Focal Lengths

The object of this exercise was to help me appreciate the change in composition of a photograph by changing the focal length of my camera (i.e. zooming in or out of the subject) from the same point. I used a tripod and picked a large container ship in the distance, using the open sea as the foreground. My Focal lengths ranged from 16mm to 210mm and I took a series of nine shots to note the gradual change in the way the image looked and felt. At points I panned across the horizontal to keep the large ship in a suitable position for the composition. Apart from that, the other in-camera factors remained constant.

Here are the results starting with the widest shot;

Focal length 1 – ISO200, f/11, 1/500, 16mm

Focal length 2 – ISO200, f/11, 1/500, 26mm

Focal length 3 – ISO200, f/11, 1/500, 35mm

Focal length 4 – ISO200, f/11, 1/500, 52mm

Focal length 5 – ISO200, f/11, 1/500, 82mm

Focal length 6 – ISO200, f/11, 1/640, 104mm

Focal length 7 – ISO200, f/11, 1/500, 144mm

Focal length 8 – ISO200, f/11, f/500, 180mm

Focal length 9 – ISO200, f/11, 1/500, 210mm

Starting at a wide angle gives an ideal start to this exercise. The ship I am focussed on is barely perceptible on the horizon but on closer inspection can be seen quite clearly with my digital loupe. It does indeed look exactly the same as in the final ‘zoomed-in’ shot with the other smaller vessels around it.
There are two things which come to my attention as I look at the series. First, even though I have kept the horizontal plane exactly the same for the series there is a noticeable ‘shift’ from beginning to end which can be seen from the horizon point. As this is gradual throughout the shot sequence I would suspect it is because I am shooting ‘upwards’ toward the subject meaning that the zoom is accentuating that path as I zoom in further. The net result is that I end up with 2/3 sky and 1/3 water in the final image whereas it is more like 50/50 in the first (Focal length 1).
Secondly, the quality and contrast of the image suffers as I continue to zoom. This can also be seen over the course of the shots. I can think of two reasons which would combine to make this happen. First, I started with a wide-angle lens and changed to a telephoto lens during the course of the series. The telephoto lens has the effect of flattening out a shot. Combine that with physically having more glass in a telephoto lens and I would expect to see the quality suffer (especially as I suspect the wide-angle lens is a better quality). Second, the ‘haze‘ in the air. Although quite a clear day, this will affect the quality. Zooming towards my subject it has the effect of condensing the haze particles between me and the ship making the vision more limited. If I had had a larger zoom then the results would have been more pronounced.

The final shot is just a magnification of the first shot and both have their merits. However, the change of focal length gives a dramatic change to the look and feel of the images. The first shot is of an apparently serene scene, maybe with some ships on the horizon but certainly with nice blue sky, some shoreline for perspective with small boats scattered around. The final shot is one of a busy shipping lane with all manner of vessels going about their business, with not a hint of seaside to be seen. Although the relationship between the objects is the same in the final shot, when taken out of context with the first it gives a different feel to the relationship. Having effectively cropped out the sunny seaside stuff, it becomes a much more industrial scene even though it contains within it the same subjects as the first image.

All photographs taken on location at East Coast Park in Singapore.


One thought on “Focal Lengths

  1. Pingback: Focal Length | BA Blog

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