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class="style14">Motion Control Without The Control

>Published : 8th Nov. 2006

>I want a "motion control" shot but I can't afford a mo-co rig. Can I cheat with some careful dolly work and some cheating in post production?

>Here's the shot (it's a corporate video) :

>The aim is to quickly illustrate that an industrial vehicle can be loaded with either logs or a machine or people. The camera will circle the vehicle and as the camera tracks round the vehicle, the vehicle's load will magically change.

>All I have is some circular track and a dolly so I can't guarantee that the camera will by moving at exactly the same speed for each "load".

>Will I still be able to cross-fade between the shots to give the impression that the load is magically changing? If not, can I use After Effects to "smooth" the transitions?

>Any hints would be fantastic!

>Thanks,

>Jack Kelly
London
Dir/Prod/Camera
UKFilm.org


>Hello Jack,

class="style15">>All I have is some circular track and a dolly so I can't guarantee that the >camera will by moving at exactly the same speed for each "load". Will I >still be able to cross-fade between the shots to give the impression >that the load is magically changing?

>In the "olden" days this type of shot would be accomplished with a good dolly grip and the use of a timing mechanism like a metronome.

This can also be accomplished with pixilation and marks on the dolly track so the camera position can overlap exactly. That is if the object is in a nodal position vis a vis the camera and lens. And I'm sure it can be smoothed out. I did a Merle Norman commercial years ago where we did before and afters of women. Sounds easy enough except the turnaround on the make-up was about 2 hours and we had to shoot different women without make-up and then made up. It's not hard, just picky. Have fun with it.

>Kind Regards,

>Mark Woods
Director of Photography
Pasadena, California


class="style15">> I want a "motion control" shot but I can't afford a mo-co rig. Can I cheat >with some careful dolly work and some cheating in post production?

>I once did a similar shot around a piano. There was green screen and the player would disappear but his white gloves continued to play on the keys.

>This was a while ago and whatever jury rigged "motion control" rig that we had wasn't working so we tried it on the fly, so to speak. It worked out very well...well, sort of. But I recall that the post fellows said they had enough to work with and they made it happen.

>If you can slowly pan and keep the cross hairs on one spot each pass that would be a big help to post. Also, is the circular track that you have big enough for your industrial vehicle? I would think that the more distance that you have the better/easier the match/dissolve. Lock the tilt and in a perfect world if you could lock the pan then you're 9 tenths of the way there. As far as the speed of the move is concerned, maybe it's ok to vary it- have it speed up.

>Maybe you could use the lack of control to your advantage by creating something different. People will ask, "How did you do that?" Well...I'd do a lock off of the changes to cover myself. I bet you already planned to do that. Support the vehicle underneath to prevent movement from the different weights. What if you locked off the camera and had the vehicle drive towards and pass by you at the same speed each time.

>Already done that? ok.

>Gee, if you had a giant lazy Susan...

>Good luck, have fun.

>Edwin Myers,
Atlanta DP


>This shouldn't be too hard in After Effects. If you really must use a dolly, then you might consider picking up a cheap speed gun from Radio Shack to make sure the dolly is rolling at the same speed on each pass. That's the most important part, that there are no drastic speed changes. If you keep each shot within 5-10% of the speed of the other shots you shouldn't have too much trouble doing a speed change on the footage. The most important thing is that the dolly operator keeps a consistent speed.

Josh Brown
New York, NY


>I meant to say a consistent speed within each pass. There can be a little variation between the passes, but that's also best kept to a minimum. I've done similar shots with manually driven rotations, and the biggest problem was adjusting for slow downs and speed ups within the pass.

Josh Brown
New York, NY


>Edwin Myers writes :

class="style15">>It worked out very well...well, sort of. But I recall that the post fellows said >they had enough to work with and they made it happen.

>The post production effects guys can make miracles happen, but would much rather you made their life a bit easier. They hate the term "fix it in post" and would much rather you "fixed it in pre".

>The latest software does amazing tracking, but you can save a lot of
time and money by thinking the shot through very carefully and getting the CGI guy in at the start, since he/she is the one that will ultimately know how to make the effect work well.

>Clive Mitchell
http://www.bigclive.com


>Many years ago we attached a *friction-drive* to a dolly to maintain a constant speed move for a science show opening sequence where foreground objects kept changing relative to a constantly moving common B/G.

>This *hi-tech* device consisted of a servo motor driving a shaft- mounted skate board wheel pushed down on to the track by a heavy spring. The outrigger motor was fixed to the rear of the dolly by a couple bits of sturdy timber and G clamps.

>The servo motor was a stand alone device with its own power supply and speed controller. It worked!

Check that you have adequate distance around your vehicle as a typical circular track can have about 20 feet/6.00 metre outside diameter.

Cheers,

>Matt Butler
occasional moco person
Sydney, Australia


class="style15">>>"I want a "motion control" shot but I can't afford a mo-co rig."

>Shoot your secondary shots looser than the standard, so you have punch-in room to match. Scan 4K if you can, 2K at least (for HD finish).

>Tim Sassoon
SFD vfx & creative post
Santa Monica, CA


>Jack Kelly wrote :

class="style15">>>All I have is some circular track and a dolly so I can't guarantee that the >>camera will by moving at exactly the same speed for each "load".

>A good grip should be able to repeat the move pretty much over the same time - OK not exactly but you could then speed up or slowdown in post.

>What I have done in the past for something similar was to place equally spaced markers on the track and give the grip a walkman and headphones or with a recorded countdown playing into the grips ears, then they just pace themselves along the track to hit the markers.

>Michael Sanders
--
Director of Photography/Lighting Cameraman
London UK.
Online showreel at http://www.glowstars.tv/