FOCAL LENGTHS

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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A 800 mm 100-400 lens + X2Image 1

800mm    100 – 400mm telephoto + x2 teleconverter lens

B 400 mm 100-400 mm lens

Image 2

400mm    100 – 400mm telephoto zoom lens

C 200 mm 100-400 mm lens

Image 3

200mm   100 – 400mm telephoto zoom lens

D 200 mm 70-200 mm lens

Image 4

200mm   70-200mm telephoto zoom lens

E 100 mm 100-400 mm lens

Image 5

100mm    100 – 400 mm telephoto zoom lens

F 100 mm 100mm Prime lens

Image 6

100mm   100 mm prime macro lens

G 100mm 70-200 mm lens

Image 7

100mm    70 – 200mm telephoto zoom lens

H 70 mm 70-200mm lens

Image 8

70mm     70 – 200mm  telephoto zoom lens

I 70 mm 17-85 mm lens

Image 9

70mm    17 – 85mm standard zoom lens

J 50 mm  17-85 mm lens

Image 10

50mm    17 – 85mm standard zoom lens

K 17mm  10-22 mm lens

Image 11

17mm    17 – 85mm standard zoom lens

L 22mm 10-22mm lens

Image 12

22mm    10 – 22mm wide angle lens

M 10 mm 10-22mm lens

Image 13

10mm     10 – 22mm wide angle lens

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M 10 mm 10-22mm lens  enlarged. JPG

Image 14

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.

IMG_2477   IMAGE 1A

          IMG_2479

     IMAGE 1B

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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