I'm well aware of that. But most often than not you can't do that because at best you'll get the lens and camera used. And sometimes you don't even have anything to match to in your scene to use to estimate the FOV while sitting at the tracking app of your choice. So sometimes all you can do is to get as close as you can with the information you have at hand and wish for the best.
The calculations manufactures use to calculate the focal length of a lens alone do have some degree of variation or rounding to make names simpler. After all no one buys a 17.786765mm lens, so it's true you can't bee too precise about this by using just the film back and focal length numbers alone, but it does tend to get you close enough to get good results in most situations. On Tue, May 29, 2012 at 7:19 AM, Julik Tarkhanov <[email protected]>wrote: > > On 29 mei 2012, at 09:37, Diogo Girondi wrote: > > But every time I had to match move things shot with the ALEXA, using the > camera sensor size and the actual lens value was enough to get me there. > > Hate to sound like a broken record but what helps the most with this kind > of problem is registering an object of known dimensions (like a flight case) > full-frame with all of your lenses that are used in a production. This > will give you a much better field-of-view estimation than trying to compute > it with the film back > and focal length. There is always something (some cropping, or a > non-standard lens mount, or other shenanigans) that throw these estimates > off. > > -- > Julik Tarkhanov | HecticElectric | Keizersgracht 736 1017 EX > Amsterdam | The Netherlands | tel. +31 20 330 8250 > cel. +31 61 145 06 36 | http://hecticelectric.nl > > > > > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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