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Pulling Focus Tips


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Do you recommend this book? Or did you just find it in a search on Amazon :)

 

can't say that I'd recommend it. I picked it up once in a shop and couldn't believe someone had written a whole book about what to eat, how drinking soft drink onset means you have a sugar crash at 2pm and how to meditate...except all for focus pullers. I guess it was all true....It was all the "zen" references in this thread that made me think of it.

 

I was always a terrible focus puller. Didn't last long.

 

jb

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Ooh, I'm so glad someone else mentioned this book! I read the Optics & Focus book cover to cover...I used to bring it to CSC when I worked there, and I'd read it during lunch and everyone would be like, "What the hell is that?" For whatever strange, geeky reason, I actually really enjoy this book. I think because within all the scientific jargon about optics (which IS interesting!), there's also some really solid practical advice that you don't hear much about, but is totally valid when it comes to being a good AC and being ready for anything. When I go on a job now, I pay more attention to the simple things...physical things like my own comfort, if I'm tired, if I'm thirsty or hungry. All of these things affect your performance. If you don't believe me, observe the crew when they've gone into their third meal penalty! Or try pulling focus when you're freezing your ass off and pissed at everyone...I think it's worth that extra level of self-awareness. Part of why I love what I do is because it has really touched me on a deeper level, in a way that almost feels spiritual sometimes...quite Zen. :)

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One thing I find helpful when pulling is to practice without looking at a monitor or viewfinder. Obviously a lot more practical to practice with a digital camera and a 35mm adapter set-up. If you have a set-up of your own or know someone who does. This is a lot more helpful with static camera shots and CU's I find. Get your subject in critical focus(with the help of a monitor of course), turn away from that monitor, hit record and start pulling(with the subject moving around at varying distances and speeds). Play it back, study the shot, repeat to correct mistakes and do it all over with different focal lengths and such. I find quite often on lower-budget shoots that there is no hoodman or flag available for avoiding glares / flares on the monitor, which kinda makes it harder to see if you're in focus or not(sometimes you only have one moment to check initial focus before a given shot). This way you are more intuitive at focus pulling. It helps too when pulling from the barrel and you have no time to create marks for various reasons, helps in a pinch.

 

-Benjamin

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  • 3 months later...

FIrst off, I thought that the 35mm adapters projected an image onto another piece of glass which the camera then records. SO I would think that the CoC would be calculated for the size of the screen and lense setup, not the size of the XL2's 1/3" CCD. Granted you will pick up less detail with SD CCD's, if blown up, you would definately see if the image was soft.

 

Secondly, I'm really confused now. Stephen says that depth of focus and depth of field are inversely proportional? So are you implying that these are two seperate things? I have always thought that the two terms were one in the same???

 

I think I see what you mean. The Depth of Field is the amount of distance that the subject will be in focus, but the Depth of Focus is the actual mechanics implied to rotating the barrel of the lense to find your sharps? In other words, the closer an object, the less depth, therefore the more you have to rotate the lense to find focus? That would be inversely proportional.

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Secondly, I'm really confused now. Stephen says that depth of focus and depth of field are inversely proportional? So are you implying that these are two seperate things? I have always thought that the two terms were one in the same???

No, the term "depth of focus" refers to the image projected behind the lens (ie. at the focal plane), where the plane of focus becomes increasingly critical at wider focal lengths. As the depth of field increases in front of the lens, the depth of focus behind the lens decreases - they are inversely proportional. Therefore, wide angle lenses require stricter tolerances for collimation than do telephoto lenses. Now that I think about it, this is probably one reason why back focus on a video lens is adjusted mainly at the wide end of the zoom, it's the inverse of how you'd focus on a subject in front of the lens. Hmm, back to the books!

 

http://en.wikipedia.org/wiki/Depth_of_focus

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Thanks for the clarity Satsuki. I guess I never really thought about it.

 

With regards to the Zen, I sometimes find myself in a really intense concentration whilst pulling for a shot. I had an operator ask me the other day if I was pissed off at something because I was concetrating so hard on a shot, I was frowning and didn't realise it. Although it was 1600, and we hadn't even had lunch yet. Maybe that had something to do with it.

 

I have ruined a take before with a stomach growl... RooooaAAR!!!

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I've seen Focus Pullers use cheap DV cameras at 90 degrees to the action. It then feeds a small monitor by the Main camera. As the camera is side-on to the actor, it clearly shows how much they are leaning in or out, and these distances can be marked on the monitor screen with a whiteboard pen.

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I've seen Focus Pullers use cheap DV cameras at 90 degrees to the action. It then feeds a small monitor by the Main camera. As the camera is side-on to the actor, it clearly shows how much they are leaning in or out, and these distances can be marked on the monitor screen with a whiteboard pen.

 

That's a pretty good idea if you're doing a lot of stuff with that "ears soft" kind of DoF.

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I've seen Focus Pullers use cheap DV cameras at 90 degrees to the action. It then feeds a small monitor by the Main camera. As the camera is side-on to the actor, it clearly shows how much they are leaning in or out, and these distances can be marked on the monitor screen with a whiteboard pen.

But how often is this really practical? Very seldom I think.

