What’s the Fastest Lens Theoretically Possible? And What Would it Look Like?

We’ve told you about some pretty fast lenses in the past — from the legendary Zeiss 50mm f/0.7 lenses made for NASA and used by Stanley Kubrick to film a candle light scene, to X-Ray lenses that you can try to Frankenstein onto your camera body for some strange soft-focus results.

But what is the fastest lens that is theoretically possible? And what would that lens look like? Matt Granger answers those exact questions in the interesting technical video above.

After a quick pitch, Granger jumps in by talking about the fastest lens ever actually made: a ZEISS Super-Q-Gigantar 40mm f/0.33 that doesn’t actually work.

Then, after discussing what has been done, he dives into the numbers to discuss what can be done. Since your F-number (not to be confused with your T-number) is determined by dividing your focal length (in mm) by your aperture diameter (in mm), Granger shows how an f/0.1 lens is theoretically possible if you make a 35mm lens with a 350mm aperture diameter.

Needless to say, theoretically possible and even remotely practical are two very different things. We’re talking about a lens that would have to be at least 36cm in diameter and weigh ridiculous amounts. Plus the area of your image that would be in-focus would be so thin as to be useless, and, the cherry on top: this lens would be obscenely expensive to make.

Regardless of the practicality, the video offers a fun exercise in theory. So if you want to find out more, dive into the theoretical limits of lens optics with Matt Granger in the video up top.

Image credits: Photographs by WestLicht Photographica