To get the best results from this exercise, I felt that I had to use my longest lens. Although not the best quality lens, its superior range best shows the results of this exercise. So I fitted my 75-300 lens and set off for the Quantocks to look for some shots with depth to them. My plan was to walk a section of ‘The Coleridge Way’. After only ten minutes I stumbled across a small herd of Scottish Highland cattle.
I took a sequence of frames at focal lengths; 75ft, 105ft, 140ft, 210ft & 300ft (close to the fixed focal lengths on the barrel of the lens). In fact I took a total of four sequences so that it enabled me to compare them against each other to see if they differed structurally in any way.
The ‘Zoom’ or ‘Telephoto’ lens has always been popular for a number of reasons. Without moving from a fixed spot, you are able to ‘zoom’ in or ‘pull back’ from an object/subject matter. Obviously this is a huge advantage over a ‘Prime’ lens, which has a fixed focal length. Zooming in or out not only allows you to get closer or further away, but in doing so gives you the freedom to either get more detail (zooming in) or compose and balance a scene, by pulling back and allowing more subject matter in, thus allowing greater flexibility in composition.
The drawback of a Zoom lens over a Prime is that a Prime has a lot less glass in it and therefore is able to allow a lot more light in and the quality of the resulting image is better for having passed through less glass. A prime will also be able to open to a much wider aperture too. This will enable the operator to make use of very shallow depths of field. One other ‘feature’ of a Zoom lens is that image appear to have been ‘flattened’, by which I mean, even with great lead lines, the depth of the image appears to be foreshortened.
f9.5 @ 1/90 sec. focal length 75mm. ISO 400
f9.5 @ 1/90 sec. focal length 105mm. ISO 400
f9.5 @ 1/90 sec. focal length 140mm. ISO 400
f9.5 @ 1/90 sec. focal length 210mm. ISO 400
f9.5 @ 1/90 sec. focal length 300mm. ISO 400
From the starting point in image one, I took a further four shots. Comparing the last with the first you can see that the tree that I appear to be standing next to in image five (left side of the image) Is just left of centre in the starting image. This gives a good idea/indication of how far in the lens appears to travel.
Having now placed the images alongside each other I have been able to compare them all, and apart from the obvious ‘zooming in’ effect, something else which I have noticed is how the angle of vision changes from image to image. In effect, the lower the focal length, the wider the perceived ‘field of view’ is. So image one could be likened to the view that an owl would have, and image five is much more like looking at a view through a tunnel. This is why some ‘shorter’ lenses are called ‘Wide Angle Lenses’. Taking this a step further, the view that would most represent human vision would (in this instance) be the first one, shot at 75mm. It is a well-known fact though that the view closest to representing human vision would be at about 50-65mm.
Comparing image one with image five, it can be seen that image five has really isolated a rectangle of information within image one. That information (the picture) is identical only larger. Using a zoom does not allow you to see any additional information by zooming in past (in this case) the foreground trees. You are not able to see around a tree or any solid object. Zooming in only enlarges a selected area within a view that you already have. The only way to see anything in addition to the first shot would be to move to a different place to take the photograph.
The first set of images on my contact sheet demonstrate something a little different to the ones above, and that is, that Image five is a completely different picture to image one. In my examples above, the ultimate ‘point of the photo is the cows, from the first shot to the last. However with the first set in the contact sheet, you are more occupied by the approaching tree. By the time we view image five, the tree has disappeared and thus altered the balance and construction and composition of the image. Now you are solely looking at the meandering ditch going off into the distance and any meaning present in the first image is lost or altered beyond recognition.
I see! 