Digital Photoguide

Part 3 - Introduction 

October 2004 Magazine

Part Three of Digital Photoguide describes digital photography terms like megapixels, jpeg, tiff, compression, 8-bit and how they relate to each other. It also explains the size of a digital sensor and how it impacts the lenses you would use to capture a particular scene compared to with a 35mm film camera.

Digital Sensor Size and Lenses
The diagram below shows the sensor of a typical digital SLR compared in size to a 35mm film frame.

 The sensor covers less area than the film frame. If you want the same composition to appear on the digital sensor compared to a film camera you have to use a wider angle lens. A table in the printed magazine summarises the equivalent lenses. An actual examples is shown below. The same subject matter is the same – an Irish rail beet train – with two pictures, one taken on a 35mm film camera with a 50mm lens and the other on a digital camera using a 35mm lens. You can see that the angle of view is almost the same – in fact the 50mm on the film camera is very slightly wider.

(Note that both pictures had their contrast and colours adjusted slightly compared to the “original” and show that film and digital can render the same subject in a very similar way. Both pictures are low resolution for web display and can’t be used to compare the respective definition of film and digital)

Part Two

Part Four