Lens & Focal Length
Slide the focal length and see the real angle of view it produces, on a full-frame sensor. Runs in your browser — no server call, no tracking.
Focal Length
Field of View
The First Calculated Lens
Joseph Petzval's 1840 portrait lens was the first photographic lens designed through mathematical calculation rather than trial and error — at f/3.6, it was roughly 16 times faster than anything before it, and made studio portrait photography commercially viable for the first time.
The Telephoto Lens
Patented in 1891 by Thomas Rudolphus Dallmeyer, the telephoto design used a diverging rear element to achieve a longer effective focal length in a physically shorter, lighter barrel — the same principle every modern telephoto lens still relies on.
The Zoom Lens Arrives
The Voigtländer Zoomar (1959) is widely credited as the first commercially practical zoom lens for 35mm still photography, letting photographers change focal length without swapping lenses — a convenience earlier photographers simply didn't have.
The Fisheye's Scientific Origin
Physicist Robert W. Wood coined the term "fisheye lens" in 1906 while researching how a fish might see the world from underwater — the extreme wide-angle design was originally built for meteorology, to photograph the entire sky in one exposure, long before it became a creative photographic tool.