| Malcolm_Stewart |
| (Carpal \'Tunnel) |
| 15/06/2008 10:04 |
In-between ISOs, Read Noise and results
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There's an interesting thread over at UK Bird Photographers comparing graphically the noise from, so far, mainly Canon DSLRs. I don't know how the wizardry works, but for those of us keen to have the lowest noise in our images, it seems best to stick to "natural" ISO settings, viz. 100, 200, 400 etc.
| bdr2 |
| (member) |
| 15/06/2008 14:34 |
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Re: In-between ISOs, Read Noise and results
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Yes, but it's only true up to ISO 800. I know John and he's a bit of a wiz at this sort of thing so I have no reason to doubt his word!
| daft_biker |
| (Action Man!) |
| 16/06/2008 09:14 |
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Re: In-between ISOs, Read Noise and results
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I'm not sure what practical purpose this has. Keeping the ISO as low as possible still works for me.
If I need ISO 500 or 640 because 400 isn't enough it's still better than shooting at 800 for example. Would Canon include them in the ISO range by default for any other reason?
| bdr2 |
| (member) |
| 16/06/2008 12:30 |
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Re: In-between ISOs, Read Noise and results
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Andrew,
I think that's the point. What the thread is saying is that ISO 640 actually produces significantly more noise on both the 5D and 1DMkIII than ISO 800 does. In the case of ISO 500, it just has the edge over ISO 800. Above this, then the in-between ISO's seem to work OK - below and they are significantly worse then the next native ISO.
I don't know how this translates to other cameras in Canon's range, or even if it's noticable in real-life images, but it's certainly an interesting effect.
| daft_biker |
| (Action Man!) |
| 16/06/2008 14:30 |
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Re: In-between ISOs, Read Noise and results
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I can't say I've noticed but I do intend on giving it a go on my 40D.
If it does turn out to be the case I think it begs the question as to why Canon include the 'less desirable' ISO settings by default. Another useless gimick? (they must have nicked the idea from Olympus
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| kevin_c |
| (newbie) |
| 16/06/2008 17:42 |
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Re: In-between ISOs, Read Noise and results
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I've heard this comment about the 1/3 stops previously, I can't prove it on my 20D cos it only has full stop selections
The reason they started putting 1/3 stop ISO's on DSLR's is twofold IMO:
1 - to give you the chance of accurately altering exposure using the ISO - if you want a particular shutter speed/aperture combo you effectively have ISO priority.
2 - A sales/marketing ploy to 'give you more' when you purchase xyz model of camera.
| Northerner |
| (enthusiast) |
| 17/06/2008 07:50 |
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Re: In-between ISOs, Read Noise and results
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Interesting. I'd have never thought that this would be the case - I guess it's similar to odd viewing percentages in photoshop (as a very rough analagy?!) being jaggy?
There is a setting in my 40D to not allow selection of these 'in-between' ISO settings and I have that selected by default. IE - when I flick though the ISO I only get 100/200/400... as options.
I agree with kevin though - it's no doubt a marketing ploy to a certain extent.
Graham
| AGW |
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| 17/06/2008 08:00 |
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Re: In-between ISOs, Read Noise and results
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Strikes me as the sort of issue that Canon could address through a firmware upgrade...if people made it a big enough issue...which I would doubt..
Graeme
| beejaybee |
| (Marvin) |
| 17/06/2008 08:53 |
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Re: In-between ISOs, Read Noise and results
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Quote:
There is a setting in my 40D to not allow selection of these 'in-between' ISO settings and I have that selected by default. IE - when I flick though the ISO I only get 100/200/400... as options.
Me too ... not on IQ grounds but on the simple basis that the ISO settings I use most are at the extremes, and setting "ISO speed setting increments" to 1 stop instead of 1/3 stop speeds up the process.
| kevin_c |
| (newbie) |
| 17/06/2008 09:18 |
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Re: In-between ISOs, Read Noise and results
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I come from a film background, and apart from a few odd ISO's (Ilford FP4,'Portra' type films and Kodachrome) I only ever 'think' in terms of 100,200,400,800 ISO etc.
I wouldn't normally think of adjusting the ISO to adjust exposure unless it is obviously wrong for the light.
As I said before, my 20D won't allow me to have anything else - Maybe I'm too set in my ways...
| Benchista |
| (Wich Tyler) |
| 17/06/2008 09:29 |
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Re: In-between ISOs, Read Noise and results
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This story has been knocking around for some time now. Must say I've never really noticed the difference, but as a matter of course I generally stick to "familiar" settings anyway. The only one I regularly use that's not in the normal progression is 1000, as it often adds a little extra flexibility for a lot less noise with the 5D.