[Sidefx-houdini-list] aperture focal length relations

Mario Marengo mario at axyzfx.com
Thu Jun 21 14:25:53 EDT 2007


On June 21, 2007 02:08 pm, Gene Dreitser wrote:
> Heya Mario,
>
> If i'm not mistaken those number and letters represent common photographic
> formats.
>
> In the case of 135 (35mm film, the exposed neg size is 24x36 mm)
> 120 typically used in medium format cameras (with aspect of 6x6 or 6x7)
> APS advanced photographic system -- which I don't think ever really went
> anywhere... (the neg is even smaller then 35mm) and LARGE is, well, large
> format (usually bellows cameras...)

Hey man. Thanks!
So the only unclear thing there (to me) is what exactly do you mean by '6x6' 
and '6x7' in the 120 case. You mention ratio, so do you mean 6:6 and 6:7? And 
is that width:height or height:width? And are we talking actual distortion or 
mere 'pixel aspect' here?

@Adrian: Jim found a similar calculator in the Canon site here:
http://www.canon.com/bctv/calculator/index.html
where they make a distinction between '35mm Still' and '35mm Movie' (with 
significantly different width/length values for each!)... just FYI, because 
the site you pointed to uses only the values for '35mm Still', so watch out.


-- 
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Mario Marengo                                  mailto:mario at axyzfx.com
AXYZ ANIMATION                                 http://www.axyzfx.com
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