KiselevVitaliy_Kiselev

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  • SangyeSangye

    Not a very informative video, and I thought it funny when he suggested that Zeiss could have improved the Otus by making it faster. That reveals his assumption that faster = better. The Otus is a glorious lens, plenty fast enough, and any faster would likely have resulted in optical compromises. Some of the best lenses I've ever used, in terms of microcontrast, sharpness, bokeh quality, and the ever-elusive "three dimensional" quality were f/2, f/2.8, and f/3.5.

    Beyond that, he doesn't even begin to answer his own question. What is the fastest possible lens? Using glass, it'd be around f/0.5. Can't get any faster than that, because at that point you're running up against the limits of glass's refractivity. There are some exotic materials with higher indices of refractivity that in turn could offer faster f/stops, including flint glass, diamond, or germanium for infrared. But these have their limits, and it's incorrect to say that an f/0.1 lens is theoretically possible. Any "theory" in which that is possible fundamentally misapprehends optical physics.

  • joesivjoesiv

    I agree, there wasn't much information in that video. He didn't even mention that the size of the flange puts a hard limit on the size of the aperture. If the aperture is too large, the angle of light trying to get through to the actual sensor will be shaded by the flange/mount.

    But I guess with over engineering, anything is possible, I suppose.

  • goannagoanna

    Does lens boosting somehow not count? I don't think the recent innovations in concentrating light will just go away! I see more lenses incorporating the boosting element.

  • JuMoJuMo

    To help clarify a fairly common misconception: focal reducers are not new technology, they have been around for decades, though mainly for telescope photography, but there are some pretty old custom cine-focal reducers too. The reality is that every lens takes the image projection circle (and thus focal reduction) into account during optical design in order to best suit the sensor size(s) they are designed optimally for. Availability of consumer focal reducer adapters for modern cameras to adapt lenses with enough flange distance, image projection circle and sensor size difference is new - but the technology is nearly antique.

    To be fair, Goanna said "recent innovations", which would include large scale reproduction and consumer availability, so this may not be directed to him at all, but his comment got me thinking about it.

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