Canon 40D image noise

[StuartR]

I've recently become aware of what appears to be an increase in the level of noise in images taken with my 40D and wondered if any other 40D users on the forum are experiencing the same? Sometimes the noise appears to be "banded" i.e., it has a discernible pattern.

Forget that fact that this image is not particularly good, from the content POV, but it's a good example of the problem. It started life as a RAW file and because I thought the noise was being introduced by my RAW converter, DxO5, I processed this one with Canon's own RAW Image Task.
I didn't apply any processing other than increase exposure by one stop (the original was underexposed by one stop).

The first is the full frame, the second a crop from the image displayed at 100% in CS2. The noise is not quite as obvious in the full frame because I've kept the image size reasonably small for the forum but on the 100% crop it's pretty obvious IMHO.

Any views?

http://dpnow.com/galleries//data//500/40d-noise-ff.jpg

http://dpnow.com/galleries//data//500/40d-noise-100-pc.jpg

[Stephen]

I've recently become aware of what appears to be an increase in the level of noise in images taken with my 40D and wondered if any other 40D users on the forum are experiencing the same? Sometimes the noise appears to be "banded" i.e., it has a discernible pattern.

Forget that fact that this image is not particularly good, from the content POV, but it's a good example of the problem. It started life as a RAW file and because I thought the noise was being introduced by my RAW converter, DxO5, I processed this one with Canon's own RAW Image Task.
I didn't apply any processing other than increase exposure by one stop (the original was underexposed by one stop).

The first is the full frame, the second a crop from the image displayed at 100% in CS2. The noise is not quite as obvious in the full frame because I've kept the image size reasonably small for the forum but on the 100% crop it's pretty obvious IMHO.

Any views?





Hi Stuart, may I ask at what ISO the shot was taken, I can't see the exif data

[StuartR]

Hi Stuart, may I ask at what ISO the shot was taken, I can't see the exif data

Hi Stephen

400 ISO (the camera was on auto ISO)

1/2500 sec
f/6.3
evaluative metering
-1 stop dialled in
neutral picture style

Off home now so I'll be back on-line in an hour or so.

Cheers

Stuart

[Patrick]

Hi Stephen

400 ISO (the camera was on auto ISO)

1/2500 sec
f/6.3
evaluative metering
-1 stop dialled in
neutral picture style

Off home now so I'll be back on-line in an hour or so.

Cheers

Stuart

I experienced this with my Canon 10D when the image was underexposed usually in shadow areas.
I haven't however noticed anything with my 40D, My water canoeist posted a couple or so weeks ago was shot at 800 ISO and not a hint of noise.

Patrick

[StuartR]

I experienced this with my Canon 10D when the image was underexposed usually in shadow areas.
I haven't however noticed anything with my 40D, My water canoeist posted a couple or so weeks ago was shot at 800 ISO and not a hint of noise.

Patrick

That was my experience until recently Patrick, images were remarkably noise free at ISO400.

I'm having to sort some serious PC problems (again!) this evening so the Canon issue will have to take a back seat. Why did I buy a new PC? - because I wanted to spend days getting it to run correctly obviously:mad:

Busman's holiday for me which makes it worse :\ I'm going to have to do a restore tomorrow and start again I think. Wonder if it was Vista SP1?

Should have bought a MAC - nearly did!

[StuartR]

<touch wood> Looks like going back to a previous restore point has done the trick</touch wood> I suspect one of my external USB drives was the problem so I'll try reinstalling that tonight.

My old PC took so long to process images in DxO5 you could set a batch of 30 or so running and go and mow the lawn. In a quick test before leaving for work this morning, DxO processed 3 images simultaneously in just under 30 seconds! Reckon I can live with that :)

[Patrick]

Busman's holiday for me which makes it worse : I'm going to have to do a restore tomorrow and start again I think. Wonder if it was Vista SP1?

Should have bought a MAC - nearly did!

The Visa SP1 package has not given me any trouble but then again nor has Vista other than installing it as an upgrade over XP, clean is the only way. I do think it gets blamed for all problems much like XP did when it came out first.

