Why do digital cameras need iso?

A quick Kahn Academy type tutorial on how ISO works. Also includes an explanation of why higher ISO produces more noise at about 5 minutes in.

As for why ISO is there... I simply see it as an additional tool to create the image I want. For instance, I may want a large depth of field, but also need a fast shutter speed. There isn't always enough available light, so increasing the ISO will achieve what I'm looking for.

To paraphrase Crocodile Dundee: "Noise? Call that noise?! Now this is noise."

(f/13 @ 25 sec, ISO 800 - no post-processing whatsoever. Guess the sensor ;-)

http://backup.cambridgeincolour.com/...O/IMG02849.jpg

I wonder how you got that interesting texture effect Ted :)

Quote:

---

Originally Posted by jcuknz

I wonder how you got that interesting texture effect Ted :)

---

Yes, my fine camera is perfect for product shots - but as for high or even medium ISO, fuggeddaboudit.

More, and somewhat better pics in a series, can be seen here:

http://forums.dpreview.com/forums/re...hread=42418604