Are all ISO's created Equally ?

[kirbinster]

Most typically shoot at ISO 200, 400, 800, 1600, etc... but these seem to be throwbacks to film days. Are intermediate ISO settings such as 640 just as good to use as these "whole" number ISO's? In other words does quality suffer at all because they are somehow interpolated or are they just as "clean" as the whole numbers?

[Doug Pardee]

Originally Posted by kirbinster

Are intermediate ISO settings such as 640 just as good to use as these "whole" number ISO's? In other words does quality suffer at all because they are somehow interpolated or are they just as "clean" as the whole numbers?

It depends on the camera model.

[dcclark]

Originally Posted by Doug Pardee

It depends on the camera model.

I'm pretty sure that on most modern cameras, the "odd" ISOs are just as good as their nearby "whole number" neighbors. After all, ISO corresponds to amping up the power to (and signal from) the sensor... so ISO 640 is just a bit less of an amping-up than ISO 800. The power applied to the sensor is a continuous, not a discrete, thing, so "ISO 800" is really just a particular power level which has been calibrated to match the ISO standard.

[OsmosisStudios]

I just find it easier to use whole stops, but if I only need a third or two, then i'll do that without hesitation

[BCampbell]

I guess what you're trying to ask is, since ISO 100, 200, 400, 800, etc. correspond to popular film ranges of ASA 100, 200, etc, are other ISO levels "real" or somehow interpolated.

I think the answer is that there have been (and still are to the best of my knowledge) ASA 640 film, as well as many other ratings: 32, 64, 125, 160, 320, 1250, etc. What's available to you is based on the sensor and processor.

[wulf]

Do many cameras give the option of setting partial stops or do most rely on allowing auto-ISO? My Nikon D40 only allows me to set 200, 400, 800, 1600 and "HI1" but, then again, it is only a basic model.

Wulf

[OsmosisStudios]

Wulf: D80 and up allow for third-stop increments in aperture, shutter speed and ISO.

[kirbinster]

My D5000, D90, and D300 all allow: L1.0, L0.7, L0.3, 200, 250, 320, 400, 500, 640, 800, 1000, 1250, 1600, 2000,2500, 3200, H0.3, H0.7, H1.0 to be manual set. In auto ISO modes they come up with some funky numbers inbetween as needed.

[Sterling]

IMO, the ISO numbers aren't any funkier than f/7.1 or f/6.3 or any other setting that a digital camera can choose. they're all just numbers. The more familiar or "whole" ones aren't any better or worse.

[Dave_s]

Originally Posted by kirbinster

Most typically shoot at ISO 200, 400, 800, 1600, etc... but these seem to be throwbacks to film days. Are intermediate ISO settings such as 640 just as good to use as these "whole" number ISO's? In other words does quality suffer at all because they are somehow interpolated or are they just as "clean" as the whole numbers?

I'm confused. Didn't you ever shoot asa 640 before digital?
It's nothing odd or new.

I also shot 64 Kodachrome all the time.