Any way back to the 40D, I should do a few exposure tests on the same thing in both poor light and good light and at 400ISO and 800ISO possibly 1600 as well (come to think of it I haven't shot at 1600 yet must give it a go). Running from 3 stops under to correct and try to process them all to match as close as possible.
This should expose any noise problems on the under exposed shots. Excessive noise on the correctly exposed shots could be a camera problem.

Patrick

[StuartR]

The Visa SP1 package has not given me any trouble but then again nor has Vista other than installing it as an upgrade over XP, clean is the only way. I do think it gets blamed for all problems much like XP did when it came out first.

Any way back to the 40D, I should do a few exposure tests on the same thing in both poor light and good light and at 400ISO and 800ISO possibly 1600 as well (come to think of it I haven't shot at 1600 yet must give it a go). Running from 3 stops under to correct and try to process them all to match as close as possible.
This should expose any noise problems on the under exposed shots. Excessive noise on the correctly exposed shots could be a camera problem.

Patrick

I've only got one pic in my gallery shot at 1600 ISO (set by mistake!) and that was taken using my 350D so I'd expect the 40D to be better. A usable shot I thought (good colour test too :D)

http://dpnow.com/galleries//data//500/thumbs/IMG_6899_DXO_1.jpg (http://dpnow.com/galleries//data//500/IMG_6899_DXO_1.jpg)

I'll try and do some tests this weekend to determine if it's me or the camera...it could be either! Most of the shots I'm having a problem with were shot with my new 100-400mm lens but I'm not sure I can see how that could be relevant? I should also get into the habit of setting the ISO manually rather than leaving it on auto - don't think I've ever tried my 40D on ISO100 yet (:o) which should, in theory, give the best results from the noise POV.

I'd expect the camera to be able to handle at least a one stop variance in exposure without introducing noise though and I rarely compensate more than that. One thing I have noticed is that if the power switch is fully on it's easy to nudge the thumb-wheel and adjust exposure without realising you've done it. It's also easy to forget to take exposure compensation off once set.

[Patrick]

I've only got one pic in my gallery shot at 1600 ISO (set by mistake!) and that was taken using my 350D so I'd expect the 40D to be better. A usable shot I thought (good colour test too :D)

http://dpnow.com/galleries//data//500/thumbs/IMG_6899_DXO_1.jpg (http://dpnow.com/galleries//data//500/IMG_6899_DXO_1.jpg)

I'll try and do some tests this weekend to determine if it's me or the camera...it could be either! Most of the shots I'm having a problem with were shot with my new 100-400mm lens but I'm not sure I can see how that could be relevant? I should also get into the habit of setting the ISO manually rather than leaving it on auto - don't think I've ever tried my 40D on ISO100 yet (:o) which should, in theory, give the best results from the noise POV.

I'd expect the camera to be able to handle at least a one stop variance in exposure without introducing noise though and I rarely compensate more than that. One thing I have noticed is that if the power switch is fully on it's easy to nudge the thumb-wheel and adjust exposure without realising you've done it. It's also easy to forget to take exposure compensation off once set.

I must confess I have never used auto ISO and can see no good reason to do so, much prefer to make the selection myself.

Under exposure I suspect will be more of an issue at the high ISO levels.
After all the sensors sensitivity doesn't actually change the electronic signal is simply amplified to represent extra sensitivity.

Patrick

[ash]

Hi Stephen

400 ISO (the camera was on auto ISO)

1/2500 sec
f/6.3
evaluative metering
-1 stop dialled in
neutral picture style

Off home now so I'll be back on-line in an hour or so.

