I've read suggestions that using ISO-160 (and higher multiples such as 320, 640 etc) may give better results than ISO-100, 400 etc. This was on a 40D and also a 1Dmk3. Although it seems surprising that the higher ISO might produce better quality images, the suggestion was that this was because 160 was the native ISO on these cameras.
Using 160 instead of 100 isn't going to make much difference to shutter speeds, but I'm wondering if anyone finds this makes a difference to picture quality?
That's been my experience with the 40D. Don't have a 1D3 so can't help ya there.
There's definitely less noise with the "new" native settings. In fact I took the 1/3 stop
off and have gone to full stop clicks for ISO. I currently have the 400 f5.6L glued to it
and just love the IQ at ISO640 shootin' wide open.
elluDe wrote:
I've read suggestions that using ISO-160 (and higher multiples such as 320, 640 etc) may give better results than ISO-100, 400 etc. This was on a 40D and also a 1Dmk3. Although it seems surprising that the higher ISO might produce better quality images, the suggestion was that this was because 160 was the native ISO on these cameras.
Using 160 instead of 100 isn't going to make much difference to shutter speeds, but I'm wondering if anyone finds this makes a difference to picture quality?
If ISO 160 was base ISO, then ISO 100 would have been called ISO L. So the assumption that ISO 160 is base ISO is wrong. Also, if 160 is base, then ISO 125 would have to be pulled as well, resulting in even lower noise than 160. But that's not the case.
X and a third stop ISO is an exposure that has been pushed by a third. X and two third stop ISO is X+1 which has been pulled a third of a stop. ISO 160, 320, 640 and 1250 are all of the pulled variety which, at the cost of a little dent at the saturation side of the dynamic range, slightly reduce the amount of noise.
Tentacle wrote:
If ISO 160 was base ISO, then ISO 100 would have been called ISO L. So the assumption that ISO 160 is base ISO is wrong. Also, if 160 is base, then ISO 125 would have to be pulled as well, resulting in even lower noise than 160. But that's not the case.
X and a third stop ISO is an exposure that has been pushed by a third. X and two third stop ISO is X+1 which has been pulled a third of a stop. ISO 160, 320, 640 and 1250 are all of the pulled variety which, at the cost of a little dent at the saturation side of the dynamic range, slightly reduce the amount of noise. ...Show more →
Please explain how ISO 160 would be cleaner than ISO 200 by being pulled? Wouldn't ISO 125 be better than ISO 160 since it is really ISO 100 been amped up a bit? Also how does that reduce saturation?
Please explain how ISO 160 would be cleaner than ISO 200 by being pulled? Wouldn't ISO 125 be better than ISO 160 since it is really ISO 100 been amped up a bit? Also how does that reduce saturation?
Pulling an exposure means you overexpose a shot (which moves the whole histogram to the right) which gets exposure compensated downwards (hence 'pulling') to get the exposure right. This downward exposure correction slightly reduces/suppresses the noise in shadow areas. Not by much, but it shows in measurements. And, apparently, it outperforms native ISO 100 and pushed ISO 125.
As counter-intuitive as it may seem, I had the same feeling of disbelief when I read about it, it is real. (The fact that it outperforms pushed ISO 125 isn't all that surprising though.)
Regarding the remark about saturation: I was not talking about color saturation but about photo site saturation. Sorry for the confusion. The process of pulling means overexposing a shot which will decrease the ability of a camera to handle highlights.
Yup, lowest to highest noise for those not wanting to click and scroll....
ISO 160
ISO 100
ISO 200
ISO 320
ISO 125
ISO 250
ISO 400
ISO 640
ISO 500
ISO 800
ISO 1000
ISO 1250
ISO 1600
ISO 3200
On the 30D and 40D, the "in-between" ISOs are simulated in-camera by modifying the Raw data. So for ISO 125 the sensor is set to ISO 100 while metering is set as if at ISO 125 (1/3 Ev underexposure), then the Raw data is multiplied by 1.25. This will increase the noise with no real benefit.
At ISO 160 the sensor is set to ISO 200 while metering is set as if at ISO 160 (1/3 Ev overexposure), then the Raw data is divided by 1.25. This will reduce the noise but at the cost of 1/3 Ev less "highlight headroom" in Raw.
On the 5D, the "in-between" ISOs are achieved by adding a separate amplifier in the analog side, set to 1.25x or 1.6x. This amplifier adds noise. The 1.25x amp setting gives noise results almost as high as the next "full" ISO, while the 1.6x amp setting is noisier than at the next "full" ISO.
So on the 30D/40D, there is no reason to use ISO 125 or its multiples, and ISO 160 is mainly of interest to JPEG shooters. For Raw shooters ISO 160 delivers 1/3 stop less highlight headroom. If you're using ISO 160 along with Expose (to the) Right you'd have to dial in -1/3 Ev of exposure compensation so it accomplishes nothing except to reduce the total number of Raw levels available by about 20%.
On the 5D, there is no reason to use ISO 160 or its multiples, and ISO 125 and its multiples are almost as noisy as going to the next "full" ISO (200 or its multiples), without the benefits of the higher ISO.
On the 5D, the "in-between" ISOs are achieved by adding a separate amplifier in the analog side, set to 1.25x or 1.6x. This amplifier adds noise. The 1.25x amp setting gives noise results almost as high as the next "full" ISO, while the 1.6x amp setting is noisier than at the next "full" ISO.
[...]
Wrong conclusion. The 5D simply pushes both the 1/3rd and 2/3rd stop broken ISO values. It does not use analogue sensor gain for the in-between steps because if that were the case then the noise profile over the whole ISO scale would be continuous. Now it shows dips at 'native' or full-stop ISO values.
Thanks for the info. ISO-320 seems to give noticably less noise on my 40D than ISO-400, and now I keep it set there for general shooting. In good light, or for critical pictures, I've been reducing it to 160 rather than 100, and when I need a higher shutter speed increasing to 640. In lighting where 640 isn't enough I'll generally move to 1600.
It's interesting to see the graph showing how this works, and how things are different with the 5D.
Am I right in thinking that the ISO 160 / 320 settings are equally valid for both raw and jpg shooting on the 40D (I mostly shoot jpegs).
Are the 40D settings also recommended for the 1Dmk3?
I also maintain that ISO 100 is Canon's native resolution. 200 for Nikon.
Many older DSLRs need to be shot at ISO 160 to equal Canons ISO 100. These cameras were overrated to make noise profiles look better. Not that this has anything to do with this topic. It's just another place I've heard ISO 160 mentioned.
In reality a tiny bit of noise at 100% doesn't mean anything. Less dynamic range might. I even set up my cameras to do only whole ISO values, so that I quit worring about this stuff.
dcmiller wrote:
I also maintain that ISO 100 is Canon's native resolution. 200 for Nikon.
Many older DSLRs need to be shot at ISO 160 to equal Canons ISO 100. These cameras were overrated to make noise profiles look better. Not that this has anything to do with this topic. It's just another place I've heard ISO 160 mentioned.
Quite the opposite. The older Canon dSLRs are conservative in their ISO rating. Camera-set ISO would actually be a third of a stop more sensitive than ISO standard and still exhibit less noise. This trend stopped after the 350D, 30D and 5D. Nikon dSLRs followed ISO standard, the Fuji S3 Pro was lagging (and really being under sensitive) while the S5 Pro was, just like the older Canons, oversensitive.
Check out the older reviews at DPReview for details.
I have a 30D and I can tell very easily that there is more noise at 400 and 500 ISO as opposed to ISO 640. Im not sure if its parculiar to my camera but it IS the case.
