Focal Length and Angle of View

To establish the way I perceive what I see though the viewfinder I took a series of three photographs. All were taken at a different focal length to demonstrate the relationship between viewfinder, focal length and angle of view.
The view is from the balcony of my house at around 10am. Two reasons;
1) It was about to pour with rain.
2) It was accessible and next to my computer and printer!

The outcome was surprising to me because it was the ‘standard’ focal length which caught me unawares. This is it;

Technical – f/10, 1/400, ISO400, 35mm

The surprise was not that the shot should have been at 35mm as the text in the course material and ‘Sony NEX-5 – Guide to Digital Photography’ -(David Busch) already explains that a 4/3 camera (a Sony NEX-5) will have a different ratio of focal length in comparison to a ‘full-frame’ camera. This actually works out to a 52mm shot  if taken with a full-frame camera. However, what I didn’t take into account was that, as standard on a Sony NEX-5, there is only a 3″ LCD to view through. This is my view finder. The image that looked closest in the viewfinder to what was asked for in the brief turned out to be around an 80mm shot. But, when it was printed, bore no relationship to what was being asked for. The shot was zoomed-in and I couldn’t hold it far enough away to make it fit the ‘jigsaw’ of the scene in front of me. So in fact I had to experiment a little and work out what the full-frame size should be (i.e. around 50mm) and work backwards. This brought me to the 35mm photograph as described above. After printing I could could hold the print comfortably and a bent arms-length (around 50cms) so that it fitted the background. Quite obviously a lesson learnt and not something I had been aware of before. The exact science of the focal length and relationship to the sensor size had never been broached by me before. A great exercise in that respect and something to watch out for for the future.

The other two photos were much more straight forward in the sense that they did what was expected by me. The wide angle shot needed to be almost touching my nose before it fitted with the background. The zoomed-in shot would have needed telescopic arms to have done so.

Technical – f/10, 1/200, ISO400, 16mm

Technical – f/10, 1/250, ISO400, 210mm

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One thought on “Focal Length and Angle of View

  1. Pingback: Standard focal length | BA Blog

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