What is the sensitivity in photography?

Films with ASA (American Standards Institute) or ISO (International Organization for Standardization) grades will show their sensitivity. ISO and ASA grades are the same. Here are some of the most commonly used film sensitivities:

6? 1ISO 100: Suitable for outdoor photography in bright sunlight.

6? 1ISO 200: Suitable for outdoor photography or indoor photography under strong light.

6? 1ISO 400: Suitable for indoor photography.

6? 1ISO 1000 or 1600: Suitable for indoor photography without flashlights.

Once you decide to choose photos or slides, the next factor to decide is the sensitivity of the film. Generally speaking, the relative sensitivity level of the film will be indicated in its name (for example, MYColor Film 200). ISO and ASA sensitivity are usually printed on the box. The higher the number, the faster the film is sensitized, and "faster" means the stronger the sensitivity. When you take pictures of fast moving objects and focus on them, or when you take pictures in a dim environment without additional lighting (such as flash), you need to use fast sensitive film.

The disadvantage of using fast photographic film is that larger silver halide particles are needed to enhance the sensitivity. These larger particles can cause spots or "wood grains" on photos, especially when enlarging 35 mm film negatives. Professional photographers can also use a larger negative to reduce the magnification and reduce the wood grain in the photo. The balance between photographic sensitivity and wood grain shape is an inherent feature of traditional photography. Photographic film manufacturers are also constantly improving to achieve high sensitivity and less wood grain.

Low-sensitivity film is suitable for portraits. At this time, the target is still, you can control the lighting of the target, and you may want to develop a larger photo from the negative. The finer silver halide particles in these films can produce the best results.