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Pulling focus on a jib


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We had a shot recently with an HPX-500, Pro 35 and Arri 50mm wide open, mounted on a jib & dolly. The shot was for the camera to start behind a couch, float up and over as people parted and land on a shot of a TV in front of the couch. Because of so many moving elements, I devised a way to track the position of the film plane throughout the shot.

 

I hung a piece of rope from an iris rod just under the film plane and weighted it with a grip clip so it hung straight and just above the ground. I then put a piece of tape on the ground at the operator's desired starting position and ending position. As the camera/ jib/ dolly moved through the shot, the rope hanging above the ground easily let me know the position of the film plane to all the action and I could easily pull focus.

 

Pictures:

 

Here's the rope hanging from the film plane above the ground:

P1010032.jpg

 

You can see a few of the distance markers on the ground for the shot.

P1010035.jpg

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Hey Matt, what were you doing on Wayward? I'm trying to put a face to the name. That is Logan, I'll be seeing him for about 2 weeks here at the end of the month so I'll tell him hi for you.

I was the 2nd AC for most of the shoot and I think we only worked together during the motel scenes. You also gave me that piece of rope to tie down my busted spoiler. Much appreciated by the way, I was going to give it back to you but I never saw you for the rest of the shoot days.

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wow Mike, you'd think that you would have put a more flattering pic of me, perhaps one where I'm doing the typical DP pose where I'm looking off into the distance with a smirk of contemplation on my face...

In all seriousness though I must say that the string method was pretty ingenious at the time. Now if we could only figure out how to operate that dolly/jib combo better. Its so cumbersome, too many points of contact. It's good for faster action shots but awkward for smooth flowing shots...

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Brilliant

 

Even with a laser pen you would still need to have it rigged on a string/rope as a pendulum. That way if the camera tilts, the lens is still pointed straight down, rather than moving with the tilt.

Maybe someone can make a hinge like on a Panavision eyepiece extension support so the laser always stays in an upright position...

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Maybe someone can make a hinge like on a Panavision eyepiece extension support so the laser always stays in an upright position...

 

I'd just magnet it to the underside of the crown of the head in this case. You still have to be estimating diagonal distance based on that floor distance and the height of the camera and talent so that will be plenty close to the film plane.

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I appreciate all of these responses but having been a focus puller for 30 years, I must say that these solutions really complicate matters. Of course this is just my opinion. Keep it simple. The job is already complicated enough. The more one can wean one's self away from using marks and simply "see" the distance and "feel" the timing of the focus pull, the easier you will find it gets. Of course a good cine tape helps too! :rolleyes: But with all seriousness, the actors will not always be in the same place relative to the camera and the camera will certainly not be that consistent - especially on a jib. Using a laser is a good idea but again, worrying about the diagonal angles and all that will become burdensome. If you choose to use the laser pen, aim it at the ground from the jib arm, put some simple reference marks on the ground and rely on your judgement after that. You will be amazed how fast your confidence will grow. Once you become too reliant on "marks", especially when the camera and/or actors are not on the marks, you can tend to freeze up and won't know where to go with focus.

 

Best,

Greg

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I appreciate all of these responses but having been a focus puller for 30 years, I must say that these solutions really complicate matters. Of course this is just my opinion. Keep it simple. The job is already complicated enough. The more one can wean one's self away from using marks and simply "see" the distance and "feel" the timing of the focus pull, the easier you will find it gets. Of course a good cine tape helps too! :rolleyes: But with all seriousness, the actors will not always be in the same place relative to the camera and the camera will certainly not be that consistent - especially on a jib. Using a laser is a good idea but again, worrying about the diagonal angles and all that will become burdensome. If you choose to use the laser pen, aim it at the ground from the jib arm, put some simple reference marks on the ground and rely on your judgement after that. You will be amazed how fast your confidence will grow. Once you become too reliant on "marks", especially when the camera and/or actors are not on the marks, you can tend to freeze up and won't know where to go with focus.

 

Best,

Greg

 

Thanks for the advise, Greg! it's great to hear from people like you on this board! I practice the "estimate first, then measure" technique regularly. I hope to get to the point where I can accurately pull focus on a fast lens.

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