3 ms·
No, it is the opposite. A 50mm f/1.4 lens focus the light and the heath much more than a 300mm f/5.6. You were quite lucky with your camera I guess.
by tigershark 9y ago
No, it is the opposite. A 50mm f/1.4 lens focus the light and the heath much more than a 300mm f/5.6.
You were quite lucky with your camera I guess.
- 4ad 9y agoCorrect. The flux for the sun on the sensor/film/whatever is: Φ/4α² * 1/A² Where Φ is the sun flux at the surface of the earth, and α is the angular diameter of the sun. A is the f-number of the lens, the only variable in this equation. It doesn't depend on focal length. The total power over the film is: Φ/4πα * f²/A² which does depend on focal length, but that is usually not the determinant factor, as for surface burns the damage depends mostly on the flux.