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13 votes

Is there any reason to change the ISO manually?

Is there any reason to change the ISO manually, rather than have it set automatically? The primary reason to set ISO, along with shutter time and aperture, manually would be to totally control ...
Michael C's user avatar
  • 175k
8 votes

What is the physical cause of increasing noise at high ISO?

ISO for Analog vs Digital ISO is confusing in digital photography in part because it was actually meant for film photography. In film photography, ISO 400 really is more sensitive than ISO 100 film. ...
Tim Campbell's user avatar
  • 3,957
5 votes
Accepted

Doubling ISO vs summing pixel values from 2 shots - different?

For #1 and #2. Doubling exposure and stacking two exposures are going to be similar, but not exactly the same. Doubling exposure means you get twice as much signal, for a single unit of read noise. ...
jrista's user avatar
  • 70.7k
4 votes

What is the physical cause of increasing noise at high ISO?

Think of ISO like an amplifier - it increases the gain on the incoming signal. If you have an audio amplifier & an old AM radio tuned to a distant signal, you have to turn up the amp in order to ...
Tetsujin's user avatar
  • 23.4k
3 votes

Should higher ISOs really be preferred (all other things being equal)?

And since the RAW files store the actual voltages read, before any changes to the brightness take place, the values in the RAW file will be the same regardless of the ISO setting. This assumption is ...
Michael C's user avatar
  • 175k
2 votes

What is meant by the "native ISO" when talking about DSLRs?

There is a noticeable difference if you are shooting in a wide light range. An example would be a bright sunny day with high contrast. I have a sony a7r. The native iso is 100 but I can shoot the ...
Steve's user avatar
  • 21
2 votes

What is the physical cause of increasing noise at high ISO?

High ISO does not cause more noise. If you take some photos with equal shutter and aperture at different ISO settings, and adjust them to the same exposure in post-processing, you will not find an ...
adrian's user avatar
  • 131
1 vote
Accepted

Which is the link between a digital ISO value (e.g. 100) and the sensor sensitivity?

The basic exposure formula is fine/simple... exposure = sensor illuminance x sensitivity ÷ 100. But digital exposure is a ratiometric value. First the sensor is given an electrical charge (like a ...
Steven Kersting's user avatar
1 vote

Which is the link between a digital ISO value (e.g. 100) and the sensor sensitivity?

If the base ISO is 100 the digital values are directly converted from analogue signal from sensor. think about schematic like this: sensor->amplifier->ADC So ...
Romeo Ninov's user avatar
  • 12.2k
1 vote

Is there any reason to change the ISO manually?

It isn't Manual Exposure until all 3 parameters have been set to manual: aperture, shutter time, and ISO (video gain). So in situations where you absolutely must have a defined exposure, you must also ...
Jeroen van Duyn's user avatar
1 vote

Is there any reason to change the ISO manually?

The modern camera is loaded with automation. You can elect full automatic -- now you point and compose and take the picture using the setting dictated by the camera’s software. In many cases this ...
Alan Marcus's user avatar
  • 39.3k
1 vote

Is there any reason to change the ISO manually?

Yes, there is. High ISO means lots of noise. Not all photographers want noisy images, although some minor amount of luma noise as opposed to chroma noise may be found pleasant. Also, the auto-...
juhist's user avatar
  • 6,825
1 vote

Is there any reason to change the ISO manually?

yes for sure, High ISO values (like 1600, 3200, 6400) introduce more color noise in your picture which isn't a desired effect. So best to keep it as low as possible* *or as close to the native ISO of ...
Hans Cappelle's user avatar
1 vote

What is the physical cause of increasing noise at high ISO?

Increasing the ISO on a modern digital camera has two effects: It increases the amplification of the sensor signal, making dim parts of the picture brighter. It changes the camera metering so that a ...
Mark Ransom's user avatar
  • 1,495
1 vote

What is the physical cause of increasing noise at high ISO?

Tetsuijn gives already a very good explanation. I try to give a similar explanation but slightly more theoretical. Assume the sensor retrieves the light an all values are between 0 (dark) to 100 (...
Michel Keijzers's user avatar

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