A few tips 'n tricks

Continued...
Image sensor size. The majority of digital single lens reflex cameras have an APS film sized image sensor (called APS-C). This film takes the place of conventional film and records the image. At the moment (July 2006) only Canon offer SLR cameras with the full frame image sensor.

When I bought my first DSLR, my widest lens was a 24mm which was adequate for the type of work was interested in. However, when mounted on the D60 and the 20D, the results were not what I wanted. The APS-C sensor in these cameras gave me images equivalent to those taken with a magnificaton ratio of 1.6 i.e a 38.4mm lens!

As most of my images are made at the wide angle setting, I invested in a 20mm lens which, with the aforementioned magnification ratio, was equivalent to a 32mm lens.

Finally after not being able to get the coverage I required, I invested in a Canon EF 17 - 40mm zoom which, was roughly equivalent to a 27 - 64mm lens.

Here you can see what I'm explaining above. The grey area shows the image circle. That is the image displayed on the film or sensor. This image circle covers the 24 x 36 mm dimensions of 35 mm film (the light blue area). The yellow area shows the APS-C sensor and clearly illustrates the size difference.

I ws pleased when Canon announced the introduction of the 5d because now I would be able to use my wideangles "properly"

The first thing I did after unpacking the 5d body was to take a side by side comparison picture to show the difference in coverage between the two sensors. Below, you can see a picture taken out of my window. This was taken with the Canon 20d and a 17mm lens. Placing your mouse over the picture (you don't have to click) shows how much more image is recorded when using the same lens on my new EOS 5d body.

For more info about the differences in image sensor size, there is a well written article by Bob Atkins which can be found here

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