Pulling focus on the DVX sans Follow Focus?

Shawn Murphy

Shawn Murphy

Well-known member
I'm looking for footage (or first hand accounts of success/failure) from anyone who has worked with an AC/puller/(or friend), pulling focus on the DVX without a dedicated Follow Focus attached and with moving actors (and obviously with a shallow depth of field, otherwise they're wouldn't be a need to pull focus).

*If I had access to more willing participants I would try it out now, but I don't have the humans handy, and I also wanted to see some footage from some DVXUSERS that might have already experimented (or perfected!)

**I'm also open to footage and accounts of anyone who has a DVX with a Follow Focus attached.

Thanks in advance.
 
I've done both, and both have been successful. The main reason why I love/own the DVX100A is those funny little z numbers on the viewfinder. They don't seem to mean anything concrete, but they do allow for flawless focus pulls. Once you practice a bit and get the hang of where on a, say, 10 foot scale those numbers put you, you can pull focus like a pro. Also, an on board LCD monitor helps out a bunch, though I've done two films, both as 1st A.C. and as D.P. where we did on the fly focus pulling without a monitor and we had no focus problems. On thing I may suggest is popping over to http://store.yahoo.com/cinemasupplies/laspoinandcl.html and checking out the laser pointer rigs they have on there. You can rig the laser pointer which is attached to a mini-cardellini clamp, to be set to a certain distance from the lens on the floor. This gives you a starting point from which to determine where object are in the field. Those things are damn useful for both handheld, and for dolly work. They are worth the pricetag.
 
profnoxin Thanks for the feedback, as with most things you get out of it what you put into it, so, I'll try and get some practice in both as a puller and operator.

I did the tape measure approach on a recent shoot of a theater/stage/one man show, and although I thought for sure I could rely on infinity MF95, when I did that it didn't look in focus throughout the range of movement the actor had on stage, which ranged from ~10 ft - ~15ft. So, I tried using the chart numbers from Barry's book, and it looked as though I would need to float between ~MF77 - ~MF83, anyhow, in the end I ended up soft in some of the farther shots, but I still can't figure out why it was soft. I was at Z00, F3.4, which I thought would give me the widest DOF (everything in focus?).


Not sure I follow how you use (take advantage of) the laser setup, I can Google it or if you have a moment perhaps you can elaborate in newbie/layman terms.

Thanks again.
 
Shawn Murphy said:
profnoxin I was at Z00, F3.4, which I thought would give me the widest DOF (everything in focus?).
Click to expand...

F3.4 is still a pretty open aperature with a fairly shallow DOF - it's certainly not the deepest, of course. If you need more DOF, stop down one or two to a 5.6. If you want almost everything in focus, stop down a hell of a lot more to 11 or more.
 
dustino Thanks for the info, I'll brush up and read the DOF tutorial again as I've obviously overlooked the significance of the aperture.

So, does this mean that the "infinity" value really only occurs within a certain aperture range? *perhaps my answer is in the tutorial, I'll go and do my homework now! ;-) Thanks again.
 
profnoxin,

Could you elaborate further on exactly how to use those little z numbers to pull focus? Also, could you explain more about how the laser pointer and clamp work to achieve good results?

Any others with experience and thoughts in pulling focus on a moving subject ... mistakes, learnings, wisdom and all?
 
One of the problems with relying on a wide angle lens for your shots staying in focus, is that all of your focus is going to be a little soft. When things start straying from the hyper-focal distance of the lens, you are going to get a little bit of softness in the edges. The Z numbers are randomly assigned numbers that do not corrilate to meters or inches or feet or yards, but you can use them to do a precise focus pull. The easiest way to set focus is to zoom in on your object, and if you want, have you assitant take a mag lite, pull the cap/lens completely off, and hold that in front of your target. When you focus the lens flare into a pointed star flare, you have perfect focus to that object. Look at your Z number. Say it is 22. Then your subject walks somewhere. Take an end focus mark, do the flashlight trick again, and your number is Z 37. You now know that you need to pull accrodingly between Z22 and Z37. If your subject makes stops, or has a long move, you can take multiple marks along the way, and mark the floor with Focus Bags (Look on www.filmtools.com if you are not familiar with these) or with paper tape, and figure out what all of your Z numbers are along the way. I will try to post more on the laser pointer, but this is somewhat difficult to explain in writing without any sort of visual aid. Until then, hopefully this will help you. If you want tighter focus, move your camera further away from the subject and zoom in for you tight shot. It will narrow your depth of field, but will give you the ability to have some sort of sharpness to your image.

