Canon ISO Sweet Spot

[ktuli]

All,

I don't know if this was shared here or not (searching for it turned up no hits).... I found this through Wetpixel not too long ago:

Test results for Canon SLR video ISO settings on Vimeo.

The short story is that this guy tested ISO in video mode and found that ISO 160 actually had the least noise, and then multiples of 160 (ie: 320, 640, etc) are better as well (ie: 640 is better than 400).

Interestingly, the study also found that 160 is the best ISO for still photography on Canon cameras...

So you might want to bump that ISO setting a little...

- Bill

[Black Pearl]

This will be the actual base sensitivity of the sensor without the need to amplify the signal - some Nikon bodies (my D300s included) have a base sensitivity of 200iso.

I challenge anyone to demonstrate the difference in any real world situation though.

[Colin Southern]

It doesn't actually add up; most manufacturers vary the gain of the amplifier before the signal hits the analog to digital converter for "full stop" ISO steps (100, 200, 400, etc), and then make any intermediate adjustments digitally by under exposing and then digitally shifting the data up 1/3 or 2/3 of a stop.

So there's no real "sweet spot" (IMO) - just maximum dynamic range at the lowest true ISO, decreasing with each increase in ISO

[ktuli]

In all fairness, the test was specifically just for noise. So I suppose this sweet spot is to reduce noise... which is not necessarily the same as the best quality image.

- Bill

[Colin Southern]

In all fairness, the test was specifically just for noise. So I suppose this sweet spot is to reduce noise... which is not necessarily the same as the best quality image.

- Bill

That's my point though Bill, unless they've changed the way they do it, higher part-stop ISOs should give more noise because changing base gain is always cleaner - so you get the base noise + the noise floor being moved up 1/3 or 2/3 of a stop at an intermediate step. All theory though - in practice, so long as the image isn't under-exposed or excessively cropped, I don't find noise an issue at any ISO setting.