Why not ISO 100?

[Geoff]

Can anyone please explain to me why the D700 is listed as having;

ISO 200 - 6400 (with boost up to ISO 25600 and down to ISO 100)

Why is the ISO not listed as 'ISO 100 - 6400' ?

I'm a little confused.

[gstark]

Can anyone please explain to me why the D700 is listed as having;

ISO 200 - 6400 (with boost up to ISO 25600 and down to ISO 100)

Why is the ISO not listed as 'ISO 100 - 6400' ?

Yes. Next question, please.

[Geoff]

Ok then (for the pedants) -

Why is it that the D700 is listed as having;

ISO 200 - 6400 (with boost up to ISO 25600 and down to ISO 100)

Why is the ISO not listed as 'ISO 100 - 6400' ?

[chrisk]

i believe that this is just nikon speak for the optimal range.

peak DR is now at iso200 rather than iso100 so thats whats recommended for "normal shooting." similalrly, at hi-iso's 6400 still retains a very good degree of DR and if you go above that, (boost or whatever they all it), its achievable, but quality significantly degrades from there.

i think its strange to not list the whole range awswell but it does make sense in a curious way i spoose. i suspect its to encourage people to be using iso200 especially at the lower end given that its been drilled in our heads for so long that "peak performance" is at iso100.

[gstark]

Ahhh ... the real questions come out.

In the various Nikon cameras (not just the D3), and at the ends of the ISO spectrum, the actual ratings are not calibrated, and thus they choose to not rate them as actual ISO values. It's more of an approximate ISO, rather than and actual, accurate one.

[Geoff]

Thanks Rooz (and Pedant ) very helpful indeed.

[Murray Foote]

As well as that my understanding is that for ISO100 the values are extrapolated so that there is no quality advantage from ISO200 and there may be a decline.

[Grev]

As well as that my understanding is that for ISO100 the values are extrapolated so that there is no quality advantage from ISO200 and there may be a decline.

It's not true actually.

I've tried different scenes on my D300, while at the pixel peeping level, noise can be seen in dark areas even at 200iso (very high contrast scene and very nit picky pixel peeping btw), and there isn't noise at 100iso, but the dynamic does shift to the shadows side at 100iso and at 200iso it retains more highlights.

I do wonder what methods Nikon use to raise iso at high values though, as in actual electronic (hardware) or maths (software).

[dviv]

Maybe it's to make it look like the camera goes to a higher ISO than it really does?

[Yi-P]

I do wonder what methods Nikon use to raise iso at high values though, as in actual electronic (hardware) or maths (software).

I believe they usually start at around ISO 200 which they did calibrate extensively. After that, it is using hardware amplification to increase the signal at that base level to 'higher ISO'. As Gary said, things are calibrated to meet standards at ISO200-6400. After that, maybe a kick in with software+hardware amplification for an increase of the 'base signal' and reduce noise in the signal using software+hardware.

The case for ISO 100 I can think of is that they just pass the signal through the hardware and reduce the base signal by a half.

[Murray Foote]

As well as that my understanding is that for ISO100 the values are extrapolated so that there is no quality advantage from ISO200 and there may be a decline.

It's not true actually.

I've tried different scenes on my D300, while at the pixel peeping level, noise can be seen in dark areas even at 200iso (very high contrast scene and very nit picky pixel peeping btw), and there isn't noise at 100iso, but the dynamic does shift to the shadows side at 100iso and at 200iso it retains more highlights.

I do wonder what methods Nikon use to raise iso at high values though, as in actual electronic (hardware) or maths (software).

Well I could test it myself but I've been more concerned about the other end. What you say suggests you are comparing two images at different effective exposures and that you would need to fine tune the ISO "100" exposure with incremental adjustments of shutter or aperture in order to start from the same effective exposure. As I say, though, I'm only relaying what I've read and I don't remember in what way the ISOs lower than 200 were deemed inferior. It may have been dynamic range rather than noise, for example. Also, with the same effective exposure, you might have different findings for noise.

[Grev]

I believe they usually start at around ISO 200 which they did calibrate extensively. After that, it is using hardware amplification to increase the signal at that base level to 'higher ISO'. As Gary said, things are calibrated to meet standards at ISO200-6400. After that, maybe a kick in with software+hardware amplification for an increase of the 'base signal' and reduce noise in the signal using software+hardware.

The case for ISO 100 I can think of is that they just pass the signal through the hardware and reduce the base signal by a half.

So with that in mind, how does Canon do it?

Well I could test it myself but I've been more concerned about the other end. What you say suggests you are comparing two images at different effective exposures and that you would need to fine tune the ISO "100" exposure with incremental adjustments of shutter or aperture in order to start from the same effective exposure. As I say, though, I'm only relaying what I've read and I don't remember in what way the ISOs lower than 200 were deemed inferior. It may have been dynamic range rather than noise, for example. Also, with the same effective exposure, you might have different findings for noise.

Well I don't think it's inferior, I tried it and it's actually lower noise but less highlight range, safe for studio conditions. And those uncalibrated ISO values seems quite 'accurate' to me as well, I don't think it's even out by a 1/3 of a stop.

[rampotta]

My camera is D2h

just support iso 200-1600

[moz]

Most DSLR sensors these days have max dynamic range from ~400-800 ISO and outside that you start to lose a bit. But since it's hard to display what they have anyway, it's not too critical I'd still like less noise at even higher ISO, but lower ISO I can take or leave (mostly it gets used when the camera changes it to keep the other parameters within the ranges I've set... I love variable ISO)