Bullet proof Auto focus at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Open DV Discussion
For topics which don't fit into any of the other categories.


Reply
 
Thread Tools Search this Thread
Old November 8th, 2009, 03:17 PM   #1
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Bullet proof Auto focus

So here is an idea I've been having for a while and I want to share it with anyone of interest in the hopes that someone maybe would want to develop it.

Basically the system consists of a unit on the camera hooked up to the motorized follow focus or the lanc plug which sends and recieves ultrasound pulses.

The second part of the system are small tiny "pins" which sole purpose is to listen for the pulses sent from the camera unit and then send pulses back as confirmation.

That exchange of information should be used to measure the distance between the camera and the "pin", which effectively makes the "pin" act as a wireless focus point.

This little piece of tech, would in my mind be a totally reliable focusing system, which can be customized for any kind of situation.

You can have any number of "pins" attached to any number of objects of interest, and with a single push of a button you can switch between the various focus points. Rendering focus pullers obsolete. (sorry guys)

If this already exists then sorry for waisting your time.. I would like a link tho, since I've never seen anything like it.
Nik Skjoth is offline   Reply With Quote
Old November 8th, 2009, 03:23 PM   #2
Inner Circle
 
Join Date: Nov 2006
Location: Tallahassee, FL
Posts: 4,100
There is a similar (but not exactly the same) product called Cinetape and Panavision has another called Panatape. They also work with ultrasonic frequencies. Again, they are not exactly the same as you've described here, but work along the same principles.

And no, they don't render the focus puller obsolete. Because at times, you'll want to rack focus, or do other things with focus. And frankly, depending on the T-Stop and lens length, you may only get one eye in focus and the other out. How would the "pins" work to that level of precision?
__________________
DVX100, PMW-EX1, Canon 550D, FigRig, Dell Octocore, Avid MC4/5, MB Looks, RedCineX, Matrox MX02 mini, GTech RAID, Edirol R-4, Senn. G2 Evo, Countryman, Moles and Lowels.
Perrone Ford is offline   Reply With Quote
Old November 8th, 2009, 03:34 PM   #3
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Hm interesting.. Thanks for the info Perrone. I would be quite surprised if no one had thought about this earlier, so this was expected.. But yes as you say, it dosn't work quite like what I discribed.

You are right.. There will always be extreme instances where auto focus can't get it right. And in those rare situations you can choose to use hands on approach, which is fine. But here I'm talking about an standardized, easy to use, easy to develop system, which is far far superior to any autofocus found on a prosumer camera today. You simply cannot trust it. With this you can.

IF you want to rack focus then you pre program it to do so (or have a dial knob to go from extreme fast to extreme slow).. There is nothing to hinder you from having a slow focus shift between two pins.
Nik Skjoth is offline   Reply With Quote
Old November 8th, 2009, 05:25 PM   #4
Inner Circle
 
Join Date: Feb 2006
Location: Belfast, UK
Posts: 4,121
I suppose such a system would work on relatively simple set ups, less so on shots which the action can't be predicted (extremely common on documentaries) and those shots with over lapping action, which isn't that unusual. You also tend to get hunting with auto focus systems, especially if the measuring system is confused by on camera action - eg hand movements in front of the focus point. Also, actors tend not to be that accurate as to how, when or where they deliver their lines, so programming any focus pulls could be a problem.

The focus puller is also responsible for setting up the camera kit, changing lenses and a pile of other jobs and the actual focus pulling only takes up a small percentage of their time.
Brian Drysdale is offline   Reply With Quote
Old November 8th, 2009, 06:44 PM   #5
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Brian you're kidding right?

A reliable autofocus (ultrasonic waves don't care about hand movements) is especially usefull in unpredictable situations. Since the point of interest IS ALWAYS IN FOCUS! Your talent can run, jump, make flipflops. And all you have to concentrate on is keeping him in the frame, and decide when you wanna jump to the next focus point (with a push of a button)

Im quite surpriced that I even have to defend the idea. Comeon. Is all you see the things it CANNOT do?
They are surelly plenty.. But hey even if I declared pullers obsolete, this is not a competition, this is about giving control to the cameraman, who works on his own.

I see focus pullers obsolete NOT because the system is better, but because it's cheaper, less demanding and can perform just as well in 95% of situations. It's for the indies, and low budget guys. It's for the canon XL's/sony EX'es with adapters, and the red scarleteers, not for the panavisions, arri's and epic's
They can keep doing what they do. I don't have that kind of money.

So in effect this is about the choice between traditional auto focus, traditional manual focus (on camera not AC), Red's new very anticipated touch screen focus (which I personally think is useless without an AC) or this.

