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Can someone explain how ISO/Base ISO functions these days? (alien.top)

submitted 1 year ago by Spirit-Subject@alien.top to c/photography@viewfinder.pro

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So generally, I’ve always understood that the lowest ISO is best to shoot at. Though with newer cameras, they usually have a higher base ISO and in some cases Dual ISO.

I usually work with the R5C, even for photography. It feels odd to take portraits at 800 ISO because I’ve always been told it should be as low as possible.

So does the Base ISO system, negate the need to shoot at lowest ISO for the clearest and least grainy image?

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[–] Spirit-Subject@alien.top 1 points 1 year ago (2 children)

I understand that very well. My question is that, does Base ISO on your camera signify the cleanest image in all settings?

[–] Sneezart@alien.top 1 points 1 year ago

Yes, base or native ISO will produce the least noise in a correctly exposed image.

[–] TiMouton@alien.top 1 points 1 year ago (1 children)

While u/sneezeart answer is correct, I would like to add some details:

Native ISO is the natural ISO range that your sensor can handle without extra digital manipulation. So for example that would be like ISO100-6400 as a native range and the low setting (ISO50) and high setting (iso12800) would be extended ISO as they are digitally manipulated.

Base ISO is the lowest ISO in the cameras native range. Base ISO yields best image quality as it’s the sensors base sensitivity without amplification (gain) through increased voltage.

If base ISO is 100, that means at ISO 200 the signal of the sensor is amplified with twice the voltage. The more amplification, the more noise.

[–] oldlurker114@alien.top 1 points 1 year ago

Native ISO is the natural ISO range that your sensor can handle without extra digital manipulation

The image sensor has no ISO range, or ISO setting at all.

Typically different ISO settings on the camera cause the sensor to be operated with different parameters (leading to different noise performance curve). May sound like nitpicking, but I think it's important to understand the difference.

So for example that would be like ISO100-6400 as a native range and the low setting (ISO50) and high setting (iso12800) would be extended ISO as they are digitally manipulated.

This is wrong.

Typically the image sensor operates at the same setting at "extended low ISOs" and with the "lowest normal ISO" (though some extended settings may use the same parameters of ISO 125 or ISO 160 for example). What is different is metering - with the extended settings the camera exposure program simply causes a larger exposure to be used by default, thus there will be less headroom (in the JPGs, thus no longer ISO standard compliant). That's it.

The "extended high" settings on the other hand typically add (digital) multiplication to the data. All it does for raw is that it cuts the headroom. For JPG shooters it's not relevant if it's "extended high" or not.