On 4 Nov 2005 at 14:25, keith_w wrote:

> Alla my 35s have a solid rectangular opening in the camera body, thru 
> which the light rays pass.
> It's THAT that forms the outline of the exposed image on the film.
> That being the case, how can a different lens, with a changed light 
> bundle size mean anything at all? It's all chopped off by the body 
> opening...
> 
> Iguess it's conceivable some other cameras don't follow that design 
> convention, so... just a comment. And a question.

I don't know of any film body where film gate sits flush on the film, the film 
generally sits on rails so there is a slight gap between it and the mirror/lens 
box. If a lenses rear elements are far from the film plane it follows that the 
rays will pass from the lens and onto the film at a smaller angle than that of 
a lens which (particularly in the case of a RF camera) may protrude into the 
body cavity. 

So in short a lens will project a frame on the film relative to the angle of 
the rays exiting it due to the fact that the aperture that masks the film is 
slightly forward of the plane of focus.

Cheers,


Rob Studdert
HURSTVILLE AUSTRALIA
Tel +61-2-9554-4110
UTC(GMT)  +10 Hours
[EMAIL PROTECTED]
http://members.ozemail.com.au/~distudio/publications/
Pentax user since 1986, PDMLer since 1998

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