Canon 40D High ISO performance

[paulr5604]

I have been trying out the high ISO capabilities of the 40D today aswell as the macro facility on the Tamron 70-300 and I have to say I'm quite impressed. I know its not up to the same standard as the newer models etc.


Exposure 0.006 sec (1/160), Aperture f/8.0, Focal Length 180 mm, ISO Speed 3200


Exposure 0.003 sec (1/320), Aperture f/8.0, Focal Length 180 mm, ISO Speed 1600

Both images have had very little Noise reduction.

[EOS_User]

Re: Canon 40D High ISO performance

Hello Paul;

I always thought the 40D was a superb piece of kit (I wore mine out) and these images demonstrate that IMO...

A little cleaning-up with something like Neat Image or Noise Ninja, and who would know that they weren't taken with latest technology!

Cheers;

Lee

[Paulstw]

Re: Canon 40D High ISO performance

I tend to think of high ISO as something that people tend to get wound up about too often. I think that as long as the subject is exposed properly, in focus and looks good to the eye, there's never going to be an issue. Shown well in your shot.

It's the out of focus, shadow and under exposed areas of an image that tend to exhibit noise and with nearly everyone using Lightroom these days it tends to show more because of that dreaded shadow slider lol.

Two perfectly decent shots

[paulr5604]

Re: Canon 40D High ISO performance

Thanks guys I slightly over exposed these so that I would avoid any major shadow areas and I could bring the exposure back down in photoshop. I only have the NR that is part of CS6. Will have to look into alternatives

[Paulstw]

Re: Canon 40D High ISO performance

Ahh the good old ETTR method. Something I never get a chance to use.

[paulr5604]

Re: Canon 40D High ISO performance

Yeah I read it somewhere else on the internet and thought it made sense seeing as the majority of noise appears in the darker parts of the image. The main reason I wanted to check the High ISO images is down to the wedding I may be photographing in October I just wanted to put my mind at rest about being able to minimise the amount of noise in the image in the camera without having to rely too much on software which takes some of the detail out with the noise. I am always striving to get the exposure right in camera (doesn't always work though). I now feel more at ease with upping the ISO if I need to. Something that I wouldn't have even contemplated with the 400D I used to own.

[Paulstw]

Re: Canon 40D High ISO performance

One thing I worried about with my wedding shots was noise, composition, contrast, good light etc etc till I felt sick. See when I gave the couple the proofs? They were over the moon and did not mention anything about noise or anything and I was at ISO3200 most of the day lol.

I just practised my stuff round about the house. Just floating about with the camera and snapping folk coming out of rooms and stuff to see how I'd react to given situations. Everything happens to fast at a wedding, and you don't get much chance to think about settings or trying something new. You just check the histogram for decent exposure, sharpness and then just gun down every shot like it was your last. It's the planned shots that you can take your time over :) I think you'll be good.

Incidentally I was just asked to do another wedding next year...

[paulr5604]

Re: Canon 40D High ISO performance

One thing I worried about with my wedding shots was noise, composition, contrast, good light etc etc till I felt sick. See when I gave the couple the proofs? They were over the moon and did not mention anything about noise or anything and I was at ISO3200 most of the day lol.

I just practised my stuff round about the house. Just floating about with the camera and snapping folk coming out of rooms and stuff to see how I'd react to given situations. Everything happens to fast at a wedding, and you don't get much chance to think about settings or trying something new. You just check the histogram for decent exposure, sharpness and then just gun down every shot like it was your last. It's the planned shots that you can take your time over :) I think you'll be good.

Incidentally I was just asked to do another wedding next year...

Congrats on getting another wedding for next year was it through the B&G from the wedding you have done?

I starting to feel the same as you about the low light stuff but I know that a fast lens will go some way to helping with this. The formal shots I don't have an issue with. I'm sure that I am worrying about something that I don't need to I will just do as you did and practise practise in low light situations.

[Paulstw]

Re: Canon 40D High ISO performance

See as a saving grace Paul, somehow you just instinctively know what to do. I nearly bailed after about 15mins. I'm so glad I didn't need a number 2 cause I swear even it would have bailed on me at that point but Pauleen (who came with me) just totally settled my mind and I jumped in head first. Before I knew it I was grabbing all sorts of pics. I think you'll do the same. Totally different feeling when you're concentrating on the photography instead of when you need to be home and how upset the wife will be when you do get in lol.

Someone in work asked me to do it. That's three I have no :/ - So much for not wanting to be a wedding guy.

