Part 4: Light

"Light is our paint brush and it is a most willing tool in the hands of the one who studies it with sufficient care"   LAURA GILPIN

I have discovered with the regular use of my camera that the metered exposure is normally a little overexposed, i.e. the exposure the camera selects as ideal is typically longer than required. If I assumed the camera's meter reading to be correct, most of my pictures would be too light. For this reason I have the exposure compensation set at -0.7 for the majority of my shots. I have learned through experience that this is the ideal setting for most of my photography in aperture or shutter priority modes. Of course in some instances, as highlighted in the course guide ideal exposure may vary depending on the subject and/or surroundings. Flicking through some magazines I came across some images which rely on deliberate under or over exposure to achieve the desired effect.

Frame 1

In frame one, an advertisement shot for a pair of spectacles, the photographer has made a high key image to highlight the actual frames of the glasses, presumably to promote the successful sale of the product.

Frame 2

Frame 2, an image by Alixandra Fazzina shows a young Afghan boy during prayer. This low key image has incredible impact due to the shaft of sunlight permeating the otherwise underexposed surroundings, giving it an even more religious feel.

Exercise: Measuring exposure Part 1

For the first part of this exercise I was required to submit four images that have been deliberately over or under exposed.

Picture 1

Picture 1 is a classic silhouette of a golfer. Towards the end of the day my partner had played a shot and was walking back to the buggy. I asked him to stop while I grabbed my camera. Using the ground and cloud lines to divide the frame I fired off a shot using -2.0EV to achieve the silhouette effect.

Picture 2

Picture 2, taken inside a cathedral was deliberately underexposed to highlight the shafts of light streaming through the windows. This was a little tricky and I shot in manual mode, taking three bracketed exposures to achieve this result. I find the sun rays give this image a deeply religious feel but of course that is down to individual interpretation.

Picture 3

Picture 3 could have been a regularly exposed image but the background was a little fussy and the subject was quite shadowy. So I added a burst of fill in flash at 1/25 power and ended up with what I consider to be a quite pleasant high key image.

Picture 4

Picture 4 is another image shot into the light. This one was taken just as the sun had set and whilst it is yet another silhouette, I like the fact that the sky is almost layered from very dark to very light from top left to bottom right of the frame.




Exercise: Measuring exposure Part 2

For this exercise a series of bracketed exposures will demonstrate how varying the amount of light which reaches the sensor (or film) makes a difference to the final image. Using an average meter reading for each individual image as the starting point the aim is then to over and under expose the same image, noting the differences.

Image 1 1/1000 @ f8

Using an architecture shot as my first example I took Image 1 at 1/1000sec @ f8. This was the ideal exposure indicated by the camera's light meter. The sky looks about right but the building itself appears to be too light.

Image 1 1/1000 @f7.1

Opening up by half a stop has lightened the sky although this part is still pretty close to how I saw it. The building is obviously still too light.

Image 1 1/1000 @ f5.6

Now a full stop above the averaged meter reading the image is completely overexposed. The sky has started to blow and the detail in parts of the building is burning out. This image isn't really useable.

Image 1 1/1000 @ f10

Stopping down by half a stop to f10 has achieved what I would consider to be the optimum exposure. The sky is still nice and blue but the details on the building appear more true to their actual appearance, particularly the red parts.

Image 1 1/1000 @ f11

A full stop of underexposure has resulted in an image that is slightly too dark, although not to the same extent as the +1 overexposed shot was too light. The sky is slightly darker than as seen and it would appear that vignetting is starting to appear in the corners. The building itself still doesn't seem to be too badly rendered.

Image 2 1/80 @ f8

Image 2, a picture of a gentleman sitting on a train, uses available daylight from the right hand side through a window. The inside train lights have provided the light for the left hand side.Taking a meter reading from the right hand side of the man's face (as we look at it) has provided us with this good exposure.

Image 2 1/80 @ f5.6

Opening the aperture by a complete stop has washed out the right hand side of the image leaving a lack of detail in the hair and facial features on that side. Consequently the exposure is better on the left hand side.

Image 2 1/80 @ f6.3

At half a stop over, a little more detail has been retained in the right hand side. The left side of the image is a little too dark again but overall this isn't too bad a compromise.

Image 2 1/80 @ f10

Half a stop of underexposure has provided a lack of significant detail in the left side of the image, in this instance because there is not enough light as opposed to too much at f5.6. The right side of the image is still quite well rendered.

Image 2 1/80 @ f11

At f11 the image is too dark overall. The left side is almost completely in shadow.

