Canon 6D & noise reduction

[Nathaniel]

I note that it is possible to reduce noise "in camera" (P 90 of manual) and I wonder whether any 6d owner has used this facility esp when using auto ISO?

I also, cannot find anywhere in the manual how I can cap the ISO at any given setting so that the ISO does not rise beyond the level set,when using auto ISO.

Many thanks

Nathaniel

[rajjayaraj]

Re: Canon 6D & noise reduction

Nat, my understanding is that it is only useful if sooting in Jpeg, also it slows the buffer speed. I always turned off as i shoot Raw all the time. Raj

[Nathaniel]

Re: Canon 6D & noise reduction

Thanks Raj.I shoot in RAW/Jpeg but for special assignments I am quite happy to shoot in JPEG if the "in house" noise reduction is any help- when using auto ISO.

[S_J_P]

Re: Canon 6D & noise reduction

The 6D offers a variety of techniques, none of which I use for a variety of reasons cited below:

One option is to allow the camera to take a series of four images and composite them into a final JPEG file (so called multi-shot NR), this is of limited value unless you have a static subject, ambient lighting, and a tripod.

A second option is for in-camera software noise-reduction, available in three levels, but this gives nothing which can't be achieved in post-production using Canon's DPP/ Adobe Lightroom, Adobe Photoshop, or any other decent software with a good deal more control. Additionally, high levels of NR can impact adversely on frame-rate as post-processing is applied at the time of the shot (this is particularly noticeable if you're shooting bracketed images where you can wait an age for the final shot to fire).

A third option, Long-Exposure noise reduction, is only for images of 1second or longer and is akin to dark-frame subtraction used by astrophotographers and isn't of any real merit in everyday photography. This technique also doubles the length of each exposure, so a 5 second exposure can only be made every 10 seconds.

Think of Noise Reduction in the same way as you think of exposure, white balance, contrast, sharpness, or any other parameter - you know what you want/need whereas the camera will just apply a predefined algorithm to achieve a basic estimation of what it thinks might be appropriate. Using software in post-production gives you much more control over what you get!

[Nathaniel]

Re: Canon 6D & noise reduction

Thanks Steve. It is quite clear. Pleaes see also comment under 50mm f1.4 lens

[the black fox]

Re: Canon 6D & noise reduction

the other thing you bring up nat is the auto i.s.o in all honesty canons feeble attempt at auto iso needs to be forgotten about and never used ,when i was using nikons there system is far far superior as when you set auto iso it will actually do it properly ,giving a good exposure with just the amount of EXACT iso needed .i.e i used to get readings of figures like 657iso or 853iso etc.proving it was actually working, this also enabled the use of a 300mm f4 lens and 1.7tc comfortably .
something you cannot do with canons dx models

[Riggers]

Re: Canon 6D & noise reduction

the other thing you bring up nat is the auto i.s.o in all honesty canons feeble attempt at auto iso needs to be forgotten about and never used ,when i was using nikons there system is far far superior as when you set auto iso it will actually do it properly ,giving a good exposure with just the amount of EXACT iso needed .i.e i used to get readings of figures like 657iso or 853iso etc.proving it was actually working, this also enabled the use of a 300mm f4 lens and 1.7tc comfortably .
something you cannot do with canons dx models

But does this mean the exposure is better? I've read stories pointing to scientific evidence that there is little or no value in using intermediate ISO values. I can't remember where but I did read it in an article recently.

I have to admit I've used auto ISO on my 6D in manual mode with evaluative metering and been very pleased with the results. It's been really useful in places with constantly changing light.

[MX5]

Re: Canon 6D & noise reduction

But does this mean the exposure is better? I've read stories pointing to scientific evidence that there is little or no value in using intermediate ISO values.

It's to do with how the camera adjusts sensitivity. See below ...

As for Auto-ISO ... I put the case for the defence ...

The discussion on Auto-ISO has opened up an interesting new world to many people. Especially when used in conjunction with M … this to my mind isn’t manual per se but what I’ll call Iv (ISO value, cf Av and Tv) in that shutter speed and aperture stay constant and ISO will change as light changes. With recent cameras, higher ISO settings are much more usable for everyday photography (rather than as an emergency). So using ISO up to some configured upper ISO limit isn’t going to impact quality too much or indeed produce so much noise a photograph is all but unusable.