I'm not looking for criticism, not even constructive.. I'm not the developer of the system. What I do need, is yay sayers who demand it to exist simply because YOU WILL USE IT if it did..

Peace
Nik Skjoth is offline   Reply With Quote
Old November 8th, 2009, 07:05 PM   #6
Inner Circle
 
Join Date: Nov 2006
Location: Tallahassee, FL
Posts: 4,100
Nik,

Out of curiosity, what do you think it would cost to purchase a system like this with say, 2 pins so you could have two points of focus?
__________________
DVX100, PMW-EX1, Canon 550D, FigRig, Dell Octocore, Avid MC4/5, MB Looks, RedCineX, Matrox MX02 mini, GTech RAID, Edirol R-4, Senn. G2 Evo, Countryman, Moles and Lowels.
Perrone Ford is offline   Reply With Quote
Old November 9th, 2009, 12:10 AM   #7
Inner Circle
 
Join Date: Oct 2001
Location: Honolulu, HI
Posts: 2,053
When focusing is critical, the plane of focus is often shallow.

In that case, the focusing transducer has to also lie in that same plane of focus.

If the point you want in sharp focus is someone's face, then where would the "pin" or transducer be placed?

Also, this sounds like something that would be applicable only in planned productions. For people doing real-life documentaries and sports, it would quickly prove impractical. How do you tell the camera what transcuder it should be looking at?

It's an interesting engineering problem.

Another possibility is employing a very low-powered infrared laser that works in conjunction with the camera. The laser is aimed by the operator's assistant with a special viewfinder, and the camera uses that coded laser to determine distance to the target. That information is used to set focus.

The assistant aims the laser to determine what is to be in critical focus. No need for a transducer. The downside is that a very, very low-powered laser has to be used since there's such a huge risk of eye injuries.
__________________
Dean Sensui
Exec Producer, Hawaii Goes Fishing
Dean Sensui is offline   Reply With Quote
Old November 9th, 2009, 12:55 PM   #8
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Quote:
Originally Posted by Perrone Ford View Post
Nik,

Out of curiosity, what do you think it would cost to purchase a system like this with say, 2 pins so you could have two points of focus?
Interesting question. Infact I have just seen a post on the viewfactor.net forum, where the dev mentioned their interest in building a ultrasonic distance measurement instrument. If they decide to couple it with their existing follow focus system, it should be a pretty affordable addon. Bellow 1000$ would be my bet, for the measuring unit addon. The tech inside the pins would be very simple. Listen for a frequency, and respond. 50 bucks each.
Nik Skjoth is offline   Reply With Quote
Old November 9th, 2009, 01:13 PM   #9
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Quote:
Originally Posted by Dean Sensui View Post
If the point you want in sharp focus is someone's face, then where would the "pin" or transducer be placed?
Perhaps on the shirt collar, in the hair, worst case inside his mouth.
Or... With a focus point system like this, you could IF you wanted to, add a offset modifyer to it. Which would enhance your options for critical focus even more.
And dont forget... The focus ring on the lens is still available to use for ultra shallow focus. Even a puller can't pull a focus if it's depth is a few inches without preparation. Even less so if the talent is moving.

Quote:
Originally Posted by Dean Sensui View Post
Also, this sounds like something that would be applicable only in planned productions. For people doing real-life documentaries and sports, it would quickly prove impractical. How do you tell the camera what transcuder it should be looking at?
The controller unit can have buttons or dial wheel "Focus Point A" "Focus Point B" "Ect. ect." Press and execute. Simple as that. So to use your example for real-life docs and sports.. As long all participants have a pin on them, the cameraman can instantly at any point of time select a focus point to swith to. (just like a focus puller)

Quote:
Originally Posted by Dean Sensui View Post
Another possibility is employing a very low-powered infrared laser that works in conjunction with the camera. The laser is aimed by the operator's assistant with a special viewfinder, and the camera uses that coded laser to determine distance to the target. That information is used to set focus.

The assistant aims the laser to determine what is to be in critical focus. No need for a transducer. The downside is that a very, very low-powered laser has to be used since there's such a huge risk of eye injuries.
So you think it makes more sense to have 5-10 assistants running around pointing laser beams at all the talents in the scene?

Last edited by Nik Skjoth; November 9th, 2009 at 01:48 PM.
Nik Skjoth is offline   Reply With Quote
Old November 9th, 2009, 02:02 PM   #10
Regular Crew
 
Join Date: Jun 2004
Location: Hollywood, CA and Roma, Italia
Posts: 155
Great idea as a focus assist.

