Some older cameras were fitted with "convertible" lenses of normal focal length; the front element could be unscrewed, leaving a lens of twice the focal length and angle of view, and half the aperture.
The front element could be unscrewed, leaving a lens of twice the focal length and angle of view, and half the aperture. Some older cameras were fitted with "convertible" lenses of normal focal length.
Some older cameras were fitted with "convertible" lenses of normal focal length. The front element could be unscrewed, leaving a lens of twice the focal length and angle of view, and half the aperture.
Some older cameras were fitted with "convertible" lenses of normal focal length. The front element could be unscrewed, leaving a lens of twice the focal length and angle of view, and half the aperture.