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Re: [OM] f/0.x lenses

Subject: Re: [OM] f/0.x lenses
From: pizzuto <pizzuto@xxxxxxxxxxxxxxx>
Date: Thu, 11 May 2000 23:04:12 +0200
May I ask a technicality?

I always understood the f number to refer to the ratio of the actual
scenery light intensity appearing inside a lens.  Ex: f2 would let in
1/2 the light intensity.  Ergo, wouldn't f < 1 imply that light
amplification was taking place.

Or am I the shame of the Oly list with my wrong understanding of the f
number... grin..

Konrad

Erwin Voogt wrote:
> 
> Hi,
> 
> Konrad wrote:
> ------
> I'm sure you've all got 8mm/0.8f's ... they're round-shaped and they
> give you more light than's available in the scene... bulbs?...
> 
> hehe...
> 
> Konrad
> ------
> 
> Well, I know some people who use 50 mm F0.75 (or something close to those
> specs) lenses from X-ray camera's to take astronomy snapshots. With such a
> lens and a ISO 1600 film you get nice colourful Milky Way pictures in
> seconds. The quality is not excellent, but the same holds for the Zuiko 50
> mm primes wide open. The F0.75 lenses are quit bulky and the back element is
> very close to the film, so to mount them on a reflex body requires a little
> modification: removing the mirror...
> 
> Bye
> 
> Erwin Voogt
> Utrecht, The Netherlands
> 
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