Quote:
Originally Posted by Nik Skjoth View Post
Rendering focus pullers obsolete. (sorry guys)
Nik, I don't see focus pullers becoming obsolete anytime soon, and a really good puller gets a lot more work than most DPs.

A lot of directors I work with like to shoot at thin stops, so a good focus puller is critical to the whole mix. This would just be another excellent tool to add to that mix.

This is a great idea as a focus assist, especially with the preset focus points idea, so you should go ahead and develop it.

I use the Panatape unit a lot on my Steadicam rigs (as a visual reference point for the focus puller - helps the puller to stay ahead of my moves), and it works very, very well, so the principal is sound.

You would really need to incorporate it with a wireless follow focus system to really be effective.

Hey, anybody know how the Hocus Focus project is coming along?
__________________
Enzo Giobbé
www.enzogiobbe.com
Enzo Giobbé is offline   Reply With Quote
Old November 9th, 2009, 02:30 PM   #11
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Enzo thanks for your input. I have to say that I agree 100% with what you say.

The statement "rendering focus pullers obsolete" was more a dramatic punchline than a forecast.

I think that this would infact be a very good tool for focus pullers to use (especially those who are inexperienced).

As I mentioned earlier, I read about viewfactor focus systems announcing their distance measuring unit. This made me very happy. And I can only hope that they have vision enough to use it in conjection with their existing follow focus products. Their Wireless remote (Impero) is almost ideal for a focus point controller, where the buttons serve as point selection, and the wheel serves as focus shift speed/focus point offset dial.

Unfortunatelly I don't have the means to develop such a system. All I have is the idea, and the need to own it.
Nik Skjoth is offline   Reply With Quote
Old November 9th, 2009, 07:38 PM   #12
Inner Circle
 
Join Date: Oct 2001
Location: Honolulu, HI
Posts: 2,053
Quote:
Originally Posted by Nik Skjoth View Post
So you think it makes more sense to have 5-10 assistants running around pointing laser beams at all the talents in the scene?
You don't need ten lasers.

The camera can focus only on one thing at a time. Just point the laser designator at the proper target and the camera focuses on that. Point it at another and the camera focuses on that. But the laser idea is just hypothetical. As I mentioned, I don't think it would be a good idea to have IR lasers pointing at people's faces because of the potential risk of eye injuries.

As for putting a "pin" in an actor's mouth... well, it's not very hygenic.

Honestly, in practical terms, anyone who has to focus a camera for a living won't need this kind of gadgetry, and won't want to mess with the complications of plugging in offset values or figuring out where to stick focus targets on talent for every shot. Good cameramen can do a fine job with any camera with any lens. No additional electronics required.

While this is an intriguing engineering problem, it's time-consuming enough to block out shots, sort out camera positions, set up lighting and noiselessly hide lav mics in wardrobe. Having to determine pin positions and hiding them in clothing or hair for every single shot is yet another distraction to actors who already have a lot on their minds.

A skilled cameraman or assistant can get great results with nothing more than a good viewfinder and a responsive focus knob that has zero backlash. Sometimes they do it with just a tape measure and a grease pencil mark.

A prime example of professional focusing is the NFL Films cameramen. Take a look at how they can track a football thrown toward the camera -- from the quarterback all the way to the receiver -- and have it stay in constant focus AND be nicely framed. It all plays back with amazing precision in graceful slow motion, often tack sharp.

With a large monitor attached to a production camera, a focus puller can easily see when something is in or out of focus. I did it as an assistant camera for an independent production here. For my own work I shoot everything with manual focus out on the water in boats that are constantly rolling.

As a news photographer I shot everything from portraits to boxing to hostage situations with nothing but manual focus with a Nikon. Auto focus was introduced during the 24 years I did that and, frankly, I have never trusted it. About the only focusing aid I rely upon now is the "expand" button on the EX1 which gives me a momentary 2x magnification so I can make sure the shot is sharp.
__________________
Dean Sensui
Exec Producer, Hawaii Goes Fishing
Dean Sensui is offline   Reply With Quote
Old November 9th, 2009, 09:17 PM   #13
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
I respect your input Dean. And take notice of that you are not the target customer for this idea (yet).

As you say.. An SKILLED cameraman, can do this - An SKILLED focus puller can do that.
In my book. Skill comes with a high pricetag.

I can see where you are coming from tho. You are a part of the elites in this industry, and don't feel the need for yet another tool, which basically does what you allready have mastered.

Some of us are not as gifted.

Similar opposers were shouting out in the DJ'ing profession, when CD players with beatcounters, auto pitch and tonality matchers were introduced. Suddently everyone could be a DJ with little effort and understanding. But now the elites have found ways to use this new tech to be even sharper, and maintaining their edge. They use the tools when needed, and refrain from using them when it's not needed. The choice is all yours.