Cheers

Stuart


Seems yet again another flaw of the dreaded 'AUTO' even if you was shooting in manual and you chose the shutter and aperture, at 2500/sec why did the auto iso choose 400?
Very strange.
Dont even start me off on why you were using 2500/sec shutter speed anyway:eek:
What was it a supergoose travelling at warp speed*LOL

[StuartR]

Seems yet again another flaw of the dreaded 'AUTO' even if you was shooting in manual and you chose the shutter and aperture, at 2500/sec why did the auto iso choose 400?
Very strange.
Dont even start me off on why you were using 2500/sec shutter speed anyway:eek:
What was it a supergoose travelling at warp speed*LOL

No, it was standing still! I wasn't being too serious that day, just "playing" with my new lens (you know what it's like :)) in my lunchtime. IIRC I was trying different apertures on Av. I was also practicing hand holding it because it's a bit of a beast compared to my old 70-300mm, mind you, at 1/2500 sec I could have turned the IS off :D

As to your question, it's a fair one. It was a bright day (obviously) so why didn't it drop down to 100? I've tended to leave it on auto ISO and, now I've looked, by far the majority of my pictures are 400ISO or between 400 and 800 (including those taken before my perceived noise problem). Most peculiar, I'll have to trawl the net on this one and RTM. My son's Lumix lets you lock the ISO upper limit but I'm pretty sure that's not an option on the 40D but, as I said, I'll RTM just in case I missed it.

In the "good ol' film days" you looked at the weather, considered your subject and loaded accordingly - looks like I'll have to re-learn that...it's now set on 100ISO!

[StuartR]

Well it was set at ISO100 but only because I'd got the mode dial on one of the three custom settings (don't know how it got there!). Any other mode and the lowest ISO I can set is 200 although the manual seems to imply that 100 should be available as should "H" (3200 - and I do have the appropriate custom function set to "on") but I can get neither.

I'm obviously doing something stupid, need to RTM again or there's a conflict of settings somewhere - any other 40D users have a view?

I don't use the basic zone settings but will admit to using "P" fairly regularly hence, reading the rules below, ISO400 is the norm on most of my shots when the ISO is set to "AUTO"- the camera will only set a lower ISO on P if overexposure would be the result at ISO400. (this also goes for Av which I guess I'll be using more often on my 100-400mm).

So, for the moment I'll set my ISO manually to 200 which seems to be as low as I can go (I will investigate the custom settings though).

Relevant pages from the manual:

http://dpnow.com/galleries//data//500/40d-manual-0.jpg

http://dpnow.com/galleries//data//500/40d-manual1.jpg

As the noise issue seems to be a relatively new phenomenon for me I wonder if the last firmware update (1.0.8 ) could have anything to do with it? Probably not. I've also found posts on other forums asking about noise problems so I'm not alone, which is heartening - i.e. I'm probably not imagining it :D

[Patrick]

Well it was set at ISO100 but only because I'd got the mode dial on one of the three custom settings (don't know how it got there!). Any other mode and the lowest ISO I can set is 200 although the manual seems to imply that 100 should be available as should "H" (3200 - and I do have the appropriate custom function set to "on") but I can get neither.

I'm obviously doing something stupid, need to RTM again or there's a conflict of settings somewhere - any other 40D users have a view?

I don't use the basic zone settings but will admit to using "P" fairly regularly hence, reading the rules below, ISO400 is the norm on most of my shots when the ISO is set to "AUTO"- the camera will only set a lower ISO on P if overexposure would be the result at ISO400. (this also goes for Av which I guess I'll be using more often on my 100-400mm).

So, for the moment I'll set my ISO manually to 200 which seems to be as low as I can go (I will investigate the custom settings though).

Relevant pages from the manual:

http://dpnow.com/galleries//data//500/40d-manual-0.jpg

http://dpnow.com/galleries//data//500/40d-manual1.jpg

As the noise issue seems to be a relatively new phenomenon for me I wonder if the last firmware update (1.0.8 ) could have anything to do with it? Probably not. I've also found posts on other forums asking about noise problems so I'm not alone, which is heartening - i.e. I'm probably not imagining it :D

