Easel: a holder to keep sensitized material, normally paper, flat & in position on the baseboard of an enlarger during projection printing

EI: see exposure index

Electronic flash:  a tube containing gas that produces a brief, brilliant flash of light when electrified and is reusable.  Also called a strobe

Emulsion a light-sensitive coating applied to photographic films or papers.  It consists of silver halide crystals & other chemicals suspended in gelatin

Enlarger an optical instrument ordinarily used to project an image of a negative onto sensitized paper.  More accurately called a projection printer because it can project an image that is smaller or larger than the negative.  Enlargers are categorized as being either: condenser, diffuser, cold light, or variable contrast, depending on the type of light source used and the types of condenser lenses or diffuser mixing chambers through which the light passes, and the types of filters used.

EV:  see exposure value

Existing light:  see available light

Exposure:  the act of letting light fall on a light-sensitive material, or the amount of light reaching the light-sensitive material, especially the intensity of light multiplied by the length of time it falls onto the material

Exposure index a film speed rating similar to an ISO rating; abbreviated EI

Exposure meter:  an instrument that measures the amount of light falling on a subject (incident light) or emitted or reflected by a subject (reflected light), allowing aperture and shutter speed setting to be computed. Commonly called a light meter

Exposure value:  a system originally intended to simplify exposure calculations by assigning standardized number values to f-stop and shutter speed combinations.  More often, used as shorthand way of describing the range of light levels within which equipment operates.