The following is for a 7D with firmware 2.0.x (you’ll need to check your manual if you are using a different ‘Truly Auto-ISO capable’ camera [Some early implementations of Auto-ISO on Canon and other bodies, weren’t quite what you might expect]).

You can set the ISO increment (the native ISO of the 7D is probably 100-ISO and consequently speeds of 200, 400 et seq are achieved by ‘hardware amplification’ … intermediate speeds are done by a combination of ‘hardware amplification’ and push/pull a 1/3rd if a stop by software (well as far as I can tell). So I set C.Fn1-2=1.

You can limit the high water mark for Auto-ISO using the menu system, say to 800-ISO. But in M you don’t have a Safety feature.

If you have Safety-Shift set (C.Fn1-6=1) this only comes into use if you are in Av or Tv.

So I would meter off grass (or a grey card) and set my base aperture and shutter speed (with 200-ISO set say). Then switch to Auto-ISO.

Exposure compensation still works in Av/Tv with Auto-ISO and Safety Shift … although that does seem a complex solution to a problem to my mind !

PS: Av + Auto-ISO works as follows as best I can tell. It first change shutter speed based on changing light, but as soon as shutter speed would have to drop below 1/(2xfocal-length) (i.e. slower than 1/200s for 100mm), it would then adjust the ISO (It doesn't appear to take IS into consideration when doing its calculations).

PPS: When I was playing with Auto-ISO I noticed one quirk. If you've set C.Fn1-2=1 (whole stop changes in ISO on the 7D) when in Auto-ISO you get third stops ... well so my brief (none scientific) experiment would seem to indicate. I wasn't expecting that!

[Sarawak]

Re: Canon 6D & noise reduction

It's to do with how the camera adjusts sensitivity. See below ...

As for Auto-ISO ... I put the case for the defence ...

The discussion on Auto-ISO has opened up an interesting new world to many people. Especially when used in conjunction with M … this to my mind isn’t manual per se but what I’ll call Iv (ISO value, cf Av and Tv) in that shutter speed and aperture stay constant and ISO will change as light changes. With recent cameras, higher ISO settings are much more usable for everyday photography (rather than as an emergency). So using ISO up to some configured upper ISO limit isn’t going to impact quality too much or indeed produce so much noise a photograph is all but unusable.

The following is for a 7D with firmware 2.0.x (you’ll need to check your manual if you are using a different ‘Truly Auto-ISO capable’ camera [Some early implementations of Auto-ISO on Canon and other bodies, weren’t quite what you might expect]).

You can set the ISO increment (the native ISO of the 7D is probably 100-ISO and consequently speeds of 200, 400 et seq are achieved by ‘hardware amplification’ … intermediate speeds are done by a combination of ‘hardware amplification’ and push/pull a 1/3rd if a stop by software (well as far as I can tell). So I set C.Fn1-2=1.

You can limit the high water mark for Auto-ISO using the menu system, say to 800-ISO. But in M you don’t have a Safety feature.

If you have Safety-Shift set (C.Fn1-6=1) this only comes into use if you are in Av or Tv.

So I would meter off grass (or a grey card) and set my base aperture and shutter speed (with 200-ISO set say). Then switch to Auto-ISO.

Exposure compensation still works in Av/Tv with Auto-ISO and Safety Shift … although that does seem a complex solution to a problem to my mind !

PS: Av + Auto-ISO works as follows as best I can tell. It first change shutter speed based on changing light, but as soon as shutter speed would have to drop below 1/(2xfocal-length) (i.e. slower than 1/200s for 100mm), it would then adjust the ISO (It doesn't appear to take IS into consideration when doing its calculations).

PPS: When I was playing with Auto-ISO I noticed one quirk. If you've set C.Fn1-2=1 (whole stop changes in ISO on the 7D) when in Auto-ISO you get third stops ... well so my brief (none scientific) experiment would seem to indicate. I wasn't expecting that!

That's a very interesting quote there. Could I ask which website it came from. It looks like there could be a source of useful information on other camera bodies as well.

[Nathaniel]

Re: Canon 6D & noise reduction

I am completely LOST here & cannot understand all this (MX5). I'd appreciate a layman's explanation so that I can usefully make notes and adhere to good advice.

[MX5]

Re: Canon 6D & noise reduction

Nat - I'll try (by the way, the text is from a previous submission of mine, so it's none too clear to me just now).

