Tag Archives: noise

Commentary, Equipment, Photographic Myths and Platitudes

Photographic Myths and Platitudes — That Sensor Noise is Awful!

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Let’s say you are looking for a new camera. You want to make a smart decision, especially since you are sinking your hard-earned money into the purchase. You sure don’t want to make a mistake and end up with deficient gear. So you do the smart thing — you do some research. You look around on the web, find some articles, and you discover that there is a lot of contradictory information. Some tell you that Product X is wonderful, while others are adamant that Product X is pathetic and that Product Y is far superior. The Product X fans point out that Product Y is deficient in other critical ways by comparison to Product X.

You have some unanswered questions.

I keep hearing that Camera X has terrible noise compared to Camera Y. In fact, I found some photographs that demonstrate how bad this noise is. Why in the world would anyone get Camera X?!

Both sides provide “evidence.” Photographers love evidence, especially evidence of a failure to achieve divine technological perfection, and double-especially when the failure is demonstrated in a brand they don’t own. They get a little testy though, when the “evidence” makes their product look weak! (For a fun detour, look up the term confirmation bias on the web. Also, this is an important time for a reminder that photography is about photographs, not about cameras.)

I want to construct a little story for you based on “evidence.” We’ll start with evidence that makes a particular product (one that I rely on) look particularly bad. But before we start, you need to promise to read the whole thing. I’ll try to make it worthwhile.

OK, I promise to read it all, and with an open mind.

Good. Here we go.

Lots of people are concerned with the related issues of dynamic range (the camera’s ability to record image data from both light and dark sources in a single photograph) and noise (non-image artifacts that are, in a rough sense, sort of like “grain” on film).

I’ll begin with an example of noise in a photograph I made using the the new and very expensive Canon EOS 5Ds R, a 50.6MP full frame DSLR that Canon released recently.

045DsRPushedAbsurdly100PercentCrop
Example #1

Man, that is awful! That 5Ds R obviously produces terrible noise. It is so bad that the photograph is unusable, at least for anything other than an article demonstrating how bad it is! And the color is pathetically bad, too!

Yes. That image looks absolutely horrible!

Astute, critical thinkers are already wondering what went wrong here. Let me explain. Continue reading Photographic Myths and Platitudes — That Sensor Noise is Awful! →

Equipment

The Canon 5Ds R — Dynamic Range Examples

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Updated August 13, 2015 to add a second dynamic range adjustment example.

Ongoing development and refinement of digital camera technology continues to improve cameras and the technical quality of the images they produce. Color accuracy improves, dynamic range expands, sensor resolution increases, AF accuracy gets better, and so on.

The Canon EOS 5Ds and the Canon EOS 5Ds R continue this process. Their most notable feature is the 50.6 megapixel (MP) sensor, currently the highest sensor photo site density available on full frame digital cameras. (Nikon and Sony both produce 36MP sensor cameras using Sony sensors, and Sony has introduced a camera with a 42MP sensor. Note that the differences between 36MP, 42MP, and 50.6MP are less than you might expect.)

When it comes to dynamic range — the ability of the sensor to record a wide range of luminosity levels from very bright to quite dark in a single exposure — Sony is the current champion, and cameras using their sensors have the largest available dynamic range among comparable cameras. (Some MF cameras have more dynamic range capability than any current full frame camera. )

(All current digital cameras capture images with more dynamic range than we can display on monitors or in prints — the display media cannot keep up with the capture technology. Consequently, the primary advantage of greater dynamic range comes in post-production, where the photographer will find more useful scene data in darker areas that can be “pushed” or otherwise recovered while maintaining useful image quality.)

If you can get more dynamic range without giving up anything else, there is no reason not to have it. In marginal situations, that extra bit of dynamic range might enable you to get a bit more image data in a single exposure, while a photographer with a camera providing less dynamic range is a bit more likely to have to use exposure bracketing or HDR techniques (which combine multiple images in post-production), use a graduated neutral density filter, or possibly find ways to suppress noise in shadow areas of scenes with very wide dynamic range. That said, all current high quality digital cameras capture a wide dynamic range — much larger, for example, that was possible with typical film media. (Note, however, that no currently available full frame camera can capture in a single exposure the largest dynamic range scenes that you may encounter.)

With all of that in mind, I thought I’d share a couple examples of files from the Canon 5Ds R that have been pushed quite a bit. Continue reading The Canon 5Ds R — Dynamic Range Examples →

Equipment, Reviews, Tests

Looking at Canon 5Ds Raw Files: Noise and Dynamic Range

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(Note: The images were not included in the original post, which instead included text links only. The images are now part of the post.)

I just took a break and had time to play with a Canon 5Ds raw file that I found on the web. (Anyone wanting to look at files from the 5Ds should head on over to that link right now — there are something like 90+ files to look at.) It was made with the 5Ds at ISO 100, f/8, 1/400 second. It isn’t clear what lens was used, but it appears that it could have been either the 50mm f/1.8 STM lens or the 24-70mm f/2.8 II.

I opened the file in ACR. I made no adjustments to curves, color, etc. I let ACR automatically correct for CA. Default ACR sharpening used at 15 with masking at 50.

I brought the converted file into Photoshop as a smart object to allow for non-destructive re-editing in Adobe Camera Raw (ACR). I confirmed that shadow areas along the waterline of the boats have luminosity values of 0 — I did this by checking the Lab color representation and watching the L value, which hits 0 in several spots. The general area is shown by the rectangle in the following image: Continue reading Looking at Canon 5Ds Raw Files: Noise and Dynamic Range →

Commentary, Equipment, Post-processing Workflow, Technique

Post-Processing: A Shadow Recovery Example

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(In another forum someone asked a question – actually, more like posed a challenge – related to how much usable detail and quality could be extracted from a raw file that contained areas of very low luminosity, as could happen with a badly underexposed image or with an image of a scene with a very large dynamic range. Since I went to the work of responding and illustrating my response, I figured that I might as well share it here, too. With minor revisions, here it is.)

First, I actually have a “real” version of this photograph in which highlights were slightly blown, but which I preferred to use since I could bring them back in post and get a bit more shadow detail to start with. (It looks a bit bright to me as an on-screen jpg, but it makes a fine print.) That photograph ended up looking like this:

Kolob Canyon, Morning - Morning light slants over the top of sandstone cliffs above early autumn foliage in Kolob Canyon, Zion National Park
Morning light slants over the top of sandstone cliffs above early autumn foliage in Kolob Canyon, Zion National Park

This photograph and the other I’ll move to below were both shot from a tripod with a Canon EOS 5D Mark II at ISO 100 using the Canon EF 24-105mm f/4L IS at f/16. While the “keeper” used for the photograph above had a 1/4 second exposure, the example I’ll use below was shot at 1/30 second.

The exposure challenge in this scene was the very large dynamic range between the bright spot of sky at the head of the canyon and the much darker colorful foliage in relatively deep shadow in the foreground. Exposing for optimal quality in the foreground would completely blow out the sky, while exposing for the sky would necessarily grossly underexpose the foreground.

I originally thought that I might like to have four bracketed exposures in case that would let me produce a better final image via layer blending, but it turned out to be unnecessary and the final image (as shown above) has a single source file with no blending. However, this means that I still happen to have one very badly underexposed (by three stops) version at 1/30 second which I’ll use here as the starting point for what I plan to illustrate in this post. Follow along with me and see what I can do with the very underexposed version of the file… Continue reading Post-Processing: A Shadow Recovery Example →