Basic Photography | What is "ISO"

Basic Photography - ISO note how sensitive image sensor with amount of light situation. The higher ISO make image sensor more sensitive so possibility to take pictures in low light situations.

ISO in digitals same with ASA in camera that use film roll inside expressed the speed of photographic negative materials

ISO Speed affect Exposure

ISO speed affects the shutter speed / aperture combinations we can use to obtain best  exposure.

Probably our digital camera’s light meter warns have not enough light to correctly expose a picture. We can use flash in our camera, but what should we do if we didn’t allowed to use it or we have no flash in our camera???

We can set ISO in camera higher than before,  or use auto ISO or set our ISO to be manual. But if we set ISO to be manual, me must know how fast ISO  that we need, so we must try to get best exposure

Simulantly, to reduce camera shake we can use higher ISO if we are using shutter speed to slow and we have no tripod and cannot open aperture.

ISO Speed and Noise

Choose higher speed of ISO has effect in our image that we capture. Higher ISO’s speed make our image that we capture make any noise in our image

When we capture image in low light situation, sensor will absorb fainter light signal, at that time sensor will detect noise in every fainter signal.

An image sensor is usually calibrated so that it gives the best image quality (greatest S/N ratio) at its lowest possible ISO speed. For most consumer digital cameras, this value will be expressed as ISO 50, ISO 64 or ISO 100. A few digital cameras use ISO 200 as their lowest ISO speed. So, lower ISO make a better image

ISO Speed with Image Sensor Size Affect

A larger size image need more light to get a good quality image, so that if we in low light situation then we choose large sensor size, noise that we get in our image will be more.

If we take two image sensors, each with 4 megapixels resolution, but of different sizes, the 4 megapixels image sensor that is smaller will exhibit more noise at higher ISOs than the larger one. A digitalSLR (DSLR), on the other hand, uses a large image sensor, usually full frame (24x36 mm) or APS-sized (half-frame). Noise is rarely a problem and the use of a high ISO 400 results in images with barely noticeable noise.