So I was over at dpreview reading a rant by someone about how he never needs high iso, and sees no point to designing cameras for high iso performance.
Its something I've heard before on many a post. People who just keep to base iso, so see no point to a d3, or d700, or 5d.
As I drove home last night at 5pm it was pitch black outside. I live in the Northeast US.
It got me thinking, professional work issues aside, I wonder how much more important iso performance is simply based on geography. If you live in southern california like ken rockwell, maybe its not so important. But if I am going to shoot up here past 3pm... it really becomes an issue.
I suppose it all comes back to getting the right camea for what you want to do. But I for one would bet that people living in northern climates with long dark winters spend very little time at base iso.
high ISO is a big deal for me (I live in Florida btw) because alot of my photography happens after the sun goes down or on a highschool baseball field with night lights.
when i leave home for work it's dark and when i'm home again, it's (still) dark So dark that even high iso wont help
Nevertheless i'd love the best hi iso performance. it just gives more control and being able to shoot at what ever setting is nice right? So i'll eventually have something with even better hig iso performance than my current D300. But for now: it's fine, my flashes are helping me out
I live and work in a climate classified as a temperate rain forest. Even on cloudy days, I can shoot at or near base ISO. But I would have to agree that this may be partly a function of where folks live and shoot.
Personally, my only issue regarding the argument on whether good high ISO performance is necessary or not, is the use of high ISO as a crutch or substitute for fast lenses, tripods, flashguns and strobes, etc. I think properly lit subjects with speedlights or studio strobes look better anyway. Even with a high ISO camera, base ISO is better.
So I try to stay at base ISO whenever possible, even with my D700. I will use a faster lens, a tripod, and/or additional light sources before dialing-up ISO. Maybe this is a behavior leftover from shooting film, when the fastest chrome emulsion I used was Provia 400 and the fastest negative film was Fuji Press 800 or Tmax 400, for example.
Sure, it's good to have a camera with superior high ISO performance. For sports and PJ work, it's imperative. For static stuff, other tools and techniques are probably better than just turning up the ISO.
I gotta say, I'm enjoying the added opportunities I have due to the d300 and d700 ISO range. I live in the mountains in Arizona, and we have sun 300+ days a year, but I like to shoot birds & stuff and being able to set the camera to 1/1250th at whatever f stop I want and have the camera wander up into the higher ISOs as I track something into shadows or whatever is nice.
Higher ISOs just give you more 'tools' to use.
Now if I were shooting in a studio, I'd shoot at 200 the whole time because that's where the max DR is, right?
A lot of it depends on what sort of photography you do. Someone who works in a studio with studio lighting will very likely have little need to go to higher ISOs. People who need speed and shoot in natural lighting, on the other hand, will definitely appreciate it. I'm sure everyone would like a camera that performs at both ends, but there are drawbacks either way.
When your camera says a good exposure is 1/60 at f4 with 64 ISO, and the dogs are running through the obstacles fast enough to require 1/800 to stop their action.....well, fast ISO is simply a lifesaver!
When shooting film, my favorite stocks were Agfapan 25 and Ilford PanF 50. If I needed speed, I'd shoot Tri-X, or maybe Ilford's 3200 B&W for fun -- but in general I always wanted to get as close to medium format tonality as possible, and fast film didn't get me there.
With digital, I of course expect more, but even so, my limit for what is tolerable seems to be a lot lower than most people. I found the D80/D200 to be pretty good up to around 320. I'm hoping the D90 will get me up around 800 before the compromises get really frustrating. Anything beyond that, and I'll be ecstatic.
With the use of good Noise removal software (i use Nik Dfine and Noiseware Pro), Iso 800 is where I normally stop with my D80. Obviously if I can stick to base Iso I do. But higher Iso's can be a life saver for those indoor shots where you don't want to use flash.
It's 3:15 with a high, very thin overcast. 1/200th at f4 and ISO 200. It's usually far worse with a heavy overcast being the norm. December is even worse. Some days sunset starts about noon.
So dark that even high iso wont help 
