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Old 29-07-2006, 03:29 PM
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Kev Lewis Kev Lewis is offline
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Re: what does a fast lens actually mean

Everything you want to know about aperture and shutter speeds
Everything you want to know about Depth of Field

The exam will take place at 7pm and will consist of 128 multi-answer questions followed by the practical test


Quote:
Originally Posted by ollyk
Am I right in thinking that the f number is derived from distance from lens halfway point to film plane divided by equivelent diameter of the Iris? It certainly explains why the f# is reversed!
Regarding Aperture and Depth of Field, I would like to be able to visulise exactly what is going on to increase the DoF when you allow more light in. I have seen a couple of diagrams and can't quite see why allowing more light in allows for a narrow focus range and less light allows for a larger focus range...? Can anyone explain this to me please?
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