Focus while dollying

P

Peter Reynolds

Well-known member
Hi there.

I recently used a dolly with straight track for the first time and I had some trouble with focusing. The shot called for us to dolly toward our actor as he talked on the phone.

I tried focusing on the subject up close, then move back 10 feet and dolly in. However from 10 feet away the wide shot looked rather soft.

This technique works if I'm zooming, but I'm wondering if there's something else I should be doing for a dolly shot.

Any suggestions you may have would be great.

Thanks.

Peter
 
Hi Peter,
I actually haven't done a dolly yet. Pretty new myself. but other than changing the focus on the camera lense while moving in, you probably won't get a good focus especially in HD.
The thing to use is a Follow Focus device which brings the focusing ring to the side of your camera. You would also use a whip cable. (basically there is a gear with teeth that goes around your focusing ring on the camera. Then there is a dial on the side of the camera attached to a rail system under your camera. the dial has teeth also and when you rotate the dial it moves the focus ring on your lense.) The whip lets you pull focus without putting your hand on the camera (on the follow focus dial) so as not to move the camera.
also some tips:
when wide angle the depth of field is larger (more things are in focus)
and also when your Iris is closed the depth of field is also larger. (so put a lot of light in your scene and compensate by closing your iris . ie f-stop 11)
This should help.
 
When zooming you don't actually change the distance to your subject. So you focus the lens at, say, 8 feet and then you zoom, well, you're still at 8 feet away so the focus stays constant.

When dollying, you're actually getting closer to the subject, and that means you have to adjust the focus throughout the shot (aka "pull focus").
 
Auto focus only when there is nothing in the foreground but if there is nothing in the foreground, that makes you shot uninteresting and flat.
 
Thanks

Thanks

Thanks for the advice everyone. Barry, that was a very clear explanation of dolly vs. zoom. Really terrific.

Now, just to confirm. For a dolly shot from 10 feet to 2 feet, I would do the following:

1. Focus at 2ft and mark it (either on a follow-focus device or with a piece of tape on the focus ring).

2. Focus at 10ft and mark it (once again on either a follow-focus device or with a piece of tape on the focus ring).

3. As I dolly from 10ft to 2 ft, have someone (i.e. the focus puller) gradually move the the follow focus device or focus ring, from the first marked position to the second marked position.

Is that correct?

Thanks again.

Peter
 
Thats basically correct, but Im sure you want to stay in focus between 10 and 2 feet?
 
Your pull has to change incrementally in relation to your subject. Think of the move as a series of locked-off shots with their own distinct marks.

A good focus puller, who also has some familiarity with a given lens, should be able to keep focus through the move at almost any speed.

A good follow focus unit will allow a more accurate pull in several ways:
  • Setting hard stops at either end of the move (e.g., 10' and 2') provide a margin of safety for the focus puller - even if they come off the rehearsed move at either end
  • Additional focus marks on the disk, which correspond to spikes (or other landmarkds) give a quick visual reminder of where the assistant should be within the range
  • Speed cranks can be set up for extreme focus pulling situations (e.g., rapid compound moves)
  • Repeatability. With the hard stops, you can effectively defeat the infinite focus rings found on Canon, Sony and Panasonic pro-sumer cameras. Marking the lens barrel with tape or a china marker won't prevent you from over-cranking it and the loss of calibration.
e
 
Thanks. Great advice.

I'm going to be purchasing the Canon A1 in January.

NCJE - which follow focus would you recommend for the Canon?

Overland Films - I'm not sure what you mean by "Speed Cranks".

Also, when you say "Hard Stops", is that something physical stopping the focus ring, or just a pen mark on the follow-focus? If it's just a pen mark, I don't see the difference between that and two pieces of tape lined up on the focus ring.

This is all very informative. Thanks again for all your help.

Peter
 
The speed crank is a 90° "L" shaped arm which attaches at the center of the follow focus, where you would attach the extension whip. It offers a little more leverage and speed for larger focus shifts.

The hard stops are done a little differently on each system. On most, they are small metal clamps that affix to the marking disk, stopping the disk as they hit the marker tower.

e
 
Me Myself & I said:
Thanks for the advice everyone. Barry, that was a very clear explanation of dolly vs. zoom. Really terrific.

Now, just to confirm. For a dolly shot from 10 feet to 2 feet, I would do the following:

1. Focus at 2ft and mark it (either on a follow-focus device or with a piece of tape on the focus ring).

2. Focus at 10ft and mark it (once again on either a follow-focus device or with a piece of tape on the focus ring).

3. As I dolly from 10ft to 2 ft, have someone (i.e. the focus puller) gradually move the the follow focus device or focus ring, from the first marked position to the second marked position.

Is that correct?

Thanks again.

Peter
Click to expand...

Peter,

Basically, yes, but I don't think the focus ring itself provides for repeatable focus pulls. It's not mechanical, it's electrical, so you won't really be able to mark it and move it from point A to point B and get the same focus every time. Someone correct me if I'm wrong here.

What you can do is the use the focus number readout on the display. Note the focus number on the wide and the tight shots and practice moving the focus between the points as you dolly. You can't beat practice.

If you can get a remote focus device, like the Foxi, and you have someone monitoring, they can do this adjustment remotely.

I used a technique you metioned, adjusting focus for the end of the shot and then just dollying in to it. It can work, but it depends on what your zoom setting is. If you are zoomed in, it won't work because the depth of field is too shallow. However, if you are working in a wider shot, and you aren't dollying too far, it can work really well. It's a cheap trick.

Josh
 
the hvx and dvx rings are completely and totally repeatable as long as you dont focus "past" the available range
 
When I worked on THE CASINO JOB, the director wanted a to use the dolly in almost every shot.

The DVX is a tough little camera to rack focus on, especially when you are moving on a dolly. We had many a frustrating moments to say the least.

Because we didn't use an external focus wheel, I ended up either using the auto-focus feature (sparingly and if there wasn't much in the shot), or I would do my move several times. noting the focus numbers in the viewfinder. It definitely wasn't precise, but it ended up working pretty good. It also forced me to practice the move, so when we rolled, we got the shot in a couple of takes.

This helps save money, even though tape is cheap, everyone's time and patience is not.
 
The DVX is completely repeatable and easy to pull focus on. We usually just put a tick of tape on the ring at the start and end points, and rack from there. Focus puller should be riding on the dolly and watching the LCD panel from the side of the camera, while the operator uses the viewfinder.
 
Me Myself & I said:
NCJE - which follow focus would you recommend for the Canon?
Click to expand...

I havent tried one on the A1 as yet, there are many recommendations on the forum and price variances. You need to check your budget then those that fit within it.

Either way you do it, you will need a focus puller. Without a follow focus on the A1 I would use the A1s metering system.

So check your focal distances at points along the move and mark them alongside the dolly so the focus puller knows when he should hit 9,8,7,6,5,4,3,2 feet.
 
Barry,

Yes, but as smelni says, the focus is continuous, so if you overshoot past 99 or below 0, then your marks are no longer valid. So you have to be real careful.

Josh
 
Joshua Provost said:
Barry,

Yes, but as smelni says, the focus is continuous, so if you overshoot past 99 or below 0, then your marks are no longer valid. So you have to be real careful.

Josh
Click to expand...
Well, yeah, but if you've marked your start & stop points with tape -- I dunno, I find it extremely easy...
 
You must log in or register to reply here.
Back
Top