Diaphragm, Exposure Time, ISO Rates

In photography there are three main settings that dictate the exposure of an image: exposure time, diaphragm and ISO rate.

Exposure time is the period of time when the image sensor or the photographic film is exposed to light as a photo is being taken. With the help of the diaphragm, the amount of light filtering through the lens can be dictated and the ISO rates provide you with the camera's light sensitivity. The following table shows the connection between the main settings of light exposure. It illustrates the correlation between diaphragm, exposure time and ISO rates. All exposure times in correlation with ISO rates and diaphragm with unvarying lighting result in a uniform brightness on photos. .

For photo brightness it is therefore irrelevant whether or not a photo is taken using settings 1 (ISO/100, diaphram 4, exposure time 1/250s) orsettings 2 (ISO/100, diaphragm 4, exposure time 1/60s). However, there may be significant differences in depth of field or motion blur. There may also be a noticeable difference in quality of image noise if ISO rates are higher. More information about these areas of photography can be found in the articlesShutter Speed, Depth of Field. Further information about ISO rates: Connection between ISO rate and image quality..

 

Diaphragm
2,8
4
5,6
8
11
16
22
32
 
Exposure time
400 ISO
1/2000
1/1000
1/500
1/250
1/125
1/60
1/30
1/15
200 ISO
1/1000
1/500
1/250
1/125
1/60
1/30
1/15
1/8
100 ISO
1/500
1/250
1/125
1/60
1/30
1/15
1/8
1/4

Make sure the exposure times are indicated in fractions (the higher the number after the slash is, the lower the rate). Additionally, note that often only the denominator, i.e. the figures after the slash, is displayed on the camera.

What are ISO rates? Further information on light sensitivity...

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