3 ms·

ISO is supposed to be the sensitivity of the film to light, and the numbers were set by a standards organisation so I'm not sure you can double the number to do

by jemmyw 3y ago

ISO is supposed to be the sensitivity of the film to light, and the numbers were set by a standards organisation so I'm not sure you can double the number to double the effect. Also, how does this even work on a digital camera? Surely we can't actually adjust how sensitive the sensor is to light, so is it just a simulation?

frostburg 3y ago
It's complex. Many modern cameras have dual or triple gain amplifiers, with various range setups. Some ISO settings might be just a digital multiplier on the highest setting of the lower gain stage before switching to the higher gain (which may result in having better snr at higher iso for some settings). Remember that "digital" sensors are mostly analog devices (dealing in continuous voltages).
CorrectHorseBat 3y ago
We can configure the gain of the analog amplifiers
thih9 3y ago
> Also, how does this even work on a digital camera? It’s signal gain of the sensor. “In digital camera systems, an arbitrary relationship between exposure and sensor data values can be achieved by setting the signal gain of the sensor. (…) For digital photo cameras ("digital still cameras"), an exposure index (EI) rating—commonly called ISO setting—is specified by the manufacturer such that the sRGB image files produced by the camera will have a lightness similar to what would be obtained with film of the same EI rating at the same exposure.” Source: https://en.m.wikipedia.org/wiki/Film_speed#Digital_camera_ISO_speed_and_exposure_index https://en.m.wikipedia.org/wiki/Film_speed#Digital_camera_IS...
coldtea 3y ago
Kind of the same it works on film cameras: you change the sensitivity of the emulsion on them, you change the sensitivity of the sensor by raising the gain on the others. Or think of it like changing the gain on an microphone pre-amp before going into a Analog-to-Digital convertor.

by jemmyw 3y ago

frostburg 3y ago

It's complex. Many modern cameras have dual or triple gain amplifiers, with various range setups. Some ISO settings might be just a digital multiplier on the highest setting of the lower gain stage before switching to the higher gain (which may result in having better snr at higher iso for some settings). Remember that "digital" sensors are mostly analog devices (dealing in continuous voltages).

CorrectHorseBat 3y ago

We can configure the gain of the analog amplifiers

thih9 3y ago

> Also, how does this even work on a digital camera? It’s signal gain of the sensor. “In digital camera systems, an arbitrary relationship between exposure and sensor data values can be achieved by setting the signal gain of the sensor. (…) For digital photo cameras ("digital still cameras"), an exposure index (EI) rating—commonly called ISO setting—is specified by the manufacturer such that the sRGB image files produced by the camera will have a lightness similar to what would be obtained with film of the same EI rating at the same exposure.” Source: https://en.m.wikipedia.org/wiki/Film_speed#Digital_camera_ISO_speed_and_exposure_index https://en.m.wikipedia.org/wiki/Film_speed#Digital_camera_IS...

coldtea 3y ago

Kind of the same it works on film cameras: you change the sensitivity of the emulsion on them, you change the sensitivity of the sensor by raising the gain on the others. Or think of it like changing the gain on an microphone pre-amp before going into a Analog-to-Digital convertor.