1. A high dynamic range (high contrast) scene. This means that the image should contain a range of tones from the very brightest to the very darkest, without being under or over-exposed i.e. producing image 'noise' at the darkest end or highlight 'clipping' at the brightest. As noted in the course notes for Exercise 8, a high dynamic range image needs, ideally,
- bright sunlight
- at least one brightly reflecting surface
- an area of deep shadow with a dark surface
High Contrast Image 1
As an example, I took this pre-sunrise shot on a recent holiday in Northern Spain. The un-adjusted Raw image is shown below. ISO was set to 100 (its lowest setting on the Canon 50D) and the noise reduction function set to OFF (its default setting).
The challenge here was to capture the very bright pre-dawn sky whilst showing some detail in the dark foreground. Using a tripod and aperture priority setting the camera settings were as follows. f/11, shutter speed 0.6 secs, ISO 100, AWB and exposure compensation of -1 to eliminate highlight clipping (as shown by the absence of any clipping warning on the camera LCD).
The image was subsequently processed using the Lightroom Raw converter and then Photoshop to give the following image.
The adjustments made were as follows.
In Lightroom - increase Contrast to +86 to make the image punchier, increase Recovery to +63 to help recover any highlight problem, reduce Blacks to zero to give more shadow detail, increase Clarity to +75 to add some sharpness, slight increase of Vibrance to +22 to hep the sky tone and, finally, Sharpening to +50.
In Photoshop, Image>Adjustments>Levels to make the range 12 to 249 with a mid-tone adjustment to 1.04 to slightly lighten them. Finally, I converted the image to sRGB Profile for web posting (as with all photographs for this assignment).
The overall effect has been to give the image more contrast and to bring out some of the detail on the hills. Were I to take the shot again, I think that I would have used a narrower aperture (f/16?) to improve the sharpness on the horizon.
High Contrast Image 2
Another example of a high contrast shot was one taken indoors of a stained glass window, the contrast being between the brightness of the light through the window panels and the dark wood of the window-frames. The photograph was taken in the northern Spanish town of Comillas in a house, El Capricho, designed by Antonio GaudÃ.
The un-adjusted shot from the camera is as follows.
As I used an exposure compensation of -1 indoors the result is a dark image, but without highlight clipping. Other settings were f/11, shutter speed 1/60 secs, ISO 400 (handheld) at 30mm (with 18 - 270mm zoom lens). I used 'Daylight' WB.
The Raw image was adjusted in Lightroom and then Photoshop to give the following result.
The Raw converter adjustments were Contrast to +70, Recovery to +76, Fill Light to +83, Clarity to +66, Vibrance to +36 and Sharpening to +60. I also made a vertical lens distortion correction of - 31 and then cropped the image as shown.
In Photoshop, Image>Adjustment>Levels to slightly adjust the range to 4 - 248 with a mid-tone adjustment to 1.11.
The overall effect produces a much more even image. Perhaps using a higher ISO setting would have been better although I am not convinced.
2. A low-dynamic range (low-contrast, 'flat') scene. This would be a daylight shot but, perhaps, in murky conditions with the subject matter comprising mid-tones so that there are little, if any, of the darkest or brightest tones available to be captured.
Such a shot was taken around the old church in San Vicente de la Barquera in northern Spain. Although it was a sunny day, this side of the church was in shade. The photograph was hand-held (ISO 400), f/11, shutter speed 1/100sec at 32 mm (18-270mm lens). I used a WB setting of 'Shade' and an exposure compensation of -2/3. The histogram indicated that there were very few pixels at the dark end and none anywhere near the bright end.
The un processed image (above) appears very flat compared with the processed image below.
This was achieved by increasing the contrast and using fill-light. The Raw converter settings used were Fill Light + 52, Contrast + 78, Clarity + 61, Vibrance + 22 and Sharpening + 60. In Photoshop, Image>Adjustments>Levels a range of 10 - 183 with midtones at 0.83.
A higher ISO setting could have been used in camera but I was confident of being able to produce a good final image at ISO 400.
3. Low-light conditions which require a high ISO setting.
An example of this is the following image taken on the near-by canal which I offer, not because it results in a good final image, but because of the interesting issues that it raises. The un-processed image is as follows
As can be appreciated by the dark image, the sky was very bright. In order to show some detail in the sky and avoid total 'white-out', I used an ISO of 1250 and focused on the sky before framing the shot. Even with this high ISO, focusing elsewhere in the frame resulted in a complete loss of definition in the sky even after processing in Lightroom and Photoshop. The settings details were f/10, shutter speed 1/4000th sec at 11mm using an 11 - 16mm wide-angle lens, exposure compensation -1 and 'Cloudy' WB setting.
After processing, the resulting image certainly showed plenty of definition in the sky but there was considerable 'noise' in a great part of the frame. Interestingly, this 'noise' was not present when I had taken the same shot (with identical settings) after focusing on the underside of the bridge, rather than the sky. However, in the latter case, it was impossible to retrieve any detail in the sky.
The final image was achieved with the following Lightroom settings. Exposure +60, Recovery +41, Fill Light +94, Contrast +76, Clarity +56 and Sharpening +57.
In Photoshop, Image>Adjustment>Levels to give a range of 3 - 255 with a mid-tone reading of 1.11.
I think that this final image is an extreme example of the noise problem when using a high ISO setting. Perhaps the answer would be to take several images at different exposures and to then combine them using HDR techniques (which I have yet to try!).
4. Mixed lighting conditions (e.g. daylight + incandescent, fluorescent + incandescent)
Mixed Lighting Image 1
A dusk shot in Victoria Square, Birmingham combines evening sky with lighting both on the Council Offices and within the water feature.
The un-processed shot, using a tripod and 5 second exposure, is as follows.
Apart from ensuring that there was sufficient light in the sky to define all the buildings, I used a tripod to obtain a long exposure in order to give a smooth appearance to the water and provide shape to the water cascading from the fountain. Live View indicated that there were no great highlighting issues, apart from those resulting from the bright lights in the pool, which I judged to be acceptable.
The processed image is as shown below.
Apart from a little straightening of the image and removal of a couple of cranes showing above the Town Hall building on the left, I have made the image a little punchier by increasing the contrast and clarity. Despite using the Recovery slider, the histogram still showed highlight clipping but I presume that this was from the pool lights.
The Lightroom adjustment settings were Recovery +52, Fill Light +6, Blacks 0, Contrast =$&, Clarity +63, Vibrance +20 and Sharpening +50. In Photoshop, Image>Adjustments>Levels to a range of 8 - 255.
Mixed Lighting Image 2
Another example of 'mixed lighting' is a photograph taken indoors at Bolsover Castle in Derbyshire. It is a stairway lit by both daylight from a window on the right (and one behind) and a fluorescent light on the ceiling (above left) which provides detail on the ceiling. The un-processed image is shown below.
The photograph was taken using a tripod, which enabled a longish (0.3 seconds) exposure at ISO 100, using a wide angle lens (11 - 16mm). This avoided the disadvantages of using a high ISO. Other camera settings were f/11 and Auto WB.
The processed image is as follows.
By increasing the exposure setting in Lightroom and using some Fill Light, the image is improved greatly (without the 'noise' that a high ISO may have introduced by this increase in the Exposure setting). The Lightroom adjusted settings were: Exposure +51, Fill Light +36, Blacks 0, Contrast +86, Vibrance +56 and Sharpening at +50. WB was adjusted to 4400.
Again, I think a key is the use of the tripod and, in the latter case, framing the shot so that the fluorescent light was not in the image.
Conclusion
I think that I need to do some more experimenting with high ISO in circumstances where no tripod is available.
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