NSL Photography's™ Glossary of Photographic Terms - G

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Ghost Images
Bright spots of light, often taking the shape of the aperture, which appear in the camera viewfinder or in the final photograph when a lens is pointed at a bright light like the sun. It is controllable through the use of multilayer coating of the lens elements.

GN (Guide number)
flash~to~subject~distance=guide~number/f-stop @ iso, or
f-stop=guide~number/flash~to~subject~distance @iso

The guide number is used to express the power output of the flash unit. It indicates the power of a flash in relation to ISO film speed. Guide numbers are quoted in either meters or feet. Guide numbers are used to calculate the f/stop for correct exposure as follows: Number calculated by multiplying proper flash exposure aperture by the subject distance.

Golden Hours
The “golden hours” are the times of day just after dawn and just before sunset. The name derives from the reddish-golden tones the sun colors everything during those times. The effect is due to the sun's position near the horizon. As a result the sunlight travels through more of the atmosphere, reducing its intensity, and increasing the effect of the illumination which comes from the sky. Shadows are long and pronounced during this time.

Grain
Minute metallic silver deposit, forming in quantity the photographic image. The individual grain is never visible, even in an enlargement, but the random nature of their distribution in the emulsion causes over-lapping, or clumping, which can lead to graininess in the final image.

Graininess
The sand-like or granular appearance of a negative, print, or slide. Graininess becomes more pronounced with faster film and the degree of enlargement. The digital image equivalent of graininess is noise.

Grey Card (18% Grey Card)
Tone used as representative of mid-tone of average subject. The standard grey card reflects 18 per cent of the light falling on it.

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