Originally Posted by canoli
Yes. Some of the ISO settings use analog gain (amplifiers), but many of them are just digital manipulations.
Originally Posted by canoli
I should point out that they used to have this feature on the Canon 10D. It disappeared from all later cameras.
I can think of several possible reasons:
* Because they can. Customers accept all sorts of compromises at high ISO, even ones that are completely unnecessary (like this). Many photographers never even use high ISO. Canon knows that few people use it and the ones who do just have to be willing to accept additional unnecessary compromises.
* Because of Customer Service. Some customers will have a rude awakening when they realize that Canon has been deleting 1, 2, or more stops of their highlight headroom for no reason. Even if Canon buries the metadata feature in some custom function, and provides copious documentation, many customers will get thoroughly confused about what it is or does. Misconceptions will travel rapidly on the web about it, no doubt. Even some raw processing programs might get confused by the metadata. Adobe, for example, doesn't implement HTP correctly, it just does a linear push without preserving highlights. Other converters might not apply the push at all, so customers will wonder why it's too dark.
* Because of Management. Canon had ISO metadata in the 10D, but removed it in all later cameras. It may have been removed on purpose, by edict from Management. Software engineers wouldn't remove a feature that was doing the obviously correct thing and replace it with the obviously incorrect thing for no good reason. A good reason would be if the manager said "cripple the camera or I break-a-you-face."
* Because of Marketing. Perhaps the feature was removed because Canon wanted to save that trick for a rainy day, so they could come out with a new camera with "2 stops more dynamic range at ISO 6400!" without any development cost. If they were nefarious enough, they could sell a firmware update to all cameras going back to the 20D offering ISO 25600 as metadata, with 4 stops more dynamic range across all cameras. Sony sells $1,000 firmware upgrades on some of its high end video cameras, so there's precedent.
* Because of Engineering. It's possible that the software engineers responsible for the firmware are unaware of the issue, but given the high level of competence they've demonstrated I think that's highly unlikely. I don't think Hanlon's razor applies.
* Because of Bureaucracy. This is the most likely reason, IMHO. Many suboptimal things happen in big corporations. Maybe the 10D metadata ISO feature did not have the correct "addition of feature form" filled out, and the engineer who added it was fired because he didn't follow the correct procedure for requesting authority to add a new feature. Maybe the paperwork for removing the feature was easier than the paperwork required for leaving it in.
Who knows.