View Full Version : How do I do this focus trick?


Kyle Field
June 14th, 2004, 03:07 PM
While watching HBO's Deadwood last night I noticed that they really like to focus on something in the foreground and then change the focus to and object or person in the background as a character comes walking in. Neat trick to direct your attention to the subject (and they do this A LOT).

Is this possible with the GL2? I just got mine and haven't had a chance to play with it due to my 2 month old daughter. Just wondering, is it as simple as using the manual focus ring and adjusting as desired, or is there more to it?

Thanks for your time.

Ken Tanaka
June 14th, 2004, 03:30 PM
Kyle,
I have not seen that show, but the technique you've described is called "rack focus". That is, shifting focus to a different point in the depth of the frame.

It -can- be done with the GL2 but is a bit of a challenge due to the lens' servo-driven focus ring. It's quite simple with a fully manual lens, such as the one available with the XL1S or the lens on the DVX100A. These lenses enable exact adjustments to focus.

But, even in full-manual focus mode, the GL2's focus ring is driven by a motor as you turn the ring.

So basically, it will just take some practice and generally at least a couple of takes. Lock the camera down, keep a wide aperture (to thin your DOF) and position the camera a ways back from your subjects.

Enzo Giobbé
June 19th, 2004, 10:29 AM
<<<-- Originally posted by Kyle Field : While watching HBO's Deadwood last night I noticed that they really like to focus on something in the foreground and then change the focus to and object or person in the background as a character comes walking in. Neat trick to direct your attention to the subject (and they do this A LOT).

Is this possible with the GL2? I just got mine and haven't had a chance to play with it due to my 2 month old daughter. Just wondering, is it as simple as using the manual focus ring and adjusting as desired, or is there more to it?

Thanks for your time. -->>>
Is this possible with the GL2? I just got mine and haven't had a chance to play with it due to my 2 month old daughter. Just wondering, is it as simple as using the manual focus ring and adjusting as desired, or is there more to it?

Thanks for your time. -->>>


This is an excellent site with lots of really great information! (Found it while doing a Google.It search.)

Rack focus on a GL2 (one method):

First, you'll have to shoot wide open, as the DOF with 1/4" chips is very deep as it is. You will want to keep your shutter speed at 1/60, so use a ND to get the proper exposure with the lens wide open (f. 1.6 to 2.2). Unless you're shooting under very low light, the GL2's built in ND will not be enough.

Use the camera's zebra function to check your exposure (on Caucasian skin with the GL2, an 85 or 90 zebra setting should show small hot areas on the specular highlights of the faces if the exposure is correct).

Next, switch over to manual focus and using at least a medium telephoto setting (or longer), block your actors so that one actor is fairly close to the camera, then block the other actor so that he/she is at least 6 to 8 feet away from actor 1 (the farther the better, within the confines of reality and what effect you are trying to achieve).

Now, get some 1/4" or 1/8" camera tape (thin masking tape will do), and set the focus on focus point 1. Then place a piece of tape on both the focus ring and the GL2 lens housing. That is your focus one mark.

Now (carefully) focus on focus point 2 and mark that spot on the ring with tape. You should now have two marks (tape) on the rubberized focus ring, and one mark (tape) on the body.

Start your shot on focus mark one, and then have an assistant "rack" the focus ring to focus mark two. You can go back and forth, but redundancy does have it's pitfalls.

Be careful, as it's very easy to overshoot the mark either way and reset the manual focus to null. A few practice runs should give you a good idea what kind and how fast a movement will be required to "dial in" the shot.

You'll want the camera on a good set of sticks, and set the GL2 to tape off, not camera off for standby mode (if the camera goes into standby at the camera off setting, it will probably screw up your focus settings/marks).

Remember not to move the focus ring too far either way, or you will loose your dialed in focus marks, and have to recalibrate.

Having the action too far from the camera, the lens set too wide, a deep stop, or the focus points you want to rack between too close, will defeat the effect you are looking to achieve.

It's not the easiest thing to do with a GL2 (or any small chip DV camera, even if the lens is hard calibrated with a focus/ft./m. scale), but it can be done, and done to great effect.

Next, you'll want to try racking between a stationary object and a moving one, or two moving ones (even going in opposite directions), or even racking to multiple focus points in the frame.

Have fun!

Enzo Giobbé

Jeffery Patch
June 26th, 2004, 01:53 AM
kind of off topic but I was on the episode of Deadwood AFTER the one you are talking about :)


http://www.deadwoodfans.com/forum/viewtopic.php?t=11

Alex T. Hurter
June 26th, 2004, 04:56 AM
<<<-- Originally posted by Enzo Giobbé :
This is an excellent site with lots of really great information! (Found it while doing a Google.It search.)
Enzo Giobbé -->>>

do you have a link to the site?

Enzo Giobbé
June 27th, 2004, 03:50 AM
<<<-- Originally posted by Alex T. Hurter : <<<-- Originally posted by Enzo Giobbé :
This is an excellent site with lots of really great information! (Found it while doing a Google.It search.)
Enzo Giobbé -->>>

do you have a link to the site? -->>>

Hmmmnnn... Sorry, I must have been thinking in Italian when I was writing in English.

I meant THIS site is an excellent site (I found DV Info Net off of another page link while doing a Google search on another topic).

The rack focus tip is strictly mine, and the only place you will find it posted is here on DV Info Net (but is a pretty standard method of achieving the effect with focusable lenses).

Sorry for the confusion.

Enzo Giobbé

Alan McCormick
June 27th, 2004, 11:51 AM
I can get the "pull focus" but only if I zoom very close to the subject and using manual focus "pull the shot" so to speak. (btw I have a ND filter on in addition to the onboard ND and the iris opened up as much as possible).

The thing is I cannot "pull focus" on say a head & shoulders frame unless the background is way..... in the distance, then it is pretty easy. I am talking a long way off btw.

Q - is this possible with the XM2/GL2 or is this restricted to the broadcast Cams?

Robin Davies-Rollinson
June 27th, 2004, 01:17 PM
Alan,
Of course you can pull focus with the XM2.
You will either have to get the subject very close to the lens on a wider angle or take them away about six feet and zoom to about midway of the zoom travel.

Robin.

Alan McCormick
June 27th, 2004, 11:18 PM
I "can" pull focus Robin it is just I cannot do it unless I zoom really close that I only get the edge of the object (head or shoulder). I would like to get a subjects head (like an interview) and have the background o.o.f. without it being 100 yards away.

With the wide angle I still have to zoom in "real" close but will try the 6ft ish and mid zoom travel tip (fingers crossed)

I have tried what you have suggested before I posted the original post and will continue to practice, I want to be able to do it in a few seconds "at will" so to speak so loads of hands on practice ahead of me.

Prech Marton
June 29th, 2004, 03:37 AM
A great telephoto optics, ND filter will help.

And for the focus ring.
What about a lanc controller? Focusing without touching the cam itself!
See my:

http://web.axelero.hu/prechj/pics/my-lanc-1.jpg
http://web.axelero.hu/prechj/pics/my-lanc-2.jpg

Marton