ISO aperture setting shutter

For the exposure to be correct, there are three variables that must be balanced:

ISO speed : This is sensitivity to light of the sensor array. It defines the total amount of light that required. It is sometimes referred to as the film speed equivalent.

Aperture setting:This is the size of the opening in the lens through which the light passes.It defines the rate at witch light reaches the sensor array.

Shutter speed: This is the length of time the camera shutter is open. It defines how long light is allowed to reach the sensor array.

written by: John Ellis DIGITAL PHOTOGRAPHY

Photo credits: Lazar_x.

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February 25, 2011


Great article

November 23, 2008


The simplest explanation for noise is: Think about what happens when you turn up the volume on your stereo, the sounds goes from nice, hearing all the instruments in the band to loud and with some of the instruments getting drowned out or the music is distorted. The same with the DSLR’s sensor, once you start turning things up, away from normal to loud (low light and high ISO) the image starts to degrade a bit. Until they invent something better than the sensor and amplifier to collect our images we will have to deal with this gain by using our noise reduction setting and/or keeping things normal as possible. Me, like my music I like my images loud but not too noisy.

November 22, 2008


Your explanation about ISO is not quite correct. Actually most cameras, if not all, adjust the camera sensor signal gain in the analogue realm, before the data is transformed into digital information.
Some cameras also employ some digital signal amplification, but that's something like digital zoom.
Also, there is no native ISO. All this still being in the analogue world, things are not "black or white", zero or one. The thing that you call "native" ISO is simply the signal gain setting at which the sensor has the best signal/noise ratio. As power is increased on the sensor in order to amplify the signal, the sensor exists it's normal operating parameters and the noise starts to overcome the meaningful signal, the noise is not created by the digital processor.

November 22, 2008


Just one quick note about ISO in digital photography...

ISO is ALWAYS CONSTANT for sensor of digital camera! You may change the ISO value, but it will be just software operation. If sensor's native ISO is 100 and you will set ISO 400, the only think that happens is that image processor of your camera will multiply values from sensor by 4 (in this case - ISO you set / HW ISO).
So, if You set ISO to non-native value you will degrade the bit resolution of the sensor. If your sensor can read 256 values per color channel and pixel, you will degrade it to only 64 values per channel and pixel (HW) and rest of values will be computed by image processor. This will create digital noise.
It may be handy to set greater ISO and sometimes it is simple needed. But keep in mind, that if it is possible, USE NATIVE ISO RATING OF YOUR CAMERA.

BTW: native != lowest! Most (if not all) Nikon cameras has native ISO 200.

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