It's funny that you should mention NFL, where the television crew is likelly the very essence of tracking rigs. The football has a GPS build in for god's sake.

Of course you don't trust current existing auto focuses. I don't either. That has to change.

As to your laser pointer idea. Reason for having more than one laser pointer, is simply to stay ahead of the action. With only one, you will lose track of your current object (if it's moving) while scouting for the next. (I thought that was obvious).
Yeah don't tell me. If they are skilled enough, they can pull it off - maybe.
Nik Skjoth is offline   Reply With Quote
Old November 9th, 2009, 10:13 PM   #14
Inner Circle
 
Join Date: Oct 2001
Location: Honolulu, HI
Posts: 2,053
Nik...

Please don't think I'm trying to belittle you or your idea. I get what you're trying to do and there's nothing inherently wrong with it.

I'm just saying that if you're going to market a solution, carefully consider how it might fit with a real-life production environment. Otherwise you're going to risk doing a lot of work that might prove fruitless. For example, the money spent on a focus tracker might be better spent on a really sharp, color-accurate field monitor which can serve several purposes (focus, color, exposure, composition, playback) and provide a small production company with a higher return on investment.

I'm hardly among the elite -- I don't consider myself in that class. I'm not infallible as I've had my share of unfocused shots. And guys like me whose aging eyes are now stuck in the "infinity" position can use all the help we can get (presbyopia sucks) :-)

But I've done this a lot and have a good idea of what works on a practical level. In my case it's a viewfinder that provides a crisp image and is adjustable to allow my eyes to see the shot clearly.

But with any keen skill set, the price of entry is practice. Whether it's playing the piano or nailing a focal plane, someone who does something a lot often becomes pretty good at it. After a while you might discover that what you really want, instead of a complex autofocus system, is simply a better viewfinder.
__________________
Dean Sensui
Exec Producer, Hawaii Goes Fishing
Dean Sensui is offline   Reply With Quote
Old November 10th, 2009, 08:22 AM   #15
Regular Crew
 
Join Date: Jul 2007
Location: Cph Denmark
Posts: 136
Good post Dean.

I admit that there are a lot of things in this industry I know very little about.

Ive been told from multiple sourced on a nother thread in this forum: "Building" a focus puller
That focus pullers do not berry their head in a monitor or viewfinder. Instead they rely on measuring tapes, and eyeballing the changing distance as the actor is walking through the scene. So imagine my confusion when you tell me the exact opposite. I guess people use different approached to do the same job.

You are asking for a real-life production enviroment example. So I will give you one:

In this scenario you are the focus puller and you are standing next to the dop (as many do) with no monitor to look at (as many do).
In the scene the dop will follow the entry of an actor coming in behind a door 30 feet away, and walk straight up to the camera untill he's standing right infront of it.
Before the actor takes the scene, you spend 20 seconds placing a pin on the his collar.

After that you do the usual preperations. Measure the distance from the point where he enters the scene, and up to his final position and the camera.

You grab your follow focus remote, which has all the manual functions that you are used to, and ready for action.

The director yells "action"

Camera frames the door for a medium shot. The actor opens the door and walks in.
You follow his walk with the remote by eyeballing his distance to the camera. Scene done.

The director decides that the scene needs more intensity and asks the dop to retake the shot and go very tight on the actors face while he walks towards the camera.
Now you know that you are in trouble.. The tight shot makes the focus so shallow that it gives you an error margin of only 5-7 inches. and its a 30 feet walk.. There is no way you can eyeball that distance with that lvl of presission. NO WAY!

Director yells action. Actor walks in. You focus on him while the shot is still a medium frame, but then the dop goes in for the tight shot.
Your remote is (besides your manual controls) equiped with focus point buttons. As the dop goes in tight you press "focus Point A" which is on the actors collar.
Now.. You know that the shot is very tight.. and the collar is about 3 inches further behind his eye distance. Luckilly your focusing wheel on the remote became an offset dial at the moment you pressed "Focus Point A" so you quickly adjust the wheel to offset -3 inches. >>>Notice that you do that on the fly - in action - no preparation.<<< The focus is dead on his eyes. Director is happy. You dont have to do anything while the actor continues his walk, The focus will continually stay fixed on his eyes in the -3 inches off collar position.
Should he turn his head you can adjust for that by turning the offset wheel accordingly.

Now tell me why this isn't brilliant!

People seem conserned about the whole offsetting issue, when it infact is exactly what focus pullers do, only from a different point of origin (the camera)
Nik Skjoth is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 11:49 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network