follow focus

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i know this is pretty random but im kind of new to high end filmmaking and interesting the dvx100 which i am going to get soon hopefully. i've been seeing the words "follow focus" a lot of places. what is a follow focus mechanism?
 
Re: follow focus

A follow focus mechanism is a geared wheel that attaches to your lens.
It’s main purpose is to allow the camera assistant to change (i.e. follow) the focus with greater ease. There usually is a white disc around the “wheel” for noting pre-measured distance marks.

On larger sets, especially when shooting film, the camera operator has an assistant, in the U.S. we call this person the 1st A.C. . One of the duties of the 1st A.C. (in Europe the title is focus puller) is to keep the picture in focus. This is done by measuring the distance from the camera to the actor then adjusting the focus based on the markings on the lens (note: this is, traditionally, not done by eye). If the actor needs to move towards (or away from) the camera the A.C. takes a second measurement and makes a second note on the disc. Now, when the actor walks from point A to point B the A.C. follows focus by turning the wheel from the first mark to the second.

Here is an example of a follow focus on a broadcast style lens
http://www.saferseas.com/vsd/eye/ff.html
 
Re: follow focus

CamOp, excellent post!
In addition to what you just said, a follow focus is (same as a mattebox) one of the cool toys to make your DVX look even more pro and sexy.
It has a price though: Follow focus units are notoriously expensive, there is one from Chrosziel that is around 1.000 USD...
 
Re: follow focus

Follow Focus is something that some comapny needs to design for the DVX100 in OUR Price Range. Damn it.
 
Re: follow focus

That's so true...most of us buy the DVX because we can afford to spend 4 grand on a camera, and *don't* really have many capabilities to go higher up (HD or 35).

$1,000 is pretty steep for my blood, I know, and I bet it's too much for most DVXusers. We'd rather scrounge that cash towards, well, pretty much anything else :P
 
Re: follow focus

My Cavision follow focus just arrived today.

Unfortunately, the gear ring that fits around the DVX focus ring is too small and Jason is not there today. So, tomorrow a call will be in order to get to the bottom of that issue.

Other than that, it is made of machined aluminum, has really nice action in the mechanism, and sits on black carbon fiber rods.

It is a sweet li'l unit with a big price tag - (FF, plate & rails, shipping $950)

BTW, a Chrosziel FF *starts* at about $1,300... then add baseplate, rods, etc. A Chrosziel system for DVX will cost you at least $2,000.
 
Re: follow focus

[quote author=Mike_Donis link=board=news;num=1086103351;start=0#4 date=06/01/04 at 10:17:33]We'd rather scrounge that cash towards, well, pretty much anything else :P[/quote]

I agree.  A follow-focus is very, very handy in 35mm, but I've never bothered with it in 16mm, and certainly not on the DVX.  With the DVX it's hard to design a camera move where you need to track focus at all... with 35mm, you're frequently working with depth of field that's maybe three or four inches, whereas with the DVX it's rarely less than three or four feet.

Don't get me wrong, I'd love to have a proper FF unit for the DVX, but I wouldn't pay $1000 for it...  There are too many other accessories to get, that will provide more real-world benefit. I'm not saying a properly-engineered unit isn't worth $1000, just not worth a grand to me.

I'm sure someone could design one in CAD that we could get manufactured in bulk for $50 apiece... it doesn't need to ride on rods, it doesn't need to have a spring-loaded gear or interchangeable gears with industry-standard tooth pitch... all that stuff is designed into professional FF's because they have to be able to accomodate different lenses, different lens barrel widths, different placement of focus rings, etc.  The DVX doesn't need any of that -- it has a fixed lens, fer cryin' out loud!  ;)  We just need something that has a gear wheel that interfaces with the DVX's focus ring, clamps on to the lens barrel, and offers a remote turning surface.  Let's get someone to design that in AutoCad and then give the plans to Jarred, he'll use his contacts overseas to get it manufactured, and we'll have $50 follow-focus units for everyone!
 
Re: follow focus

This has been mentioned before several months ago.

No CNCers or CADers volunteered anything so I went ahead with my purchase.

Some of you may have read my post concerning using the DVX to shoot commercials. In that post, I mentioned how some producers are snobs about the cameras they use.

Sometimes producers just refuse to yield to a 'small' camera because they are afraid their client (who may be video illiterate) will balk at the sight of such a small camera when they are paying big $$ for the shoot.

To this end, I have decided to step up the "PRO" look of my DVX by outfitting it with a 4x4 mattebox and, now, a follow focus unit.

Not that I'll need it for every shoot, but if nothing else it will serve as a placebo for those who equate bigger camera with better quality.

Of course, I'll reap the actual image and operational benefits of each in addition.
 
Re: follow focus

Excellent point -- if the addition of the tools gains you just one or two days' additional work, they will have paid for themselves. In that case, they are well worth the cost!
 
Re: follow focus

[quote author=michael_summers link=board=news;num=1086103351;start=0#9 date=06/01/04 at 16:18:40]thanks a lot camop. [/quote]

You are welcome! ;D
 
Re: follow focus

OMG Barry is sooooooooo right. Please lets find someone who can desogn a Follow Focus for our DVX. I'd pay for the time! Please!?!?
 
Re: follow focus

[quote author=Barry_Green link=board=news;num=1086103351;start=0#6 date=06/01/04 at 10:48:10]

 Let's get someone to design that in AutoCad and then give the plans to Jarred, he'll use his contacts overseas to get it manufactured, and we'll have $50 follow-focus units for everyone![/quote]

A few months ago I started the process... found a company that would make the bevel gear box the right ratio, a beveled gear that would accept the dvx ring, a nice 2" knurled knob and a small mount plate that would interface to the bottom of the camera.. but all in all out of 7000 series aluminum it still was still too expensive (about $300) unless I bought 10,000 of them.

I think we need to find a DVXuser member like Roger (what ever happened to him?) who has a machine shop and doesnt charge $5,000 for a prototype :)
 
Re: follow focus

[quote author=Jarred Land link=board=news;num=1086103351;start=0#13 date=06/01/04 at 23:43:39]A few months ago I started the process... [/quote]

Did you have any plans drawn up? Or, any details of the dimensions for the various parts? The gear ratios were something that I've also been interested in. Not sure what would provide the best feel.

I have Autocad, 3D Studio Max, and various other design apps. I've started measuring my camera so I can create a simple 3D model that I would then be able to prototype with.
 
Re: follow focus

4:1 seemed right to me.. but it all depends on the size of your focus knob, the size of the drive gear etc.
 
Re: follow focus

I won't comment on Kai's knob, but I will finish the follow focus design I started a while back, to go with our gear for the DVX. And it will have a big knob.
P.S. See our Open House notice in the News section.
 
Re: follow focus

How about a gear ring that works with the Cavision follow focus?

How long do you expect before the FF unit you are designing is available?
 
Re: follow focus

Our follow focus gear is a .8 Mod gear, which is very close to the old film standard of 32 DP. I do not know what Cavision uses (they don't call me very much). Our gear will soon be available with a macro lockout that works with the 100 and 100A (which has a closer focusing lens, before Macro range).
Cheers
 
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