Why do they measure the distance between the lens and the subject when shooting a film?
cinematography Measuring tape on set
- Thread starter wparrish24
- Start date
The 1st Assistant Camera or focus puller measures the distance between the subject and the focal plane so that they can make marks on the follow focus and/or lens. Cine lenses (unlike stills lenses) have accurate distance markings on them, which allows the 1st AC to use distance markers to accurately focus on the start and end positions (for example) of an actor, and then estimate the positions in between. Even when markers can't be put down, roughly measuring distances - between the camera and subject, patterns in carpets, between doorways in a corridor - allows the focus puller to pull much more accurately than if they were doing so without.
I'm sure David will have a much more concise answer than mine!
I'm sure David will have a much more concise answer than mine!
David's good, but I don't see how. You did a fine job.
Thanks both of ya, but that answer sums it all up nicely.
Mine would probably have just been twice as long with the same amount of actual information. 
The only thing I'd add is that usually the lens is marked at points that correspond to the measurements, either on a focus wheel, tape on the lens barrel, or sometimes those post-it like sticky darts on big PV lenses (never used these personally) As Chili mentioned though, even just knowing the ranges without exact marks for the talent gives the 1ac something to work with for the pull.