[Sidefx-houdini-list] film size to digital focal length

Jeff Higgins jeffrey.higgins at gmail.com
Tue Jun 19 06:18:21 EDT 2007


i think what you have to do is multiply your focal length by a lens
conversion factor (from hd camera to film camera) to adjust to the different
ccd sizes.

the lens conversion factor is the ratio of your hd camera aperture (this
will be your 1") to a standard film camera aperture (i don't recall what
this is, but if you have an american cinematographers manual handy it should
be in there else google it).

the only other thing to watch out for is the units.  the focal and aperture
need to be expressed in the same units.  The focus just need to be in what
ever scene units your using.

hope that helps!

jeff

On 6/19/07, Adrian Lee <dryrainstudios at gmail.com> wrote:
>
> Morning all,
>
> Does anyone have a reliable way of equating given focal length to houdinis
> cameras. Or maybe a look up table
>
> I  have a shot and I am unable to track and get the info that way.
>
> The shot info is limited, but I have been given,
>
> lens - 40mm
> medium close up focus - 5 feet 6 inches
>
> I know it is shot on a phantom high speed camera with a a inch x inch
> sensor
> producing a 1024x1024 image.
>
> Any help would be very welcome
>
> thanks
>
> Ed
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