On the X10, the auto ISO and manual ISO settings are all on the same menu. Which can be accessed by the fn button (or now also from the raw button). On the X100, there's an ISO menu with settings from 100 - 12,800. The ability to turn AUTO iso on or off is controlled from a completely separate menu that's not even in the same root menu - the ISO is in the shooting menu and the Auto ISO is in the other (utilities or settings or something?) menu. If you turn auto ISO on, you can also choose the maximum ISO and the minimum shutter speed you'd like met at the expense of higher ISOs in that same menu. To set the minimum ISO, however, you have to go back to the manual ISO menu and whatever ISO you've set there is the minimum that AUTO ISO will use. This system is fine if you almost never want to change from auto to manual ISO. If you just set it up for auto, which I usually end up doing, you set it up once and forget about it. If you want to set it for manual, you set it once and forget about it and just use the fn button to access and change ISO quickly and easily. But if you're shooting in manual ISO for a while and then want to switch to auto, you have to first remember to leave the manual ISO setting at the level you want to serve as the minimum ISO once you switch to auto. And then you have to go menu diving to go find the auto ISO on/off switch. This is OK for changing back and forth once in a while, but I often find myself in situations where I'm happy to be shooting in auto-ISO and then want to take manual control for a handful of shots, for whatever reason. So I have to go back to the bottom menu, find AUTO ISO and turn it off and then take manual control. Minor hassle. Then when I want to go back to auto iso, I have to go back into the menus to turn auto ISO back on and then go back to the manual ISO menu to make sure I didn't have that set at something like 1600 or 3200 because if I did, that's the LOWEST it will go in auto iso. With the second firmware update, they did make this a bit easier by allowing you to change what's handled by the fn button by holding that button down for a couple of seconds - it takes you to that menu which happens to be located near the Auto ISO menu item on the same menu, so if you remember, its a bit of a shortcut to that menu item.
But its silly to have to go through all of those hoops just to do something as simple as changing between auto and manual iso. EVERY other camera I've used has ONE ISO menu that covers everything. The X10 is a perfect example with a list from 100-12,800 followed by another list of auto-400 through auto-3200 (sometimes the available range is reduced depending on other settings). One menu - one slightly longer list. A very simple matter to change between auto and manual. The Ricohs are the same - one list that contains both auto and manual ISO settings and a separate menu to set the minimum shutter speed you want to prioritize at the expense of higher auto ISO settings. I've never seen it done like its done on the X100 and I can't begin to imagine who'd have thought of that and WHY, on God's green earth they'd conclude it was a better idea???
This is not among the great problems that confront mankind, mind you. I've lived very happily with the X100 since last April and I plan for keeping it for a good long time even if they never address this. But I'm offended by it. Its a pet peeve. Its not a deal-breaker, but its just plain stupid. STUPID STUPID STUPID! See, I get worked up by this!
We all have little things that won't determine the fate of the earth but that piss us off anyway and this is mine in the camera world. I would think and hope its a relatively easy FW fix, but even if its a king-hell difficult one, I'd really like to see them take it on.
-Ray