Those "in-between" ISOs...

[Daniel Browning]

Or have I made an incorrect assumption? I'm working from the premise that "hardware ISO" (for lack of a better term) is 1) complicated to configure, requiring different strategies for different bodies, 2) demands continual R&D money, and 3) is susceptible to malfunction. Maybe #3 is no longer a concern, but it is one more electrical system that could conceivably break down.

I think we have a misunderstanding. I have no problem with the hardware ISO (analog gain): ISO 200, 400, 800, and 1600. They're great and I want to keep them as an option. The only problem I have is with the software ISO (digital gain applied in camera): including the high ISO (3200, 6400), low ISO (50), and tweeners (50, 160, 250, 320, 500, etc.).


Instead of doing the digital manipulations in the camera like they are now, Canon should allow the user to do them in post.

On the other hand, perhaps the cost, when you consider the deals and arrangements that Canon must have with RAW converter manufacturers, not to mention their own DPP...they may have to recode their products...or would they?

It's so simple that it takes less than a dozen lines of Matlab code to load the entire raw file and apply the EC. In any case, Canon has no qualms about breaking compatibility and other raw converters. They even added "metadata ISO" in the form of HTP, which some raw converters ignore and others support incompletely (Adobe).

Getting back to the real-world implications
- if I may. Those "extra stops," the ones we lose when we use higher ISOs -
they're gone forever, right?

Right.

No RAW converter can get them back because,
to the converter, they don't exist. Those HLs have been pushed off the scale and were simply not captured
during exposure.

Right. Of course if it is only one or two channels that were lost, some converters will try to "guess" what the correct values would have been, but that's a separate thing.

The trade off is that we get (the same amount?) footroom - we get the low range frequencies. Do I understand that all correctly?

There is no trade off between metadata ISO and in-camera digtal ISO.
It's all negatives. You get clipped highlights, bigger files, and
reduced precision.


There is a trade-off between low analog ISO and high analog ISO: high ISO reduces headroom but increases footroom.