Ok my advise is forget the creative zone altogether, anything below the green square on the control dial. I personally see them as an insult to any self respecting photographer.;)
I set my camera to aperture priority most of the time Av, and select the aperture suitable for the scene f4 to f5.6 perhaps sometimes f8 for portraiture, f11 to f16 for most landscapes, and so forth. The metering system will then set a shutter speed. For action shots set to shutter priority Tv and the metering system will decide on an aperture. If a lower or higher ISO are required then set that manually yourself to suite the conditions, 100 or 200 by default for general photography, then in low light or when fast shutter speeds (action) are required 400 , 800 or even 1600 but you make the choice. Ensure correct exposure I find with the Canon in bright sunlight overexposes so I underexpose between half and a full stop. in dull and flat conditions I accept the reading. Under exposed images will be prone to unwelcome noise far more than correctly exposed images.
Believe me you can shoot almost anything using these guide lines, the rest is sales gimmick and they teach you nothing about picture taking.
The name of the game is controls by the photographer,:cool: and not by the camera.:eek:

Patrick

[StuartR]

Ok my advise is forget the creative zone altogether, anything below the green square on the control dial. I personally see them as an insult to any self respecting photographer.;)
I set my camera to aperture priority most of the time Av, and select the aperture suitable for the scene f4 to f5.6 perhaps sometimes f8 for portraiture, f11 to f16 for most landscapes, and so forth. The metering system will then set a shutter speed. For action shots set to shutter priority Tv and the metering system will decide on an aperture. If a lower or higher ISO are required then set that manually yourself to suite the conditions, 100 or 200 by default for general photography, then in low light or when fast shutter speeds (action) are required 400 , 800 or even 1600 but you make the choice. Ensure correct exposure I find with the Canon in bright sunlight overexposes so I underexpose between half and a full stop. in dull and flat conditions I accept the reading. Under exposed images will be prone to unwelcome noise far more than correctly exposed images.
Believe me you can shoot almost anything using these guide lines, the rest is sales gimmick and they teach you nothing about picture taking.
The name of the game is controls by the photographer,:cool: and not by the camera.:eek:

Patrick

Hi Patrick

The only settings I normally use are P and Av, sometimes A-DEP. IIRC I've never used the creative settings - I've been behind a camera long enough (just over 40 years) to understand the basics ;) despite the use of P and auto ISO. I also use the "underexpose by one stop" rule for some landscapes following advice that I think came from this forum - probably either Stephen or yourself - and this does seem to work well - I certainly get better exposed skies in most cases.

However, I find "P" normally works quite well so I'm happy to go with it and drop back to Av or, very rarely ,Tv (I don't seem to shoot many subjects where shutter speed is the primary factor) or even M as necessary. The trouble with P of course is that you can (well I do) lose track of what aperture & shutter speed combination the camera is setting and therefore get some, on the face of it, odd results - like my duck shot at the top of the post. The other issue with P, now that I've RTM, is that auto ISO has a lower limit of 400 which is why the exposure ended up as it did.

I've currently set my ISO to 200 which appears to be the lowest I can set - if you can set 100 on your 40D I'd like to understand why I can't :confused: (except in the 3 user modes as mentioned earlier).

Cheers

Stuart

[Stephen]

I'm not too impressed with this Auto ISO malarkey Stuart, it seems that in most cases it wants to select ISO 400 as a minimum unless overexposure is going to occur.

I find it hard to believe however that you can't select ISO 100 manually on the 40D The 2 forerunners to it that i've owned all did it OK which is more than could be said for equiv Nikons which had a minimum ISO of 200

[StuartR]

I'm not too impressed with this Auto ISO malarkey Stuart, it seems that in most cases it wants to select ISO 400 as a minimum unless overexposure is going to occur.

I find it hard to believe however that you can't select ISO 100 manually on the 40D The 2 forerunners to it that I've owned all did it OK which is more than could be said for equiv Nikons which had a minimum ISO of 200

Seeing as most of my day job is about writing software to automate processes (albeit not in photography but a LOT more complex than the ISO, shutter speed, aperture relationship here) I'm going to have to say that I'm generally pro this automation malarkey :D

I mean, in theory, automated ISO settings should be easy to program, probably far easier than face recognition for example, which is becoming increasingly more common on compact cameras. However Canon don't seem to have done a brilliant job on the 40D - unless ISO100 & 200 are no better than 400 of course!

It should be simple to automate the ISO AND give photographers a number of parameterisation options - like setting the minimum and / or maximum limits or full manual.

