I stumbled upon a couple of old threads on other forums mostly criticising the 30D shortly after its release because the 1/3-stop increments you can change the ISO in are not 'real' increments, but the image is taken at the lower full stop ISO, and the camera's software then pushes that image, much like the 3200 ISO expansion works, only less drastic in that the pushing is by 1/3 or 2/3 of a stop and not 1 full stop.
My question is whether this works exactly the same way in other Canon bodies that offer this feature like the 5D and 1 series bodies.
I can't comment on most ISOs as I haven't test them thoroughly, but I can say that on both the 30D and the 1D Mk. IIn (perhaps the 5D) the difference between ISO 1250 and 1600 is subtle, yet quite pronounced when applying NR.
Actually, I've seen charts that show that the pulled ISOs (160, 320, 640, 1250) are lower in noise than the full ISOs they are pulled from. It's essentially exposing to the right by a 1/3 stop and pulling it back...which is a good way to avoid noise, though you'll lose a bit of headroom at the top for highlight recovery.
The lesson...don't use 125, 250, 500 and 1000...they have higher noise than the level above them, so if you're at 400 and need a boost, going to 640 is OK, but skip over 500.
Jman13 wrote:
Actually, I've seen charts that show that the pulled ISOs (160, 320, 640, 1250) are lower in noise than the full ISOs they are pulled from. It's essentially exposing to the right by a 1/3 stop and pulling it back...which is a good way to avoid noise, though you'll lose a bit of headroom at the top for highlight recovery.
The lesson...don't use 125, 250, 500 and 1000...they have higher noise than the level above them, so if you're at 400 and need a boost, going to 640 is OK, but skip over 500.
That's true on the 20d, 30d, and 40d, but not totally correct for the 5d.
On the 5d, stick to:
100
200 (same noise as 100)
400 (less noise than 125)
800 (same noise as 320, less noise than 640)
160, 320, and 640 should also probably be skipped, along with the 125, and 250 that you mention. 500 is ok, with lower noise than 640 or 800.
The noise charts that you mention are likely from the same guy that this one is from. This one is for the 5d:
There is more to it than just the noise level, as dynamic range comes into play. I'll track down the links to original posts from the guy that did all the work, John Sheehy...
Dave Jr wrote:
There is more to it than just the noise level, as dynamic range comes into play. I'll track down the links to original posts from the guy that did all the work, John Sheehy...
Edited by Dave Jr on Jan 31, 2008 at 10:39 PM GMT
Exactly Dave. Loss of DR is my main concern and why I posted this message. I have conditioned myself to use the lowest ISO possible at all times (on older cameras), but now some of those lower ISOs are not better to use then a higher one, both for noise (minor issue at low ISOs) and dynamic range (big issue for me.)
aero145, thanks for the confirmation. I almost never use the 1/3rd stop ISOs, so it is a pain to scroll though them. Oh well, hopefully a Canon engineer is reading this (and if they are, make the "print button" customizable to be a mirror lock up, please!).
Harvey Moore wrote:
The 5D can be set for either 1/3 or 1/2 stop increments
How? I might be wrong, but I don't think so. I've been through the manual and the all the custom functions and menus in the camera, I don't see any way to change from 1/3 stop to 1/2 stop.
There is no such thing as half stop ISO values (on Canon DSLRs at least), it's only aperture and shutter speed that be changed in full, half or third stops
I know on the 40D and on the MKIII I turned the 1/3 stop ISO adjustments off via a custom function. I don't beleive that I was able to do it on the 30D, so it probably own't be possible on the 5D either.
It is much nicer to not have to scroll through all of those other ISO settings. I still keep the exposure settings at a 1/3 stop.
Dave Jr wrote:
How? I might be wrong, but I don't think so. I've been through the manual and the all the custom functions and menus in the camera, I don't see any way to change from 1/3 stop to 1/2 stop.
5D Custom Function # 6 is ISO increments (in CF menu).
