The "crop factor" is described by the sensor measurements you input. Your 18mm lens is still 18mm, no conversion is necessary, your field of view has changed, but not your focal length.. An 18mm lens has a different field of view if its mounted on micro4/3, DX, super35, 35 stills, 70mm or medium format, but it remains an 18mm lens.
Have a play with Nuke's camera node, tweaking the focal length, haperture & vaperture knobs to get a feel for the relationship they have to each other. -Alex On 29/05/2012, at 4:27 PM, Darren Coombes <[email protected]> wrote: Hi, we have some plates shot with the alexa on a 18mm prime lens. I Need to camera track this material. On the Arri website, it says the sensor size for the alexa is 23.76 x 13.37mm when using the ARRIRAW setting with 1.78:1 aspect ratio. in the camera tracker settings, would I put the film back size as 23.76 x 13.37mm? And then I guess i need to find out the crop factor for that sensor size and use that when entering the focal length of the lens? So if we shot on a 18mm lens, and theoretically the crop factor was 1.5 (not sure what the actual crop factor is yet), you would times 18 x1.5? and that would give the right focal length? Can someone point me in the right direction with this? and is my theory of this right? or am i missing something? Thanks. Darren. * * * * * * *Darren Coombes* * * *Compositor* *www.resolutiondesign.com.au* <http://www.resolutiondesign.com.au/> *resolution: sydney australia* tel: *+61 2 9360 9908* fax: +*61 2 9360 8908* *22* burton st: east sydney: *2010* post office box: *614* darlinghurst: 1300* *abn: *3305 196 1856* *2010 Silver One Show Entertainment Award: Online Branded Entertainment * *2009 Gold Promax/BDA Award: Best Broadcast Design Image Spot * *2009 Winner Creative Review Hotshop Award: Post Production / VFX* *2009 Finalist Creative Review Hotshop Award: Broadcast Design* The information transmitted, together with the attachments, is intended only for the person or entity to which it is addressed and may contain confidential and/or priviliged material which may be subject to copyright. Any review, retransmission or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer or network. No warranty is given by the sender that any attachments to this email are free from viruses or other defects. <Unknown.jpeg> _______________________________________________ Nuke-users mailing list [email protected], http://forums.thefoundry.co.uk/ http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
_______________________________________________ Nuke-users mailing list [email protected], http://forums.thefoundry.co.uk/ http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
