Sunday, 28 February 2010

Project: Getting to know your Camera

At last I have tackled the first of these exercises. I have had this particular camera for just over a year. The EOS 50D manual tells me several things about my camera which are pertinent to this project:
  • The image sensor size is 22.3 x 14.9
  • Aspect ratio is 3:2
  • Viewfinder coverage is 95%

What does all this mean. The sensor size means that I have a much narrower angle of view, than a camera with a larger sensor. Typically equivalence to a 35mm frame is used when making comparisons, and in this case, 35mm equivalence is 1.6 times the focal length of the lens. In other words, the sensor in the 50D is 60% of a full size or 35mm "frame". Canon have, however, retained the 3:2 aspect ratio which existed in film cameras.

Viewfinder coverage is not full size, which means that for this exercise, the sensor sees more than I do. I have found this to be somewhat of an irritation at times - careful cropping in the viewfinder is un-done if allowance is not made for the smaller coverage.

So, for this exercise, I walked up the street to a somwhat old, wall-mounted post box. The lens I used for this exercise was a 24-105 zoom. As suggested I had both eyes open and tried to match the view in both eyes - a rather curious effect occurred whilst adjusting the focal length - the image seemed to pop in and out steadying when the image size was approximately the same.

The result is shown below:

I estimated from the lens barrel, that this "standard" focal length was 55mm. The Exif data gives it at 57mm.

The following two shots show the view at 24mm and 105mm. I decided not to use a lens with a longer focal length, as I felt that would not add to the knowledge gained from this exercise.



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