Trombone/Vertigo/Jaws/Goodfellas_cafe_scene Shot

[Larry Miles]

Hello.

 

I will be attempting the trombone shot made most famous

in relatively recent times by the cafe scene in "Goodfellas"

where the camera dollies in while the lens zooms out (I

apologize if I have it backwards).

 

When you want to keep a specific subject in focus during a

dolly you can mark points along the dolly whose distance to

the subject is also marked on the focus ring. Is the

relationship between keeping the subject the same size in

the shot to the distance from the subject something that can

also be figured out beforehand?

 

For example, if the zoom angle is X at five feet, can you

mathematically derive what the zoom angle should be at 10

feet in order to keep the subject the same size?

 

I thank you for any help you can give me.