High ISO performance

There was a time when Canon was the only game in town when it came to the high ISO space. When I was a Nikon shooter (back in the age old D200 days) I would look upon the smooth IS0 1600 images of the Canon 20D with envy. That Canon dominance was further extended with the full frame sensor of the 5D, which along with Canon’s lens selection, eventually persuaded me to switch brands.

Canon’s reign as the high ISO champ came to an end with the release of Nikon’s D3 – the first time 5 digit ISO values got thrown around. Although Canon had the 1D Mark III which for most intents and purposes was a worthy competitor to the D3 up ISO 3200 and 6400 (a much under reported fact), the angry mob of pixel peepers wanted more from Canon.

So Canon countered with the 5D Mark II. Not only would it increase the megapixels from its predecessor, the 5D, it would promise to improve the high ISO performance at the same time.

There are dozen’s of reviews out on the web already which show high ISO performance of Nikon vs Canon vs Sony vs etc… so don’t expect me to add much to that in the way of side by side examples. However, no diary on the Canon 5D Mark II could be complete without mentioning high ISO performance from a photographer’s perspective, so I’ll chip in with some thoughts of my own here.

First of all, I will say one thing – the issue of noise gets misrepresented when it comes to photography. The truth is, noise often doesn’t ruin an image. Some of my favourite shots are littered with those noisy pixels and in fact, some of the greatest shots of all time are taken with immensely grainy ISO 1600 or 3200 film. The recent obsession with noise free images is overdone… However, that doesn’t mean I don’t care about high ISO performance at all. On the contrary, poor ISO performance has decimated many a would be great image of my own and when shooting some subjects (e.g. low light sports photography), it’s one of the most critical aspects of my decision making.

But it’s often not so much the noise itself that’s the problem. The real issue is what actually happens to the image at high ISO’s. When a sensor is unable to handle low light properly, the real issues that plague images are typically one or more of the following:

• Contrast is reduced, leaving blacks lacking punch
• Colours get distorted. Vibrant colours fade, blues become purple, etc
• Dynamic range is ravaged – leaving images washed out with either blown out whites or shadows everywhere
• Detail is destroyed, often by overzealous post processing trying to reduce the noise content and leaving that smudgy, watercolour effect

For me, all this comes back to the point that high ISO performance is quite subjective and as a result, like many other photographic aspects, hard to measure. However from a practical perspective, after a couple of weeks of using the 5D Mark II I have formed my initial conclusion. I’ll get to that in a second. First I wanted to share a few images to illustrate the performance at the high end.

Samples

These are all a night scene in Seattle – chosen as night shots show up noise the most. I shot these in manual mode to ensure an accurate exposure and a fair comparison. Everything shot in RAW, then with noise reduction applied in DPP and finally converted to JPG for resizing / posting. No processing done otherwise.

All images are shot with Canon 135mm L f/2 (wide open). All shots are at F2 which will affect sharpness but I’m using the 135 which is one of Canon’s sharpest lenses so this offsets this somewhat.

I haven’t included the ISO 1600 because honestly, it’s so good it doesn’t warrant a critique. So diving straight in, ISO 3200.

 

21 MP RAW – ISO 3200

ISO 3200. 1/40s

 

100% crop, Noise Reduction set to Low:

At NR set to Low, a lot of detail and colour is still being retained in the Space Needle. Edges are sharp and well defined, highlights are maintained and shadows in the background building are even. Of course, noise is still apparent and visible but this is totally acceptable. This performance allows for significant cropping or alternatively for very large prints with no discernable drop off in quality. Note that despite the excellent performance, I don’t feel confident enough at this ISO to shoot liberally with no regard for exposure, etc. Exposing the image correctly is important as although DR is good, it’s not going to be as good as a lower ISO image so latitude for mistakes or extracting DR through dodging / burning will definitely be less.

 

21 MP RAW – ISO 6400

ISO 6400, 1/80s, Low NR

 

100% crop, Noise Reduction set to Low:

Moving right along, we now see the same scene in ISO 6400. This is with NR still set to low and you can see a significant amount of noise has now crept in. Remember that night scenes are typically the most challenging scenes for high ISO performance (much more so than studio samples). Even so, the amount of noise isn’t intolerable. but the degradation of the blacks is now borderline. There is also a mild banding effect going on in the sky. This will start to show up in prints and even in web resolution images also. However, detail is still excellent and so clearly there is room for a greater degree of NR – which we’ll look at now.

ISO 6400, 1/80s, Medium NR

100% crop, Noise Reduction set to Medium:

Here is a much more pleasing result. I think the level of detail captured is still significant. I’m actually very pleased with this result. This will definitely be fine as a large print and will even provide a small amount of room for additional processing. The practical beauty of this is that with a telephoto lens of 135mm you really need at least 1/80s to effectively handhold a shot. By being able to shoot at ISO 6400, that’s exactly what I was able to get. Although I’m not actually a huge fan of this kind of the photography, the ability to be able to perform night scene citiscapes with a telephoto while handheld is pretty remarkable.

21 MP RAW – ISO 12800

ISO 12800, 1/160s

100% crop, Noise Reduction set to High:

Night scenes at ISO 12800 clearly surpass the capabilities of the sensor. I am sure this ISO level is suitable for some types of photography but it should be used only when there is really very little choice. Had I shot a scene of building in good / bright light, this would look quite different – but then there would be little point as there would be rarely a case when a situation would require that.