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I've seen Focus Pullers use cheap DV cameras at 90 degrees to the action. It then feeds a small monitor by the Main camera. As the camera is side-on to the actor, it clearly shows how much they are leaning in or out, and these distances can be marked on the monitor screen with a whiteboard pen.

 

Kinda ridiculous, IMO

 

Setting up another camera, monitor and making your markings on a TV screen? That's definitely overdoing it, and at the expense of others.

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Kinda ridiculous, IMO

 

Setting up another camera, monitor and making your markings on a TV screen? That's definitely overdoing it, and at the expense of others.

 

It's not something I've seen often, but it has it's uses. The last time was on a shot of a man conducting an orchestra. It was a 135mm lens at around 12 feet, and quite a wide stop. The conductor was of course moving around a lot, swaying with the music. Thanks to this little setup the AC had it about 95% sharp.

 

Which takes more time? 2 minutes setting up a little camera or extra takes for focus?

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Which takes more time? 2 minutes setting up a little camera or extra takes for focus?

In the situation you site, it sounds like a useful solution because it seems that the camera was in one place for a long time. In most situations the camera moves from setup to setup and is very rarely in one place for very long, which makes using an extra camera a time strain, and therefore not very useful in most situations. But I can see it being useful when you know the camera isn't moving for a long time....in that case I can see it being worth the extra time if you know it will work for you.

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I would think that using the remote focus whilst standing on the actors profile would be a much more efficient and accurate way of measuring the actors forward and backward movement. I would think that any DoP would be nuts to try and hinder a focus puller's work as long as it produced sharps. It's always good to stay close to the operator or DoP, but you gotta do what you gotta do.

 

If I'm on a dolly, I use a little laser pointer and measure the distance between the camera and the 'dot', so that I have a rough idea when the actor is closer or further. I just grip it with a magic arm onto the front of the dolly and voila! If I was really anal, I could use two laser pointers to mark in and out or two 'grace' measurements.

 

This doesn't work on a bright day though as it's hard to see. So I use a stick off the side of the dolly, tied to a piece of string or tape that drags an exact distance from the camera. I can then mark on the tape the incremental distances from the camera.

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The little DV stuff can be useful, but there is a human version of this : the second assistant ^^

 

You put your second at 90°, with a fix stick (like a C stand) on which he had put some marks with a tape, and he moves his finger on this stick, following the object of focus. The first, quietly sitting next to the camera, looks at the position of the second's finger, and here you got your human DV solution ^^

Edited by Nicolas Eveilleau
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In the situation you site, it sounds like a useful solution because it seems that the camera was in one place for a long time.

 

Sure, it's not something that would be possible in every situation. It's just another little trick that sometimes helps you out, but I think the original post was about a similar situation.

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I like to press a yard stick up against the actor's chest, and I pull as the measurements slide past the focal plane, impaling the operator ;)

 

Screw all that. Tie the talent to a chair and be done with it.

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What would be cool, is if they invented some sort of goggles that the focus puller can wear. In the center of the view through the goggles, there would be a crosshair. SO basically, whatever the focus puller was focused on, the goggles would emit an infra red signal to the subject and back giving a highly accurate distance reading to the camera's auto focus unit attached to the 19mm bars.

 

Kinda like auto-focus but a bit more sophisticated. It would kinda take the fun out of the job, but at least you could use it for really tough shots that would basically be impossible otherwise.

 

Bit geeky I know...

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What would be cool, is if they invented some sort of goggles that the focus puller can wear. In the center of the view through the goggles, there would be a crosshair. SO basically, whatever the focus puller was focused on, the goggles would emit an infra red signal to the subject and back giving a highly accurate distance reading to the camera's auto focus unit attached to the 19mm bars.

You're basically describing a Cinetape or Panatape. Of course those aren't auto focus though, and you don't wear goggles...the readout is mounted right on the mattebox.

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You're basically describing a Cinetape or Panatape. Of course those aren't auto focus though, and you don't wear goggles...the readout is mounted right on the mattebox.

 

Technically the readout is a perfect feedback system to go to a servo, though. The downside is that they're ultrasonic. The outlandish thing I've been thinking about is this: Have some form of eye-tracking technology (there's a bunch of different types now) controlling a pitch/yaw-axis deal aiming the Sniper barrel...then feed that to a modified FIZ. viola! autofocus.... just dont look away.. lol. :P

 

The other option would be to aim the Sniper manually with the help of it's reference laser, but time the laser to the camera's shutter pulse so it only fires in between exposures. I think it would be really easy, but haven't heard of anything like this yet. Has anyone else?

Edited by Matt Kelly
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  • 1 month later...

Someone mentioned sitting near the lens, well you have to sit close and behind the lens so your look to the lens can be just a glance, if you need to turn your head, youre screwed because in that time the subject will have moved.

 

I also try to use the FF witness mark (the movable one) as a finger stop on the end of the pull.

 

But an 85 wide open on the mini 35 adapter with a close subject is going to have very shallow depth, so 1 to 1-1/2 stops isnt going to grow that depth that much that the background wont still fall off in focus. And if it means not getting the shot the DP should at least try to give you a fighting chance with a little extra stop.

 

I know thats not the answer to the question, but most DP's know better and if he puts you in a position to not get the shot, its also his problem. Remember we function as a team win as a team lose as a team.

 

Joe C

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