Image 3 1/1250 @ f8

Shooting slightly against the light the averaged meter reading has again given a good account of itself. The colours have been reproduced with a reasonable degree of accuracy and there appear to be no blown highlights.

Image 3 1/1250 @ f6.3

Stopping up by half a stop has made an appreciable difference in this instance. The pink table top looks a little too pale. The orange coloured drink also looks far lighter than it actually is, as does the bottle top which now lacks any definition and texture.

Image 3 1/1250 @ f5.6

A full stop of overexposure has changed everything quite dramatically. The table colour is now far too pale. The orange colour has started to blow and is almost white in the full sun. The edge of the shadow appears less well defined.

Image 3 1/1250 @ f10

Stopping down by half a stop obviously has a darkening effect. However the colours are still fairly accurate and there hasn't been too much loss of detail, the bottle top actually looks better. An acceptable image.

Image 3 1/1250 @ f11

The full stop of underexposure has not rendered this image unusable. OK, it's darker than the average metered shot but not as relatively dark as the stopped down version of image 2 for example. The front of the bottle top has started to descend into shadow, as has the bottom of the orange juice. The shadow is now very well defined.

Image 4 1/1600 @ f11

Interestingly in image 4 I believe the meter has overexposed the "real" subject but made a pretty good job of the reflection in the windows of the office building to the right. This is probably due to a significant portion of the frame being dark due to being shot from a poorly lit side street.

Image 4 1/1600 @ f9

Now, with the aperture opened up by half a stop to f9 the difference between the "two skys" doesn't seem quite so pronounced. I find this a little puzzling. Overall the image is quite overexposed.

Image 4 1/1600 @ f8

At a full stop of overexposure we are getting towards parity with the shades of blue so I'm starting to think the darker reflected blue blows out at a slightly faster rate. Anyhow this image portrays The Shard as a blinding white wedge with very little detail to offer the viewer.

Image 4 1/1600 @ f14

The slightly stopped down take of this shot at f14 gives the best exposure in my opinion. Both the real tower and the mirror image are reasonably well detailed and the sky is pretty much as seen. The fact that the foreground is now disappearing into shadow helps to keep the viewers attention on the subject itself.

Image 4 1/1600 @ f16

At f16 The Shard is now very well rendered. It is, after all, the main subject matter in this shot. Or is it? The reflection is now a little too dark. Obviously we have to lose a little light as we are receiving it second hand so to speak. It's a nice image but I personally prefer the previous one.

Image 5 1/100 @ f8

In this image the orchids have been shot in incandescent light with a natural backlight through a window. An averaged meter reading, I think this is a little too dark, more light was needed on the flower heads.

Image 5 1/100 @ f5.6

A full stop of overexposure is a little too much. The petal edges are starting to blend into the background giving the image very little depth.

Image 5 1/100 @ f6.3

Opening up by half a stop has given what I believe to be the best overall exposure given the lack of direct frontal light. The background is still a little bright but the inner parts of the flowers are now more clearly detailed.

Image 5 1/100 @ f10

Stopping down by half a stop has been beneficial for the outer petals as these are now well detailed. However the inner parts of the flowers are too dark and the confusing background is now becoming more of a distraction.

Image 5 1/100 @ f11

A full stop down and the image has nothing going for it under the present lighting conditions. A short burst of very weak fill-in flash would have made a great difference.

Image 6 1/800 @ f8

Image 6 has a highlighted building at the end of a much darker street. In this average meter reading neither elements are particularly well exposed. The Cathedral at the end of the street is too bright whilst the street itself is too dark.

Image 6 1/800 @ f6.3

Opening up by half a stop hasn't really made a hugely appreciable difference. Obviously the Cathedral is even brighter now but we are starting to see a little more detail in the street, although it is still very dark.

Image 6 1/800 @ f5.6

With a full stop of overexposure the cathedral as expected is almost completely blown. But in this instance even the street appears wishy washy. While it is exposed slightly better there is an obvious lack of detail, presumably due to the poor amount of direct light entering it.

Image 6 1/800 @ f10

At f10 the Cathedral is now much better rendered to the obvious detriment of the street details. However I find this image the most pleasing to the eye as your attention cannot help but be drawn to the main subject, the cathedral itself.

Image 6 1/800 @ f11

Here we have the Cathedral represented probably exactly as I saw it on that day. But how dark the street now appears. As this area occupies about 75% of the frame the full stop of underexposure has had the effect of darkening it quite dramatically.







