Introduction

Th ere is an overwhelming range of image capture mediums now available to the professional and amateur photographer. Th ese range from digital image sensors to various color and black and white fi lm emulsions. Choosing the appropriate medium for the job is an essential skill for every photographer.

Capture mediums

Light-sensitive surfaces can be divided into four main types: ~ Digital image sensors ~ Black and white negative ~ Color negative ~ Color transparency (positive or slide fi lm). Digital image sensors are not interchangeable but most digital cameras allow alteration of the image sensor to its degree of sensitivity to light (ISO setting) and ‘white balance’ adjustments to allow for diff erent light sources used in the illumination of the subject. Color negative and color transparency fi lms are distinguished by a number of identifying labels. Films ending with the suffi x ‘chrome’, e.g. Ektachrome, Fujichrome, are transparency fi lms. Film names ending with the suffi x ‘color’ are negative fi lms, e.g. Fujicolor, Kodacolor. Film boxes will indicate the type of processing required for the fi lm. C-41 indicates the fi lm is a color negative fi lm whilst E-6 indicates the fi lm is a transparency reversal fi lm. Mini-labs are gradually phasing out fi lm processing in favor of digital output, leaving E-6 processing to the professional labs.

Each main fi lm type (negative or positive) is available in 35mm, 120 roll fi lm and 4” x 5” sheet fi lm. 120 roll fi lm is suitable for the entire range of medium-format cameras from the smaller 6 x 4.5cm cameras to the popular 6 x 6cm and 6 x 7cm cameras through to the specialist panoramic cameras shooting frames as wide as 6 x 17cm.

35mm and full frame DSLR image sensor

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Relative size of formats 67

Capture formats

Format refers to the size and shape of an image. A certain amount of confusion can surround this term. It applies to both ‘camera format’ and ‘image format’. An image can be taken or cropped in the vertical or horizontal format using different format image sensors. A vertical image (one that is tall and narrow) is described as ‘portrait format’even if the image is a natural landscape. A horizontal image is described as ‘landscape format’ even if the subject is a portrait. The origins of this terminology date back to when traditional artists were a little more conservative with their intended use of the frame. In editorial work photographers must ensure that images are taken using both vertical and horizontal formats. This gives the graphic artists the flexibility to design creative pages.

Most prosumer digicams and some DSLRs currently available (Olympus and Panasonic) use sensors that have a 4:3 format or ‘aspect ratio’. The aspect ratio is a numerical way of describing the shape of the frame. A 4:3 aspect ratio means that for every unit of height, the width is one and a third times wider. 4:3 is a numerical description of this ratio without using fractions. This aspect ratio may be also be listed as 1.33:1 (this is another way of defining an aspect ratio, i.e. dividing the width by the height). This format is the same as a standard computer screen, e.g. 1024 x 769 pixels. All of the DSLRs made by Canon, Nikon and Sony have image sensors with a 3:2 aspect ratio that matches 35mm film (although only a few of the sensors, described as full frame, are the same size as 35mm film). This is a slightly wider format than 4:3 but not as wide as a wide-screen television that has a 16:9 aspect ratio. Some prosumer digicams now offer 3:2 as an alternative aspect ratio (usually cropped from the 4:3 format in camera) whilst some digicams use a CCD image sensor with a 16:9 format. The aspect ratio of a single page in this book is close to 4:3 whilst a double-page spread from this book is closer to the 3:2 aspect ratio. Care needs to be taken when framing images for editorial work. The photographer has to be prepared to lose some of the visible image in the viewfinder if an editor wants to produce either a full-page or double-page spread from an image captured in a different aspect ratio. Many photographers instinctively design full frame. This can create difficulties when trying to crop the image to a different format.