EXERCISE 1 – FOCAL LENGTHS
The aim of this exercise was to use different lenses and a range of focal lengths to photograph the same subject in order to demonstrate the different images that resulted.
For the exercise I visited Strumble Head in north Pembrokeshire and set up my Canon 7D on a tripod on a cliff with a view of the nearby lighthouse. I used the following lenses set at different focal lengths to take the photographs : – Canon L series 100 – 400mm telephoto zoom lens with and without a X2 converter; Canon L series 70 – 200mm telephoto zoom lens; Canon standard 17 – 85mm zoom lens; Canon prime 100 mm macro lens; Canon 10 – 22mm zoom wide angle lens. The weather was overcast with rain threatening.
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800mm 100 – 400mm telephoto + x2 teleconverter lens
400mm 100 – 400mm telephoto zoom lens
200mm 100 – 400mm telephoto zoom lens
200mm 70-200mm telephoto zoom lens
100mm 100 – 400 mm telephoto zoom lens
100mm 100 mm prime macro lens
100mm 70 – 200mm telephoto zoom lens
70mm 70 – 200mm telephoto zoom lens
70mm 17 – 85mm standard zoom lens
50mm 17 – 85mm standard zoom lens
17mm 17 – 85mm standard zoom lens
22mm 10 – 22mm wide angle lens
10mm 10 – 22mm wide angle lens
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Image 13 expanded and cropped to show central image
What is clear from the above photographs is that whilst the image changes radically with a narrow field of view at the large focal lengths and a wide field of view at the small focal lengths, and the size of the actual subject within the frame becomes smaller with decreasing focal length, the actual proportions of the subject do not change. This is true for any of the lenses used, whether they be telephoto, standard, prime or wide angle.
This is particularly demonstrated in Image 14 above. Here I have resized the central subject in Image 13 by cropping and expanding and it can be seen that the proportions of the subject are identical to those in the other shots taken at greater focal lengths.
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EXERCISE 2. FOCAL LENGTHS AND DIFFERENT VIEWPOINTS
The use of lenses of different focal lengths can give very different images and perspectives. The following pairs of photographs demonstrate some of these effects with the shots taken either from the same location with a wide angle lens and a telephoto lens respectively or with a telephoto lens and then with a wide angle lens after moving the camera towards the subject until the same frame is achieved.
These two shots of the interior of the lookout at Strumble Head show how two very different images can be achieved from the same spot using a telephoto zoom lens set at its shortest (100mm) and its longest(400mm) focal lengths respectively focussed on the same place. The shorter focal length appears to have introduced some perspective problems (Image 1A) as the pillars on the left appear to be leaning outwards. However, I love the effect of the longer focal length which has foreshortened the perspective of the pillars and created an image which has some optical illusion qualities with the appearance of the different elements of the image changing as one looks at them.
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