"A fényképen mindig két ember van. A fényképész és a néző."
ISO VALUE, SENSITIVITY
What is ISO?
ISO left behind from the film era of photography. ISO originally referred to the sensitivity of film. ISO refers to the sensitivity—the signal gain—of the camera's sensor. In the case of a digital camera, the images are always taken with the same sensitivity, and the ISO value can be used to set the subsequent digital mount. For digital machines, the ISO value shows how sensitive the sensor surface is to light.
The ISO setting is one of three elements used to control exposure, that works alongside the other two exposure variables – aperture and shutter speed – to determine the overall brightness level of an image.
This value shows how much light our sensor absorbs through a given size aperture over a period of time.
When to set the ISO value? When to use low and high values?
If you need to take photos in poorly lit environments or in low light conditions. Or shooting a subject where the shutter speed cannot be raised for possible blur. Or we need to use a narrower aperture for greater depth of field. Then we’ll need to use a higher ISO value.
ISO is measured in numbers. The default ISO value is usually defined between ISO 50-200 on various digital cameras.
The standard ISO values: ISO 100, ISO 200, ISO 400, ISO 800, ISO 1600, ISO 3200, ISO 6400, etc.
There is a double multiplier between each ISO value. Increasing the ISO from ISO 100 to ISO 200 gives you twice the sensitivity, and raising it from ISO 100 to ISO 1600 gives you 16 times the sensitivity. In the latter case, we can take a clear picture in 16 times less light if all other values are left unchanged.
With the same shutter speed and aperture setting (f5.0 - 1/50 sec - 50mm), increasing the ISO value will make your image clearer. ISO values used (top-down, left-right): ISO 200, ISO 400, ISO 800, ISO 1600, ISO 8000
The problem with high ISO is the noise
It is important to mention that increasing the ISO value will increases the image noise or grain in our photos. Higher light sensitivity results more noise or grain that will appear in our photos, which looks like speckles of color and light randomly strewn across your image.
This means that in addition to the useful signal reaching the sensor, an interference signal is also generated. In practice, this means that disturbing graininess appears in our image. A set of dots of many different colors will be visible, even on homogeneous surfaces. How noisy your photo will be at a certain ISO varies from camera to camera.
Whoever finds what kind of granularity is still acceptable is the saber of individual taste.
It is clear from the images below that increasing the ISO value also significantly increases the image noise. Depending on the type of camera (phone), the ISO value can be set on it, as well as the ISO value and noise level. ISO400, ISO1600, ISO4000 and ISO12800 (Click on the image to enlarge!)
What can we do to avoid noise?
If possible, try to take photos with the lowest possible ISO value. If possible, use a wider aperture or a slower shutter speed instead of raising the ISO. If we have noise reduction in our camera, use noise reduction when post-processing our photo. However, software noise reduction also affects the finer details of our photos, so we lose out on the little details.
How can we set the ISO value?
Setting up on your phone is easier if your phone supports it. All you have to do is drag the ISO value slider in either direction. This setting may be in the PRO photographer settings. If you can't find the setting, try searching the PRO, advanced settings, if not here, look for a photographer's application that knows the ISO setting.
Set the ISO value for cameras
Some cameras have a separate dial to adjust the ISO value. In this case, only the rotation of the dial is required.
For some cameras, we can set the ISO value in the menu.
And for some cameras the ISO setting will be active after holding down a dedicated button and can be adjusted by turning the appropriate dial.
In this case, everything is set by the camera, all we have to do is press the shutter button. This is the fastest solution if you want to react immediately to a situation and trust the camera settings to expose correctly.
P mode - Program EA
The Program AE mode, a semi-automatic mode where the camera automatically sets the aperture and shutter speed, enables you to shoot quickly to capture sudden photographic opportunities, and yet still retain creative control over other settings such as white balance. If necessary, other ISO values can be selected.
M Mode – Manual Exposure
In this mode, you can enter all the settings manually. Note that setting the ISO value does not set the other values automatically.