Before you lay down marks, you need a reference point on the dolly itself.
A good place to do this is usually the bolt in the center of one of the wheels on the side you’ll be pulling focus on. If that is still tough for you to see, place a piece of paper tape on top of the wheel or somewhere on the dolly that can act as a point of reference.
Basic Dolly Moves
The most basic dolly move is a push in or pull out where there is a starting position and a stopping position. In this situation, you obviously want marks at the bookends of the move. If the lens is wide enough, you probably don’t need more than that. But if you have the time, or you are pulling with very shallow depth of field, having intermittent focus marks is useful.
Remember that depth-of-field operates on the principal that the closer a subject gets, the shallower depth-of-field gets. So you should place more of your in between marks closer to the subject since there will be less DOF.
For instance, if you are pushing into a landing point, you should have more focus towards the end of the move. If you are pulling out from a subject, most of your focus marks will be at the beginning of the move.
My personal preference is usually to have three in-between marks if I have the time. I place two in the closer half and one in the further away half. I wish I could tell you there is a scientific way of determining where to put them, but I usually just ask the dolly grip to start pushing me from the start of the move and I will stop at different points along the way.
Simply put, I eye it.
Adding More Numbers
More complicated dolly moves might end up having 3, 4 or even 5 different landing points at different times in the scene. This is where having different colored tape is really useful. I will use one color for the marks for the first “1 to 2” move, then a different color for the 3 mark and so on and so forth.
It also helps to write on the piece of tape the numbered order in which the marks are hit. The important thing to remember is not to out-mark yourself into oblivion. The goal is to keep things in focus, not turn the set into a game of Twister.
A crab dolly is when moving side-to-side perpendicular to a subject instead of towards or away from a subject. Generally speaking, these dolly moves are easier than pushing in or out, though there are times when they get complicated depending if you have to rack focus within the scene.
Use the same general guidelines as above and at the very least mark a “1” and a “2.” Even though you are going side-to-side, often the camera operator is panning to compensate for the new angles so you will be slightly further away at parts of the dolly move and closer at other parts.
A dolly can be used similarly to a Steadicam for tracking purposes. The most typical scenario is to have an actor walk towards the camera while it’s dollying backwards. There are also instances where a subject may walk alongside the dolly track while the camera is crab dollying to keep the subject in frame.
Unfortunately with these moves, it is hard to get marks since the movement of the camera is dependent on the movement within the scene by the talent. The best tactic is to use a laser pen to mark a pre-set distance in front of the camera (see below).
In my time camera assisting, I’ve picked up on a few tricks that I’ve seen other camera assistants use. Some of them are “out there” while others are really ingenious. Here are the ones that I think are good to have in a repertoire:
The Lead Up
Sometimes it can be tough to see tape on the ground or there is no real way to gauge how fast a mark is approaching. This method helps you know not only where a mark is, but when you will be reaching it.
You take a long piece of colored tape and angle it starting far out from the tracks and into the mark. As you are approaching your mark on the dolly, you will be able to watch the tape “close in” on the mark and be able to pull focus appropriately.
The Laser Pen
This trick is best for when the dolly is used to track with a subject. You mount a laser pen to point a pre-selected distance on the ground in front of the dolly (i.e. 5 feet) so that you know when a subject is closer or further away than that distance at all times during a move.
The C-47 Hang
For those who have trouble recognizing their own marks while on the dolly and where exactly the reference point to them is, you can use a versatile C-47 to help you out by hanging it from the dolly. This acts as your reference so that when the C-47 hangs over the tape, you are on your mark.
What’s Your Method?
Dolly moves are one of those areas of camera assisting where every person will have their own way of doing things. They can be both challenging and a lot of fun if you know how to approach them right.
So what techniques do you use? Do you ride the dolly or walk alongside it? What kind of advice would you give for those who aren’t sure how to approach marking a dolly shot?