ISO is the measurement of the camera's sensor/film sensitivity to light. It is one of the 3 ways to create a well exposed image (The other two being Aperture and Shutter Speed). Typically, a higher ISO for a correctly exposed image will result in the image being more noisy/grainy.
Questions tagged [iso]
324 questions
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Where do ISO numbers come from?
I understand how an ISO number affects the film sensitivity or a digital image, but I'm curious where did the numbers come from? How come we talk about ISO 100, 200, 400, and so on instead of ISO 1, 2, 4 or some other arbitrary sequence of numbers…
ahockley
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Why isn't expanded ISO settings (L / ISO50) enabled on Canon DSLR's by default?
It bothers me a bit when I have to hunt through menus to find the 'enable expanded ISO settings' setting in my 5D mkIII.
I'd like to know why the low ISO's are disabled however and if there is any technical reason for it?
NULLZ
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Comparison of camera sensitivity
There are different ways to quote the sensitivity of cameras. Usually it's quoted in ISO or ASA.
ASA and/or ISO is usually reasonably well-defined in the absence of any deviating statement as ISO 5800. Yet there are additional, newer ISO norms, like…
planetmaker
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Why do some DSLRs have ISO less than 100?
The lowest ISO value in most cameras is 100. But some have less than 100. Why is that so? Does that mean these are more sensitive? And how low can the value be?
Anil Joseph
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ISO when shooting at night
Why does the signal to noise ratio decrease when using high ISO speeds (e.g 3200) when shooting at night with a digital camera?
user3574
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Highest possible ISO?
What is the theoretical upper limit on ISO for a digital image sensor?
(I imagine any limit must be a function of sensor pixel size, since once all electronic noise has been eliminated then shot noise dominates and that can only be reduced by…
feetwet
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how many stops different are a 100 ISO film stock and an EI 320 film stock, and which is faster
how many stops different are a 100 ISO film stock and an EI320 film stock , and which is faster?
Jingjing Yang
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System Gain vs ISO
Does the "system gain" (i.e. electrons/ADU) change when one changes the ISO of a digital camera? To put this another way is there an analog amplifier between the sensor and the ADC whose gain is programmed to change when the ISO setting is changed?
Peter Pershan
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What is happening in the sensor when you change the ISO?
I understand the relationship between ISO, aperture and shutter speed. What I'd like to know is what actually happens in the sensor when you raise or lower the ISO number? In other words, what is taking place electronically?
Joetsu
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What's the difference between Program AE (mode P) and ISO priority?
In both of them you choose an iso, and the camera automatically set shutter speed and aperture. So what's the difference?
I'm using Canon EOS 4000D, where there is only Program AE (mode P), but I've seen ISO priority in other cameras. So I was…
user1883212
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Is ISO better analogized as how big your bucket is, or putting rocks into the bucket?
Which of the two embolded phrases below is more correct?
Serindu. 643 points 1 year ago*
Taking a picture is like filling up a bucket of water. The shutter speed is how long you keep the hose on. The aperture is how big the hose is. And the ISO…
user81115