I found this exercise very interesting, particularly with the use of vastly different lighting conditions. Image 6 was the standout example for me. Two areas of extremely different light captured within the single frame has bamboozled the camera's light meter although it actually didn't do too shabby a job with its attempt at an ideal exposure. This image more than any other highlights the difference between the human eye and the camera lens.


Exercise: Higher and lower sensitivity

Thinking back to the Visions of Light workshop that I attended in March, one of the solutions presented to us when faced with a situation in which the shutter speed required to capture a subject was too low to avoid camera shake would be to "dial up the iso". To a number of people this would instantly lead to the issue of "noise" rearing it's ugly head. But advances in sensor technology appear to be handling that situation remarkably well.

Frame 1 1/500 @ f2.8 200mm iso200

Here we have a crow sitting in an apple tree shot through a window. At iso200 a shutter speed of 1/500 has been selected by the camera. Handholding this 70-200mm lens at that shutter speed is just about possible with VR switched off. Zooming in to the image however indicates a small amount of shake. This image would be perfectly presentable in postcard size but an A4 print would look slightly blurred due to the shake.

Frame 1 1/2500 @ f 2.8 200mm iso1000

With the iso increased to 1000 the shutter speed has also correspondingly increased to 1/2500. This makes the lens much easier to handhold. At this size it appears not to have made a difference but zooming in should tell us something else.

Low sensitivity

Zooming in, the differences between iso200 and iso1000 become more apparent. The speckled appearance of the high sensitivity image is due to noise. At the low sensitivity the noise is almost invisible. 

High sensitivity

What must be noted here however is the difference in the sharpness of the leaves. As previously noted, handholding a long lens can lead to camera shake. Without some form of support, increasing the iso is the best way to increase sharpness in some instances. The trade off obviously is increased noise.

High sensitivity

Low sensitivity

In the darker areas of the frame the noise is clearly evident at higher sensitivity.











Again, at lower sensitivity the noise is much more controlled but at the expense of a little camera shake.

Frame 2 1/40 @ f2.8 20mm iso200

Frame 2 was taken very early in the morning using a much shorter focal length (20mm). At first glance there appears to be very little difference between the images taken at iso200 and iso1000.

Frame 2 1/200 @ f2.8 20mm iso1000

Low sensitivity

High sensitivity

 Cropped in to a darker area reveals the difference in the appearance of noise between the two images although this isn't as significant as in the previous frame. At a focal length of 20mm camera shake isn't as much of an issue. In this light using a telephoto lens would have been very difficult without a tripod or other means of support.

Frame 3 1/25 @ f2.8 50mm iso200

Frame 3 1/125 @ f2.8 50mm iso1000

In this particular image the presence of high iso noise is already evident before the enlargement of a particular area. At such a low shutter speed camera shake could again have been a problem at iso200, under normal circumstances I would probably dial the iso up a notch or two as high as iso400. This would reduce the possibility of camera shake but also keep noise levels to a minimum.

Frame 4 1/100 @ f11 36mm iso200

Frame 4 1/500 @ f11 36mm iso1000

A street scene photographed in a shaded area has produced two images that seem pretty much identical at normal zoom levels. There appear to be no discernible differences in the highlight or shadow areas at first glance. If anything the low iso image appears to be slightly overexposed.

Low sensitivity

High sensitivity

I was surprised to see so little difference between the two cropped images. The dark areas appear very similar, only in some of the very light areas can we see a slight change in the amount of image noise present. In this example the camera's sensor has handled the situation very well indeed.





 

Frame 5 1/60 @ f8 27mm iso200

In this instance I have used a higher sensitivity to freeze the movement within the frame. At iso200 and using aperture priority, the shutter speed appointed by the meter hasn't been enough to capture the cyclist sharply.

Frame 5 1/400 @ f8 27mm iso1250

Dialling the sensitivity up to iso1250 has increased the shutter speed and enabled the movement of the cyclist to be frozen.

Frame 6 1/15 @ f11 19mm iso200

Frame 6 1/80 @ f11 19mm iso1000

This frame demonstrates that even at a small print size, high iso noise can become an issue in certain lighting, as with Frame 3. Despite the obvious advantage of having less camera shake due to the higher shutter speed the higher sensitivity image is really too noisy to be useful.




This was another really useful exercise. As I was advised by Andy Rouse on the Visions of Light workshop, if you need more speed dial up the iso. With today's processing technology, high iso noise isn't always going to be an issue. This isn't always the case of course but as I've discovered in a couple of the scenes I shot, it doesn't necessarily apply that any photograph shot at iso1000 HAS to be noisy.