@twist you're the one asserting that FUJI use a different ISO to the other manufacturers, so really it
IS up to you to provide evidence in order to educate. As
@Cagey75 says, without evidence to back your statement up, you *could* be spouting nonsense. That you don't seem to want to speaks volumes...
That said, I'd heard previously that Fuji does ISO differently and my interest was piqued enough to google it.
This pdf seemed to cover the basics in a readable fashion (Note, Fuji use ISO SOS and most others use ISO REI. Both are valid under BS 12232:2006).
http://dougkerr.net/Pumpkin/articles/SOS_REI.pdf
This seemed a pertinent extract:
- Standard output sensitivity (SOS) is an objective measure defined in essentially the same fashion as ISO speed (for one of the two bases of ISO speed), but which normally will have a value about 0.71 of the ISO speed.
- Recommended exposure index (REI) is the value the camera manufacturer recommends be used as the exposure index setting. It is not specified to be determined in any specific objective way, but may be chosen empirically to give what the manufacturer feels will be the best exposure results for most users in most cases.
So interestingly as manufacturers who use
REI are using something that in not specified objectively, but relies upon "what the manufacturer feels will be the best exposure", to me it sounds like Fuji are not the ones cheating... Feel free to read all 13 pages. I just skimmed it really, but it seemed to me the point being made was that ISO SOS was measurable, ISO REI was simply just being made up (yes there are formulas, but they still rely upon a number made up by the manufacturer).
If you want to read the full BS 12232:2006 specifications, they are available on Amazon for £98.00 I'd rather spend that money on going somewhere to take photos.
To give balance here. I shoot both Canon (80D and 5D3) and Fuji (X-T2). I don't think I've ever really noticed different ISO values being needed, but then I've never really cared, caring more that the combination of settings give the exposure I want.