Lenses: In their simplest form, safety glasses are like standard ones, but with impact-resistant lenses. More sophisticated versions have ventilated side protection and non-fogging lenses. Safety goggles are the most robust, with safety lenses housed in a flexible plastic frame. Gas welding goggles have a shaded lens. Ear protectors Foam earplugs with a connecting cord for easy removal are relatively cheap and give protection against noise levels above 80 decibels. More expensive - and more effective - are ear capsules or muffs, usually mounted on an adjustable headband, with interchangeable ear pads.
But there was a problem. Artists demanded that cameras be fitted with lenses that would produce images that conformed to the rules of perspective. The image formed by a simple lens-such as a magnifying glass-is circular and dish-shaped; it is not sharp when received on a plane surface. By combining two lenses ground to segments of arcs of different radii a reasonable flatness of field could be obtained. |
Photography