I'll check my old 350D tomorrow as I'm with my brother who bought it (I have to look at his 1,500 pictures taken with it in Canada recently :eek:). I can't remember what the ISO options were on that.

I really can't set 100 on my 40D although the manual clearly states I should be able to..

[StuartR]

It came to me all of a sudden about half an hour ago from some dark corner of my mind whilst eating dinner. Although quite how chicken and ISO met in my mind I'm not sure...

There's a custom function "Highlight Tone Priority" on the 40D and if you switch it on then ISO100 is no longer available. Turn it off and it is.

So there you have it, mystery solved. I was right and wrong at the same time.

Now, is it better to leave highlight tone priority on and be limited to ISO200 or switch it off to get ISO100? Answers on a postcard please....

[Stephen]

It came to me all of a sudden about half an hour ago from some dark corner of my mind whilst eating dinner. Although quite how chicken and ISO met in my mind I'm not sure...

There's a custom function "Highlight Tone Priority" on the 40D and if you switch it on then ISO100 is no longer available. Turn it off and it is.

So there you have it, mystery solved. I was right and wrong at the same time.

Now, is it better to leave highlight tone priority on and be limited to ISO200 or switch it off to get ISO100? Answers on a postcard please....

Mmmm I'm not sure I understand the purpose of this function :confused:
Glad you sorted it out though Stuart, I'd never have come up with that solution *LOL

[Patrick]

Hi Patrick

The only settings I normally use are P and Av, sometimes A-DEP. IIRC I've never used the creative settings - I've been behind a camera long enough (just over 40 years) to understand the basics ;) despite the use of P and auto ISO. I also use the "underexpose by one stop" rule for some landscapes following advice that I think came from this forum - probably either Stephen or yourself - and this does seem to work well - I certainly get better exposed skies in most cases.

However, I find "P" normally works quite well so I'm happy to go with it and drop back to Av or, very rarely ,Tv (I don't seem to shoot many subjects where shutter speed is the primary factor) or even M as necessary. The trouble with P of course is that you can (well I do) lose track of what aperture & shutter speed combination the camera is setting and therefore get some, on the face of it, odd results - like my duck shot at the top of the post. The other issue with P, now that I've RTM, is that auto ISO has a lower limit of 400 which is why the exposure ended up as it did.

I've currently set my ISO to 200 which appears to be the lowest I can set - if you can set 100 on your 40D I'd like to understand why I can't :confused: (except in the 3 user modes as mentioned earlier).

Cheers

Stuart


Sorry if I was trying to teach you to suck eggs Stuart,:o but I do stand by the advice.

It is true to say you have brought my attention to something about the 40D I hadn't noticed and that is 200 ISO is the lowest it will go, the 10D goes down to a 100 but not the 40D. Strange that.:confused:

For Stephens benefit the highlight alert is supposed to extend the dynamic range by up to a stop, I have not used it myself but report say it can lead to some strange results, perhaps one is increased noise. Food for thought and testing Stuart.

Patrick

[StuartR]

Sorry if I was trying to teach you to suck eggs Stuart,:o but I do stand by the advice.

It is true to say you have brought my attention to something about the 40D I hadn't noticed and that is 200 ISO is the lowest it will go, the 10D goes down to a 100 but not the 40D. Strange that.:confused:

For Stephens benefit the highlight alert is supposed to extend the dynamic range by up to a stop, I have not used it myself but report say it can lead to some strange results, perhaps one is increased noise. Food for thought and testing Stuart.

Patrick

Food for though indeed...

No offence taken m8! Nothing wrong with the advice!

I read on some American wedding forums a while back that the Highlight Tone Priority facility is apparently much liked by wedding photographers because it helps with the white dress / black suit exposure issue. Perhaps I'll switch it back on when I next do a wedding :)

Doesn't look like I'll get a chance to do any testing this weekend, we're "down home" in Kent tomorrow but the weather doesn't look good and we have a pretty tight schedule anyway. I'm giving my brother my old 70-300mm IS while we're there though, so I guess he might want to go out for half an hour if the rain stops and we can get a pass from the women-folk :rolleyes:

He lives with a couple of miles of Dover docks and the Castle and either would be a good test subject.