1. There's a notion been doing the internet rounds for a few years about intermediate ISO settings yielding 'more noise' than the nearest whole ISO setting. Let's assume this notion is correct and then postulate a hypothesis. The result that seems to be accepted is that every whole stop (100, 200, 400) is achieved by hardware amplification (much like your stereo amplifies sound ... conceptually anyway). Now if we assume a particular camera has a 'base ISO' of 200 ... then lower and higher values are achieved by attenuation and application respectively. But intermediate values are done in software. That's the kiss of death as we find someone from Canon who is a black belt in sensors and DIGIC says ... well actually this is what really happens ...

2. There's another notion doing the rounds about Auto-ISO when used with Av. That the software applies some logic ... namely as light falls keep reducing shutter speed (but keep Aperture as set and ISO constant) ... when the light falls to such a level that the shutter speed falls below half the accepted safely-hand-hold value (e.g. for a 300mm lens that would be 1/150 in Full Frame terms), then it fixes shutter speed and increases ISO. I'm guessing now (as I haven't checked) but this continues until the upper limit (you set that) of ISO is reached. If light continues falling ... then I'm guessing it will check if safety shift is set ... if it is and it can open the aperture more then it will ... otherwise it will continue using longer shutter speeds ... well that's unchecked by me ... so I'll put it in yellow). Again what I writ was from experiments. It is likely more complex ... I wasn't trying to flowchart the logic of process and procedure but rather try and understand what Auto-ISO would do for me. In particular how it might impact noise as an unintended consequence.

3. Best thing is to play - Just set Auto-ISO (and set the upper and lower limits if you can for a 6D ... I've not checked). Then go and use Av or Tv and see what two values it uses along with the one you set to get the exposure.

Don't know if that's helped (or made it more confusing) ... but with Auto-ISO and Safety on ... then you give yourself a degree of protection if light suddenly changes and you are too engrossed in the subject than the camera I will admit it's saved me a few times ... but don't tell anyone

[Nathaniel]

Re: Canon 6D & noise reduction

Thanks MX5. thats a bit better and the proof of the pudding is how I manage tomorrow afternoon. I am going to play around a bit- much before 3.30pm.

[the black fox]

Re: Canon 6D & noise reduction

as i tried to explain nat ,and its so hard with the written word as it can be mis-construed ,canons auto iso is a complete joke when compared to nikons ,it was one of the main things that kept me with nikon for 3 years (till they brought out the terrible d7100) on the nikon menu you can pick a iso range i.e from 200iso to 3200iso ,set a minimum shutter speed for say birds in flight with a 500mm lens i used 1250th sec .then just set your aperture on the camera f8 for arguments sake and fire away safe in the knowledge that the only variable in exposure will be if you dial in pos or neg compensation .
the iso values given in exif data were NEVER the same ,and definitely not just running on a 400-800-1250 etc scale or even intermediate values they were on exact iso needed scale i.e iso 478 or iso 976 .but the pics always came out properly exposed .
hope this explains my earlier post better

[AndyMulhearn]

Re: Canon 6D & noise reduction

PS: Av + Auto-ISO works as follows as best I can tell. It first change shutter speed based on changing light, but as soon as shutter speed would have to drop below 1/(2xfocal-length) (i.e. slower than 1/200s for 100mm), it would then adjust the ISO (It doesn't appear to take IS into consideration when doing its calculations).

Interesting. I see something slightly different. On my 7D/Sigma 120-400 combo, in Av mode with Auto ISO the camera adjusts the ISO to keep the shutter speed at 1/640 which is 1.6x400.

[Nathaniel]

Re: Canon 6D & noise reduction

I used manual TV 80;manual f8;auto ISO (no cap and no auto noise reduction) & auto WB to take the photos I have posted under people and places "First outing of 50mm f1.4 lens....". The images have come out reasonably well. On one or two images I used the "dropper" in PSE to correct the colour cast but I noticed that sometimes when using the "dropper" the image becomes very bright- to the level of it was "glaring"! I there removed the "dropper" effect so that the images had a pleasing effect.

Having said that I am very pleased with my Canon 6D & the 50mm lens and particularly the high ISO tolerance levels- the noise doesn't show up at all! In one of the images the auto ISO went up to 10,000!