Brief: Find a scene that has depth. From a fixed position, take a sequence of five or six shots at different focal lengths without changing your viewpoint. (You might like to use the specific focal lengths indicated on the lens barrel.)As you page through the shots on the preview screen it almost feels as though you’re moving through the scene. So the ability to change focal lengths has an obvious use: rather than physically moving towards or away from your subject, the lens can do it for you
All shots taken in Lincoln Cathedral using a Canon EOS 5D Mark III and a Canon 24-105mm f4.0 L ISM lens. All shots were taken just before 10.30am. The light in the cathedral was really tricky and I had to play around with the ISO to get the best shots using the same Aperture setting of f5.0.
1/40 sec @ f5.0, FL 32mm, ISO 1600
1/40 sec @ f5.0, FL50 mm, ISO 3200
1/40 sec @ f5.0, FL 67mm, ISO 3200
1/40 sec @ f5.0, FL 105mm, ISO 12800
Does zooming in from a fixed viewpoint change the appearance of things? If you enlarge and compare individual elements within the first and last shots, you can see that their ‘perspective geometry’ is exactly the same. To change the way things actually look, a change in focal length needs to be combined with a change in viewpoint.
Using a telephoto lens has a narrow angle of view which means that the relative size of objects are normalised when compared to those further away.
Cambridge in Colour: A learning community for photographers http://www.cambridgeincolour.com/tutorials/telephoto-lenses.htm [Accessed 18th October 2015]
I had to check the Exif data twice on the last two shots because I was really surprised that the difference between the two shots was miniscule. This was despite increasing the focal lens by 38mm whereas, the increase in focal length between 2 and 3 was only 17mm and there is a considerable change in the appearance of the organ or at least the amount of area that can be seen around the organ.
As the perspective moves further towards the organ the dynamic points of the lines of pillars and ceiling arches disappear and the detail on the arches themselves become more pronounced and visible.
Image 1 demonstrates the sheer scale of this magnificent building whereas the others shots begin to allow the viewer to appreciate the complexity and beauty of the detail.