keeping subject in focus while they move about

[HerzogisGod]

is this just a practice thing? panning along with a moving subject and working the focus ring....or shifting from one point of interest to another in a room while maintaining focus...

just plain practice? because it's exceptionally difficult with hi-def cams where a fraction either way in focus can spell disaster for a shot.

are there any tips I should know about?

 

[Ryan Patrick O'Hara]

Lay marks onto the floor in desired amount of increments. Then measure the distance/find the focus for each increment and mark the lens.

Now, as the subject travels the path, you can see where he/she is and see if you are on your marks.

 

[NOMADIC]

If there is a dolly push in, sometimes I'll tape marks along the track, or just throw my tape measure on the ground.

If shooting outside, there are alot of things you can get reference from like the distance of the cracks on the side walk.

 

[HerzogisGod]

so you physically mark the focus ring? what type of writing instrument is best to do this? some kind of erasable pencil I assume

 

[DM_rider]

so you physically mark the focus ring? what type of writing instrument is best to do this? some kind of erasable pencil I assume

You don't mark the actual focus ring on the camera. What you need is a follow focus.

http://en.wikipedia.org/wiki/Follow_focus
http://www.redrockmicro.com/mff_product.htm

 

[Barry_Green]

so you physically mark the focus ring? what type of writing instrument is best to do this? some kind of erasable pencil I assume

If you want to make marks on the actual focus ring, use bits of tape like paper tape or even post-it notes. But this will only have relevance if your focus ring is completely repeatable. An ENG lens, or a DVX/HVX/HPX170 will be repeatable, but most consumer or servo lenses won't be.

 

[HerzogisGod]

what do you mean by "repeatable"?

I use an HVX200

 

[Barry_Green]

I mean that when you turn the focus ring to a set position, it focuses the lens to a set distance. Every time.

You cannot do that with a Canon or most Sonys, and you can't do it with any consumer camera. They have vague rubbery lens controls that have no direct correlation. But with a truly manual lens (such as on an ENG camera) or with a true simulation of a manual lens (such as with a DVX/HVX/HPX170) you can place focus marks on the ring and repeat the exact same focus position every time. Only caveat is that you can't turn the rings past minimum or maximum focus distance, or that will throw your marks off and you'll have to re-mark.

 

[NOMADIC]

for making marks on the focus ring, I usually just use a grease pencil, get a white one so you can see better.... it wipes off good and easy :]

 

[pwyll]

Are you talking narrative shoots where you plan the moves beforehand? Or run and gun?

2 very different beasts.