So, not so long ago, many people often would add ISO display in the viewfinder to a wish list of features for the next DLSR from Canon.
I would often poo poo people saying that with experience you get to know if it is high or low depending on how the camera behaved in a given lighting situation, so you didn't need ISO in the viewfinder.
Anyway several models have since been released with this feature, and I have now had one of then for about six months now - a 40D.
So why an I writing? Because I picked up my 20D the other day, and the second thing I noticed (first thing is how small the display is!) was 'where is the ISO display?', so yes I really did miss it, especially the one on the top display.
So I take those words back, it is a tool and like all tools a useful one. I remember people making the same dumb comments about AF when it first came out, I am sure the same discussions were had with cameras that had auto exposure, and more recently there has been the digital vs film thing, a local camera shop went out of business because of his hard line on that!


