Why are there different numbers for ISO when 160, 320 and 640 give exactly the same results?

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Rasskot New Member • Posts: 12
Why are there different numbers for ISO when 160, 320 and 640 give exactly the same results?

Hi. I took raw images with exactly the same settings except ISO. 160, 320 and 640 and they are exactly the same. Not similar but the same. I heard that the sensor is dual gain but there are three settings that give exactly the same results. And in any case the results are equal to single gain sensor. Raw 1/20th f4 with one iso setting give exactly the same results like 1/20th f4 with another or a third ISO setting. I can't shoot in lower light conditions because results do not differ when I spin the iso wheel and there is no point uploading images here because they are exactly the same. I'm losing my mind. Why do I have ISO wheel on my xt4? Is it for video and jpegs?  And when you shoot raw you just put it on 160 320 or 640 and forget about it?  I understand that I sound like a complete lunatic but but after reading so many articles about dual gain and ISO invariant sensors and so many arguments around it I am a bit shocked that the answer is- there is nothing. Your camera doesn't do anything. There are no lifting of Shadows or sacrificing highlights, there is no dual gain- you have one ISO and enjoy it:D do I have a defective camera?

Thanks to anybody who reads this.

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