Fate
TPF Noob!
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lol thats awsome hertz..... but it went straight over my head
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Hertz van Rental said:Bellows is to do with close-up work ....Actual exposure time=metered exposure x bellows extension squared/focal length squared
I can say all that in my sleep
I'm a little confused. I understand how with e.g. an extension tube the image projected onto the film/sensor will be dimmer than if you use the lens at its native focal length(s). But I don't get how the exposure will be off if you are using a camera with TTL metering. If the lens is projecting a dimmer image, wouldn't the meter just read for a longer/wider exposure? Or am I missing the point?Hertz van Rental said:Bellows is to do with close-up work - usually with 5x4/10x8 but you can get it with extension tubes.
Exposure meters and f-stops work on the principle that the image is formed one focal length behind the lens. Approximately true for normal circumstances.
When you focus on an object near to the lens the image is formed much further back behind the lens. The inverse square law means that the image will be much dimmer and so the exposure will be wrong.
An object at 2 focal lengths from the lens will therefore produce an image 1/4 as bright as the indicated exposure.
Bellows factor allows you to compensate for this effect.
Actual exposure time=metered exposure x bellows extension squared/focal length squared
I can say all that in my sleep
Lumix said:One good eye and a quick finger.
:lmao: As you were, Lance Corporal Jones.Rob said:They don't like it up 'em, Captain Mainwaring Sir!