ISO and Noise?

[Dave_S]

In your experience, how far can you 'push' the ISO on an EOS 7D, before 'noise' starts to become intrusive?

My guess would put ISO 800 as the upper limit.

Dave

[Woolley]

Re: ISO and Noise?

Depends on what I'm shooting. I've shot stage shows happily at 1600 and occasionally at 3200 without significant problems as well as night time holiday shots. The key seems to be artificial light, it's not so good if I accidentally forget to reset it and take some in daylight the next day.

[Dave_S]

Re: ISO and Noise?

I'm guessing that might be a case of low light conditions resulting in the noise not being too visible.

Of course it will be there, as you can't increase ISO without increasing the noise, and high temperatures will also increase the noise figure.

With astro-imaging cameras (not DSLRs), the sensor is typically cooled with a Peltier Cooler, to -20 to -30 below ambient, , to minimise the noise. Not really practical in a DSLR.

Dave

[Les McLean]

Re: ISO and Noise?

Agree with Woolley, I'm happy at 1600 and occasionally at 3200, for me, if you don't nail the exposure, then shadow detail can be noisy.

[Trevoreast]

Re: ISO and Noise?

I agree with Wooley and Les on the numbers, it's lot to do with exposure and other variables.

That's probably the reason why camera manufacturers aviod using terms like noise free images up to X iso value.

People on forums use the phrase "noise free images at X iso", it must be so confusing and ultimatley dissapointing for people who don't know the reality.

Trev

[briansquibb]

Re: ISO and Noise?

I would say iso 1600 is achievable without significant noise - particularly if you expose to the right.

[Woolley]

Re: ISO and Noise?

ISO 3200, f/1.8, 1/125. 7D+50mm 1.4



Yes, there's some noise, but well within the bounds of acceptable.

[colin C]

Re: ISO and Noise?

Just to emphasise some of the thoughts already expressed:

• Noise is subjective to an extent - what is acceptable to me may be unacceptable to you.

• The more you "Nail" the exposure, the less noise will be evident.

• Use the histogram to expose to the right hand side of the histogram, without clipping the highlights.

• Keep post processing to a minimum. The more you are tempted to move the sliders, the greater effect on enhancing noise.

• Only sharpen what you need to. The main subject usually has lots of detail, so will take some sharpening. Large areas of plain colour will show noise more readily, so dont sharpen. Just select what you want sharpened and leave the rest.

• Digital noise is split into two elements: Luminence and Chrominence. Luminence is the size of each piece of noise and chrominence is the colour of each piece of noise - Red/Green in shadow areas and Magenta/Cyan in lighter areas. In general, most people can live with some Luminence, but Chrominence tends to be the more unacceptable. Using noise reduction just to reduce the Chrominence can often do the trick. If you need to reduce both elements, there will be some softening of the image, so as with sharpening, select all of the image except the main subject and just use noise reduction in the selected area.

Taking all the above into consideration, ISO 1600 shouldn't be a problem for the majority of subjects and for some you could use ISO 3200.

Colin

[JaKS_Foto]

Re: ISO and Noise?

Just to emphasise some of the thoughts already expressed:

• Noise is subjective to an extent - what is acceptable to me may be unacceptable to you.

• The more you "Nail" the exposure, the less noise will be evident.

• Use the histogram to expose to the right hand side of the histogram, without clipping the highlights.

• Keep post processing to a minimum. The more you are tempted to move the sliders, the greater effect on enhancing noise.

• Only sharpen what you need to. The main subject usually has lots of detail, so will take some sharpening. Large areas of plain colour will show noise more readily, so dont sharpen. Just select what you want sharpened and leave the rest.

• Digital noise is split into two elements: Luminence and Chrominence. Luminence is the size of each piece of noise and chrominence is the colour of each piece of noise - Red/Green in shadow areas and Magenta/Cyan in lighter areas. In general, most people can live with some Luminence, but Chrominence tends to be the more unacceptable. Using noise reduction just to reduce the Chrominence can often do the trick. If you need to reduce both elements, there will be some softening of the image, so as with sharpening, select all of the image except the main subject and just use noise reduction in the selected area.

Taking all the above into consideration, ISO 1600 shouldn't be a problem for the majority of subjects and for some you could use ISO 3200.

Colin

That is excellent Colin, many thanks.

[Dave_S]

Re: ISO and Noise?

Some excellent input guys, thank you.

Your ISO 3200 image is indeed is indeed acceptableWoolley, producing hand-held result that would have otherwise have required a tripod and longer exposure.

Colin, that is a very informative summary, and yes, noise is a very subjective parameter,

I guess the 'bottom line' is 'suck it and see'.

Incidently, I posted the same question on another Canon forum, and the level of response was very poor compared to here.

Dave

[colin C]

Re: ISO and Noise?

I was just thinking back to my D60 DSLR, which was essentially the same as the later 10D and an ISO above 400 was totally unacceptable. That would probably be comparable to ISO 3200 now.. We have come a long way in a short time.

Colin

[Dave_S]

Re: ISO and Noise?

Technology does indeed move on at a pace, in all 'walks of life, and photographic equipment is no exception.

I remember my Sinclair ZX81 computer, and its staggering just how my current i7 based PC compares with that.

Dave

[Thndr_strck]

Re: ISO and Noise?

Would the size you intend to print/publish the picture you are taking also determine acceptable levels of "noise" ?

[DrJon]

Re: ISO and Noise?

Very much so...

[colin C]

Re: ISO and Noise?

And even how you resize has an effect.

If you do a significant size increase in one step, it can have a dramatic effect on noise. If you increase the size in increments of say 10%, the noise should be less.

Colin