Tag Archives: dynamic

Post-processing Workflow, Software, Technique

What You Get Is Not What You See

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Recently I spent more than a week photographing in a beautiful area of the Sierra Nevada backcountry. A short walk above the spot where we camped was a magical meadow — a place filled with light, grasses still green but starting to turn golden, high elevation trees scattered around the edge of the meadows, and a deep valley separating us from alpine valleys topped by steep granite peaks and ridges with scattered snow fields. At times clouds would float by and add some interest to the blue Sierra Nevada sky.

What I saw

Here is one of several photographs I made in this meadow, with the first example being a small version of a print-ready final interpretation…

Subalpine Meadow, Forest, and Peaks
At the edge of a subalpine meadow, surrounded by forest and high peaks

Here is another version of the photograph, straight out of my raw file conversion program and before I did additional work in Photoshop…

File after raw conversion operations

I think it reflects fairly well what I saw while I stood behind the tripod as light softened by closer clouds spread across the meadow. I’m confident that anyone who had been there with me would agree.

What the camera saw

But that is not what the camera saw. Here is what my captured file looked like before I did my raw conversion post-processing…

RAW file as exposed before conversion processing

Yuck!

This SOOC (“straight out of camera”) image looks pretty bad. The sky is OK, but the meadow is dark and flat-looking, not showing the actual quality of light at all, and the forest appears to be almost completely black.

What’s up here? Am I trying to trick you and present a false version of the scene? Am I an incompetent photographer who completely blew the exposure? Am I trying to “compensate” for a bad exposure by using radical post-processing?

The answer is “none of the above.” Continue reading What You Get Is Not What You See →

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 →

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 →

Technique

Exposure Blending – A Quick Overview

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(This is a slightly modified version of something I wrote as part of a discussion on Google+)

The author of the post that I read before writing this mentions two alternatives for dealing with dynamic range issues in landscape scenes – the use of graduated neutral density (GND) filters or the use of a similarly-named post process technique in Lightroom. (Similar processes are available in other software including Photoshop/ACR.) Another alternative is to use HDR (High Dynamic Range) techniques that allow computer algorithms to combine source images in ways that are not the same as what I describe in this post. I almost always use a different approach, exposure blending, and I’d like to share a few ideas on this topic.

When the scene contains an extremely large dynamic range – a common situation in landscape photography – it is possible to end up with shadow areas that are nearly black and devoid of detail, along with bright areas that are blown out and also completely lack detail. (The latter is especially an issue with digital capture in which overexposed areas can simply become pure white. Film failed more gracefully in this situation.)

One traditional method for dealing with such scenes is to attach various types of graduated neutral density (GND) filters to the front of the lens. These filters include a clear area and an area darkened by a few stops. A typical use might be to position the dark portion over the sky and the clear section over a darker foreground, effectively reducing the dynamic range of the light reaching the sensor by reducing only the brightness of the sky. With film, especially positive transparency film, this was just about the only realistic way to handle the situation in many cases.

A second method is to make a single exposure and use features in Photoshop/ACR, Lightroom, or other software to simulate the effect of the GND, lightening (or darkening) a portion of the photograph. This can often help quite a bit when it comes to balancing out dark and light areas in the image, and the fact is that most savvy landscape photographers do this sort of thing and more in post. But it has its limits. For example, darkening a bright area cannot put detail back in blown out areas, and lightening underexposed shadows can lead to problems with noise and posterization. The bottom line is that this technique works well when the overall range 0f brightness in the scene does not exceed the dynamic range of the camera – here it may be used to adjust the relative levels of the areas – but it does not work well when the dynamic range is actually too great for a single normal exposure.

There is a third method, sometimes called exposure blending, that can often be used when making the exposure. The idea is to make more than one exposure, with each exposure optimized for different parts of the scene by varying shutter speed, and then selectively blend the two exposures during post-production.* Two exposures are sufficient in almost all cases, with one for the shadow detail and the other for highlight detail – though in very complex or wide dynamic range situations more exposures can be used. Continue reading Exposure Blending – A Quick Overview →