His invisible father holding up the light meter, adjusting the f-number, staring down into the ground-glass screen of the twin-lens reflex. |
The lower the f-number the faster the lens and, in theory, the more light it lets in. |
The configuration offers the advantage of high image quality, low distortion, and low f-number, making it ideal for spectral imaging. |
The light intensity reaching the film is inversely proportional to the square of the diaphragm f-number. |