[paulr5604]

Re: Canon 40D High ISO performance

Totally different feeling when you're concentrating on the photography instead of when you need to be home and how upset the wife will be when you do get in lol.

Ooooh can't wait to experience that feeling lol

[Paulstw]

Re: Canon 40D High ISO performance

Ooooh can't wait to experience that feeling lol

Just keep doing the work :)

[S_J_P]

Re: Canon 40D High ISO performance

Congrats on the latest commission Paul(S), I suppose you’ll be in the market for some more glass shortly?

Paul(R), I like your experimentation and I’m most impressed by the 40D’s lack of noise, older cameras aren’t supposed to be that good but you’ve really shown that with a little insight and good technique high ISO shouldn’t be dismissed

I’m not sure whether you’ve read about why ETTR works, but as I’m having a quiet afternoon at work I thought I’d run through the theory, it may be useful to someone!

At normal ISO, the camera sensor’s dynamic range may be around 9-10 stops whereas a typical scene may comprise four-six stops of dynamic-range. Where these four-six stops of DR lie within the sensor’s “DR window” has a huge impact on the resulting image.

If we talk about raw images for the moment (the impact is so much worse for JPEG!), image files are 12-14-bits/pixel depending on the DIGIC processor version, that is equivalent to 2,048 (12-bit) to 8,192 (14-bit) brightness levels per pixel. If I remember correctly the average human eye can only perceive around 100 brightness levels, so everything looks extremely rosy.

However, the way these 2-8k levels are distributed is the problem, the levels are evenly distributed across the entire 9-10 stop dynamic range. This means that for a 14-bit image the brightest stop of the sensor’s dynamic range is given 4,096 levels. The next brightest stop is given 2,048 levels. The third stop 1,024 levels, etc all the way down to the tenth-stop which is allotted a measly 16 levels.

If a photographer exposes to the right (ETTR) so that the image occupies the right (bright) side of the sensor’s dynamic range window, then in a six-stop scene even the darkest tones still have 128 levels available. If he exposes to the left, then the brightest stop has 1,024 levels available, and the sixth stop just 16 levels available.

If we move to a 12-bit camera, then the numbers are 4,096 levels for the brightest stop and 4 levels for the darkest stop, so ETTR gives a minimum of 32 levels for the sixth stop. The worst-case of exposing to the left gives between 256 and 4 levels for each of the six stops.

JPEG at 8-bit is scary! There aren’t sufficient native levels to populate a 10 stop dynamic range, and that’s the reason that raw images can be so readily adjusted to pull-out shadow detail or highlight detail which wasn’t visible on our (usually) 8-bit monitors, there’s so much more information than is readily displayable. JPEG images will often “clip” the extremes of dynamic range, so just eight stops of range are available. With ETTR the brightest stop will have a measly 64 levels available, whilst the sixth stop will be left with just 2 levels! Expose to the left and you’re at 32 to 1 levels.

Why does this matter? Because noise can manifest itself in a variety of guises, and having fewer levels to play-with both increases the amount of quantisation or blockiness in the image (where similarly bright areas are merged into a single level due to the dearth of available levels) and increases the amount of the image which falls below the noise floor. In effect, the lower so-many-levels are prone to be inherently noisy because the camera/sensor’s bias-noise, dark-noise, Poisson-noise, and random-noise, occupy these lower regions where the actual signal is so tenuous. As the signal strength diminishes in these lower levels, so the noise increases as a proportion of the whole, i.e. the signal:noise ratio become poorer. Avoiding using any of these lower levels means that the Signal:Noise ratio remains good, noticeable quantisation is avoided, and the image looks cleaner. Adjusting the exposure of the ETTR image down in post-production to mimic the actual brightness levels originally present will then diminish the noise in proportion to the signal, and whilst quantisation may still manifest itself, the usual colour/luminance noise won’t become noticeable.

The downside of ETTR is that you either need to go to a wider aperture, a slower shutter speed, or a higher ISO. The first two options may not be desirable as it could alter the image in terms of depth of field or motion freezing. The third option will itself increase the noise level by increasing the bias/dark noise. It’s worth experimenting as you are with the various combinations to determine whether the ISO-increase benefits outweigh the detrimental effects.

Phew! I hope I've not made any horrendous boo-boos there, and I hope no-one has nodded off

[CountDavid]

Re: Canon 40D High ISO performance

A very useful summary Steve - again emphasises the benefit of shooting RAW.

David

[paulr5604]

Re: Canon 40D High ISO performance

Thanks for the explanation Steve I kind of understood it .