Guideline for determining the range of sharp focus?

[Filmkid2003]

Hey everyone. I am filming with a GH13 and mainly with my 14-140mm Leica lens as well as the 20mm pancake lens. My question is, how do I determine what the distance of sharp focus is when I am setting up the shot and setting up the actor's mark. I mainly need to know this when I have a shot where the actor is either walking towards or away from the camera because I don't have a focus puller. Is there a guide I can download that gives the approximate length of sharp focus AS WELL as the distance from the camera lens that that length of sharp focus starts and ends at. In other words, if I want to have my actor start at ten feet from the camera lens and walk towards the camera six feet so he stops four feet from the camera, how do I determine what f-stop to use that will give me six feet of sharp focus and where I would focus the lens on the actor within that six feet... at the beginning of the six feet, in the middle of the six feet, or at the end of the six feet (which would be closest to the camera lens)? I know that cinematographers used to use measuring tape and run it from the lens to the actor. What are the exact steps for using this method and is it still used today? I know this is something I'm sure I would learn in film school but, I never went to film school so, I'm asking dvxuser. Thanks.

 

[j1clark@ucsd.edu]

Hey everyone. I am filming with a GH13 and mainly with my 14-140mm Leica lens as well as the 20mm pancake lens. My question is, how do I determine what the distance of sharp focus is when I am setting up the shot and setting up the actor's mark.

There are Depth of Field tables for given optical settings and distances to subject and "circles of confusion", the latter is an important element in the calculation and depends on the camera used.

There are online calculators to do this.

I have an iPhone application, called "Toland" which has the GH-1 as one of the cameras supported along with the zoom lens for certain nominal distances. I don't get kickbacks from the producers of Toland, but I think it's a pretty handy way to do these calculations... especially while setting up the set...