Also, a tip to always remember is that on the focus ring, moving it to the right is for closer focus, moving it to the left is for further focus. On a follow focus, from the bottom of the ring, forward is forward, and backward is for close focus. As I said, more later on the laser pointer technique.
 
Justin,

Thanks for the info, and look forward to the laser follow up. Marking and measuring will become more and more a staple of my setup process, particularly when the DOF is shallower than "infinity". I also did the zoom/focus, then frame approach, but the main thing I overlooked was the effect the aperture has on the DOF, not a problem in a high light scenario, but with lower light situations I guess you have plan on adjusting focus for the duration of the entire show! A live show is not the same as shooting scenes for a fictional piece scene by scene, this would have been an hour and a half of floating between 77 and 83 as the actor moved from side to side of the stage (and the distance was made worse by the fact that we had to shoot from an angle, off center form the stage).

Thanks again for the tips.
 
Make that a DOUBLE THANKS, Justin.

Appreciate your taking the time to explain the moving focus issue. It is a little dense, though. But it sure helps when folks like yourself make the effort to make the topic simple and transparent.

Looking forward to your next post on this subject.
 
Here is the promised follow up to the laser pointer issue. I will try to be as lucid as possible without the use of images...

There are a number of ways to mount the laser pointer to the camera. The easiest is if you have a base plate with iris rods, the clamp can clamp on directly to them, otherwise, some type of make-shift rig must be employed... The laser pointer is then pointed at a desired angle, shining diagonally down and forward from the lens, projecting a dot, say ten feet in front of the lens. First, you must measure the distance from the "film plane" or rather, "the CCD plane" (which is wherever the CCDs are located within the camera. On most film cameras this is marked by the image of an "O" with a vertical line through it, on the DVX, to my knowledge, and I may be wrong, you need to rough in a guess as somewhere directly behind the actual lens housing) Then, once you know your Z mark distance, you can move forward....

With the knowledge that the dot projected on the ground is at roughly, say, Z25, you know that even if both you and your subject are moving, that when they are around that dot on the ground, they are at Z25. From there, you can rough in pulling, straying anywhere from Z20-Z30 if they get closer or further from the dot. This is most especially a useful technique for handheld, and especially when the Director (Or 1st A.D. (or even worse - The Producer)) is telling you that you need to get the shot, and get it now.

This technique can also be applied when you are doing a Z Axis dolly (Forward or Backward) from a subject that is moving toward the camera. Set the dot at the desired framing distance, and if the actor slows down or speeds up, you can adjust the focus. Also, your dolly grip can look at the dot, and they will know what speed they need to match, as you generally set the mark at the actors feet. When working with a dolly, you can mount the laser pointer to the push bars, to the front of dolly, etc. etc.

In closing on this novel of a post, I hope that this is helpful to you. If you master this, you will save yourself the agony of re-shooting over and over again because of lost focus. Once you get good enough with the laser pointer, you'll probably be able to ditch it, and just focus by eye. I find that often times using the laser pointer puts A.D.s and Producers at ease a bit - It's like shorthand for "I know what I'm doing".

Enjoy,
 
Justin,

Thank you very much for that lucid explanation. You are clearly a DVX Master.

If at some point you feel inclined and especially generous, I'd love to see a visual representation of what you described. Due to my certified low IQ level, I tend to understand better with visuals ... especially with the nature of this laser focus topic.

Thanks again for your kindness.
 
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