Part two – Project 1 – Exercise 2.2
“Select your longest focal length and compose a portrait shot fairly tightly within the frame in front of a background with depth. Take one photograph. Then walk towards your subject while zooming out to your shortest focal length. Take care to frame the subject in precisely the same way in the viewfinder and take a second shot. Compare the two images….”
I used the same alleyway as I did in Exercise 2.1, so it may be familiar to you. I had my model stand in the same position and I moved myself with the camera secured to a tripod, to ensure the images were taken from the same view-point, to a position which meant the framing of the model was the same but with two different focal lengths. I used two lenses a Canon 70-300mm f/4-f5.6 and took an image at the longest focal length of 300mm (full frame equivalent 480mm) and then took an image with a Sigma 17-50mm f/2.8 using the shortest focal length of 17mm (full frame equivalent of 27mm).
As you can see from above images the differences are quite considerable. Firstly the image of the model taken at the longest focal length of 300mm is far more flattering. It makes the model look more compact, her shoulders look broader and her head looks smaller but this compression makes for a nicer image. The longer focal length brings a nice bokeh to the background and actually brings the background elements closer. The background elements in view, albeit blurred, are in fact hidden behind the model in the 17mm image.
In contrast the 17mm image makes the model look rounder, she has a rounder face and narrowing shoulders. You can see the distortion in the background with the walls appearing to splay outwards. The background has more in it and is more in focus even though it has been taken with a larger aperture, which would usually produce a more out of focus background, this demonstrates that focal length also has an impact on how much background blur there is.
“As you page between the two shots it can be shocking to see completely new elements crash into the background of the second shot while the subject appears to remain the same. This exercise clearly shows how focal length combined with viewpoint affects perspective distortion. Perspective distortion is actually a normal effect of viewing an object, for example where parallel train tracks appear to meet at the horizon. A ‘standard lens’ – traditionally a 50mm fixed focal length lens for a full-frame camera (about 33mm in a cropped-frame camera) – approximates the perspective distortion of human vision (not the angle of view, which is much wider). A standard lens is therefore the lens of choice for ‘straight’ photography, which aims to make an accurate record of the visual world.”
In reality the ‘real’ proportions of the model sit somewhere between these two extremes but it is interesting to experiment to see how you can influence shape, form and the elements included within the frame of an image by using different focal lengths. Depth of field, relating to different apertures, are also affected by focal length.
This completes my submission for Exercise 2.2. You can access Exercise 2.3 here.