17. CMOS Vs CCD, Sensor Formats, Continued

Another interesting detail is the size of the sensors. Modern digital camera design is based on traditional film camera design in which the image format is 24 mm x 36 mm. Hence the designation 24x36. This type of format produces a rather elongated image of which the scaling can be changed in proportion to 10x15 cm, 13x18 cm, etc. In practice, automatic photo printing machines offer paper formats that are adapted to 24x36. An enlargement without a margin will produce an image with bleed without unacceptable reframing. The same applies to a print with a margin of equal size all around the print.

Schema 1/1,8'' (7.18 x 5.32 mm), 1/2.7" (5.27 x 3.96 mm), 2/3'' (8.80 x 6.60 mm) APS (22.7 mm x 15.1 mm), 24 x 36 mm

Matters are complicated when CCD and CMOS sensors are used because their format is smaller than 24x36 and the ratio between them is not the same either. Consequently, the image is smaller, but it is also "squarer." This produces certain problems when printing and framing, as can be shown in the illustrative photo. The commonest sensor sizes include 1/1.8'' (7.18 x 5.32 mm), 2/3'' (8.80 x 6.60 mm), and 1/2.7 (5.27 x 3.96 mm). Into this very small space, the manufacturers are able to "pack" 2, 3, 4, 5, and even 6 million pixels, which then produces problems of sensitivity, since reducing the number of photosensitive cells also makes them less sensitive to light. This is where noise problems clash with the resolution of the sensors. The sensors in the 300D are in the APS format with a ratio of 3:2 (22.7 mm x 15.1 mm).