The objective of the project is to understand the relationship between the focal length of the lens and the angle of view.
Included in this was to understand the ‘standard’ focal length for my camera.
The first exercise was to establish what the ‘standard’ focal length of my camera. Given the Sony Alpha 900 is a full-frame camera I had expected the standard focal length to come in somewhere around 50mm so was surprised to find that it actually came in at about 70mm when using the CZ24-70:f2.8. For the telephoto shots I used the Minolta Beercan (70-210:f4) which gave exactly the same result at 70mm.
For the pictures I chose a derelict farm building that I had noticed when driving along one of the local country roads recently. There’s something rather sad about a building that once served a useful purpose and now lies broken. I intend to go back to this building again during one (or both) of the golden hours – I think the silhouetteof the building has the potential to look quite dramatic against a strongly coloured sky.
The images for this project are shown below individually. To view larger images in a slideshow of all images please click on any image.
Focal length for ‘standard’ lens
[EXIF: Sony DSLR-A900 at ISO200, f/8, 1/160 sec at 70mm]
Wide angle shot at 24mm
Note: this image was slightly cropped to take out the vignette from the circular polariser
[EXIF: Sony DSLR-A900 at ISO200, f/8, 1/250 sec at 24mm]
Telephoto shot at 150mm
[EXIF: Sony DSLR-A900 at ISO200, f/8, 1/1000 sec at 150mm]
Telephoto shot at 210mm
[EXIF: Sony DSLR-A900 at ISO200, f/8, 1/1000 sec at 210mm]
Sadly I won’t be able to get any closer to the building when I do go back
[EXIF: Sony DSLR-A900 at ISO200, f/8, 1/250 sec at 210mm]
Conclusions drawn from this project
The first conclusion I drew was that my expectations of what the standard focal length for my camera were wrong. Instead of being around 50mm it was 70mm.
As expected, shooting at a smaller focal length (wide angle) shows a much wider scene and objects appear smaller. Perspective is also affected, with objects further away seeming smaller/further away in relation to objects in the foreground.
Conversely, shooting at longer focal lengths (telephoto) shows a narrower field of view with objects appearing much larger. The perspective is also affected with distant objects appearing closer to those in the foreground than is the case.