hey guys was reading specs and was wondering......

[canon-ball]

I saw that some cameras have an iso that is expandable and go as far as 104,200!


When and how would you use an iso that high?

[btaylor]

Never. I'm of the opinion that it's a marketing ploy by Canon to have a higher potential ISO than Nikon. The images at those ISO's are pretty muchterrible. I've shot a couple of times at ISO 6400 with my 5D MkII and the noise is almost bearable. Any higher than that and it's useless.

[peety3]

I saw that some cameras have an iso that is expandable and go as far as 104,200!


When and how would you use an iso that high?
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Ignoring the reality that those ISO settings aren't suitable for use, it's very simple: it's all about the exposure triangle:


Big apertures mean thin DoF but lots of light, while small apertures mean thick DoF but little light.


Long shutter speeds mean things happen during the shot but lots of light, while short shutter speeds mean stop-action but little light.


High ISOs mean lots of noise but lots of (apparent) light, while low ISOs mean little noise but little (apparent) light.


If you find a shot that you want and let the camera figure aperture/shutter/ISO in full/partial auto, then want to change the artistic outcome of the shot, you'll have to adjust some of the parameters above. If you want to move one or two to the right, you'll have to move one or two to the left to maintain a similar brightness of the resulting shot.


So, if you want thick DoF and motion blur during a night scene, you might need high ISO.

[canon-ball]

yeah that makes sense. I use the t2i and it has an iso expanable upto 12,800....used it once and it was terrible. so when i saw the one for expanable to 104,000 i was just like why? what would be the point.

[Kamelot]

Yeah, these Canon ISO is not suitable higher than 6400. And if we look to Nikon D3S which is response to Canon 1D mark IV, we would see, that 25600 ISO is quite good for usage. But neither 51200 ISO nor 102400 ISO is not usable.


http://www.dpreview.com/reviews/nikond3s/page17.asp


But in my opinion, 6400 ISO is very good! And if you have fast glass (F/2.8 or less), you can control light whatever you want

[neuroanatomist]

It's all relative to how much noise you're willing to tolerate. The upper ('expandable') endof the available ISO range is unavailable by default and needs to be made available via C.Fn for a reason - basically, you shouldn't use them unless you're desperate for light. But useable ISO is also relative. The 'normal' range for the 1DIV is100 - 12800, whereas the 'normal' range for your T2i is 100-6400. Also, as an example, ISO 3200 on 1.3x crop like the 1DIV is going to be less noisy than the same ISO on your T2i, and the same ISO 3200 on a full frame camera like the 5DII will be even cleaner. The high ISO noise performance of your T2i is essentially the same as on my 7D. Personally, I find 1600 to be useable, 3200 to be barely tolerable. (Side note: I'm jealous of the T2i's capability to set a ceiling for the Auto ISO!!). However, ISO 3200 on a 5DII is very useable.