I haven’t even bothered to include ISO 25600 – again, only for absolute must cases.

More Samples in lower resolution

One technique for reducing noise is to decrease the size of an image – either in camera or through post processing. After all, do we always really need 21MP? What about the other excellent performing high ISO cameras (e.g. Nikon D700, Canon 1D Mark III) – they have less pixel density and therefore an inherent advantage when it comes to high ISO shooting. So doesn’t it make sense to try to reduce the image size to narrow the gap as it were… It does – and lets revisit ISO 6400 with that in mind.

10 MP RAW – ISO 6400

This shot is the same 6400 image that was shown earlier – but resized in Photoshop (using standard bicubuic resizing) to approx 10 MP.

 

Now, this is a different exposure (same shutter speed / aperture / iso 6400), but taken using sRAW in the camera

How do these compare? Well, contrasted to the 21MP images, there is definitely less noise. Not a huge amount – in a completely non scientific measure I’d say we’re talking 10 – 20% or something like that … but still significant enough to be able to notice. I actually slightly prefer the noise profile of the SRAW shot but that’s purely a matter of taste.

What’s the point and benefit of all this? Well a couple of things.

• First of all if you want to look at 100% crops all day and prefer seeing less noise, shoot SRAW.
• Secondly, if you don’t fancy the huge files that come out of the camera, you again have the SRAW choice
• Finally, if you want to capture the full 21MP sizes but will print in a smaller format, know that resizing gives you similar advantages to if you had shot in lower resolution in the first place

 

Another real world example

Another real world example is the following. This again is the 135mm f/2 shot wide open at ISO 6400. This is under tungsten lighting with the image being captured in SRAW (10 MP).

The high ISO speed means that I can still shoot telephoto under indoor lighting (it’s handheld at 1/50s), again something that is impossible with slower ISO speeds Now out of the difficulties of a night time scene you can see the full capabilities of the ISO 6400 setting – excellent amounts of detail retention while colour / contrst / DR are all excellent for this setting.

 

Comparisons to other cameras and a couple of conclusions

As I mentioned previously, a lot of emphasis in reviews is usually placed on high ISO performance between camera brands, or in the 5D Mark II’s case, between the 12MP Nikon D700, the 24MP Nikon D3X and the 21MP Sony A900.

Generally speaking, you’ll find most conclusions to be along the following lines:

• The Canon 5D Mark II resolves more detail than the D700 but slightly worse high ISO performance
• The Canon 5D Mark II resolves less detail than the Sony A900 but has better high ISO performance

Assuming these statements to be correct (and they are from what i have seen) a reader will likely conclude the 5D Mark II gives either the best of both worlds, or the worst. I saw one write up which concluded the latter but my opinion is the opposite. As a photographer, one of the most important things a camera can give you is choice / flexibility and that’s exactly what this middle ground provides. The 5D gives options – the ability to capture huge 21MP files for excellent resolution… or to sacrifice some detail with heavier noise reduction for better high ISO performance… or to shoot in SRAW in the first place for a lower noise profile. No other camera in that list can provide quite the same choice.

Overall however, its somewhat pointless to compare cameras pixel for pixel. For one, each manufacturer approaches photography from a very different perspective. Secondly, the system (i.e. camera + lenses + flash) is far more important than any single component by itself. The fact that Canon offers a 35mm f/1.4 which can shoot at an entire stop faster than the Nikon 35mm f/2.0 means that Canon could have an entire one stop advantage at this focal length when it comes to low light. Conversely, Nikon have a 12-24mm f/2.8 which Canon does not currently compete with. Which is better? You need to decide for yourself but when the performance is this close to call, you won’t find the answer in an individual pixel.

As a practical set of guidelines, here’s how I deal with the various ISO levels in the real world:

• ISO 100 – 800. This is the new sweet spot range. A photographer is free to shoot in this ISO range with almost no concern for noise, loss of DR, etc. For all intents and purposes, these levels are noise free.
• ISO 1600. I now shoot at this ISO level more than I ever have before. It is going to become one of the most multi purpose ISO levels for me – especially for sports. It’s also the last ISO level where you can use liberally for most situations before starting to worry about image quality. Still leaves room for working the image in post (more on this here.
• ISO 3200. Exceptional quality for the ISO level but you need to use with caution as you have less latitude for exposure mistakes and also less ability to process afterwards. Need to start thinking about noise reduction in post processing. To put this in perspective, I have several sports shots taken at ISO 2000 images from the 1D Mark III which were printed for high end commercial purposes to 30” x 20” and looked fantastic. I expect the same from the 5D Mark II in this 1600 – 3200 range.
• ISO 6400. The last real level where you can still get good image quality. Can be used but exposure is even more important. Consider using NR at medium – high and potentially shooting in SRAW.

So my conclusions are really only about the Canon system. In short, it offers better than Canon 5D high ISO performance while shooting with a full 9 megapixel advantage. In fact, it is just about on par with Canon 1D Mark III, Canon’s former low light champion and and matches / exceeds it when shooting in SRAW (or resizing images for 10MP for a fair comparison). In my opinion, this is the best high ISO camera Canon have made yet.