Camera Controlled Focus System

I would start with patents and technical papers from companies like Canon and Nikon. They have sophisticated algorithms for doing just that with out the external beacons etc.

What you are suggesting is very primitive compared to what modern cameras and video cameras have now and they work extraordinarily well.

http://www.google.co.uk/search?q=polaroid+focusing+system&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=U-iOTLKxHNS7jAeGmcmMDQ

http://www.google.co.uk/search?q=auto+focus&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=keiOTM33NsK4jAeDnZD_DA

Hmm. If I understand correctly these two responses refer to still camera autofocus features. I shouldve been more specific as to why These won't work. The lag time it takes for the system to find it's subject and calculate distance from it causes Long moments out of focus. with film the subject must always be in focus and as the camera moves to and away from the subject the operator must adjust. The shot I am considering must be done without an operator. Hence the question is more weather this beacon/sensor device exists. That's for te quick replies and sorry for the lack of specificity.

most existing auto focus system will keep the object in focus as the object moves towards and away from the camera

the other way of ensuring a greater focus depth is to use as small an aperture as poss the smaller the aperture the greater the focal depth

if poss please explain the use of the camera for the desired result.

ie surveilence ?

http://www.google.co.uk/search?q=depth+of+field+photography&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=b_OOTK2VNNC6jAefseHhDA

"ie surveilence ?"

Now that would make a great fiction story! ;-)

The rain had just stopped, but the stench of the humidity was everywhere. The burglar crept along the wall and finally reached the doorway half soaked. Upon entering he found a curious sign with a plexiglass container standing next to the inside door:

"Please Affix this Badge to your Left Breast Pocket Before Entering. Thanks for Your Cooperation - The Management."

"The lag time it takes for the system to find it's subject and calculate distance from it causes Long moments out of focus."

You must be living in the mid 19th century or only have seen cheap equipment. I have an 8 year old Nikon that focuses in milliseconds. In fact, Nikon has had systems that focus very quickly for decades. These are not pocket cameras or cell phone cameras, but higher end amateur and pro gear.

The lag time is due to the mechanics of focusing the lens, not the microprocessor determining where the focus should be. The micro works in a few milliseconds, but turning the gears in the lens is what is the bottle neck.

What you are proposing is totally unnecessary and I know of no such system. Modern focusing systems are extremely quick (limited only by the mechanics) and have powerful algorithms. The latest crop of cameras now can discriminate the subject's nearest eye in the field of view and focus just on that point. Other algorithms compute the closest subject, others use highly sophisticated means to pick subjects in motion or in very low light.

If you think about it, how have photographers been able to capture all those amazing sports photos and videos? They don't rely on manual focus techniques, but utilize sophisticated software and motors built into their camera to achieve the results you take for granted.

Again, the real issue is getting the lens to mechanically focus as quickly as you need it. To do that usually requires expensive lenses. My 70 - 200 mm zoom costs about $1800, but not only is it extremely sharp, its focus speed is designed for action sports and therefore very fast.

Hi all. Thanks again for the replies. I am a filmmaker and am aware of the lenses mentioned and shooting techniques, I ought to have gotten into the specifics a bit futrther still, all apologies. To be more specific I actually need a shallow depth of focus. This makes for a more subjective feel for the film, so while deep focus would make it easier to maintain a subect it doesn't make them pop out of the background the way I need for the aesthetic of the film. The other problem with autofocus which makes it distinct from the system I describe is it's not smart focus, in the sense that if I am moving camera past, say, a series of pillars in a parking lot, but hope to keep my subject, who is weaving in and out of cars past those pillars, in focus, auto focus would continuously rack focus between her and the pillars racking between them, possibly racking to vehicles etc. The system Ive described would instead use it's distance from the beacon as it's only information for focus. I realize it is more primitive, in most situations, like the fast paced sports game described, it would be totally useless, but in this scenario it is truly better than autofocus. Please take my word for it I have used lenses with autofocus. Any ideas as to how such a beacon/sensor might be developed?

well surely you would just set the depth of focuse to include the object say in a 4 foot depth of field view then when panning say right across line of pillars the person and the pillars would be in perfect focus so long as both items where in the focus area, the background and fore ground would then be out of focus.

the other way would be to program the iris to change

ie moving shot to right target starts 8 feet moves to 6 feet then back to 8 feet and so on so focus moves in and out at a preset speed as camera i moved left to right, then so long as the tatget moves back and forth and to the right at the same speed as the camera all is well.

It should be possible to build one of those easily.

or can you not program cinema type cameras to do this ?

another way if that doesnt work is to use the fixed focal lenth and thus fixed depth of field, and using somthing like photo shop blur the background as required to give the illusion of zooming in and out.

For that kind of choreographed work I would consider a custom algorithm that would dynamically maintain a preset focus point throughout a specific section of shoot. That would require the subject to carefully follow a preset course through the scene.

A second variant would be to use a tracking system for the subject and the camera. Systems exist that uses lasers to pinpoint people or objects within a space or theater. I have seen such systems at I/ITSEC in Orlando and they are used for training, but the principle can apply for your needs. The system can read the positions of people and their limbs that it was used to create a video representation of the subject as they moved about. Essentially, the system created a 3-D virtual model of the theater in real-time.

Since both the subject and the camera are dynamic, the tracking system simply needs to feed the XYZ coordinates of the subject and the camera to a computer that controls the lens focus system based on simple geometry calculations. A small microcontroller can do that part. You can choose what point of the subject you want to focus on.

I really don't have experience with laser scanning and positioning, but the technology is pretty mature. Applying it to your problem set should not be too difficult.

It would seem that the film industry would have already crossed this bridge. Have you researched prior art out there that may have already solved this problem?

As i thought there are computer controlled focus pullers

did a google for you

http://www.google.co.uk/search?q=computer+controlled+focus+pulling+on+cameras&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=dIePTL_qFYuRjAf-_tiFDQ

http://www.dvinfo.net/forum/open-dv-discussion/21896-any-ideas-homemade-focus-puller.html

if you have any problems let me know i am sure i can make a crude version, it wouldnt be computer controlled though

Several Years ago I worked with Dan Diaconu on his patented focussing system http://polisoftdesign.com/portfolio/servo-motion-controller/ This system is unique in that it will allow you to keep focus on the object (or even a void - like an open door frame) without fail.

It looks like you are asking for a distance measurement system more than the focusing aspect. I do not know about the technology available today for autofocus, but it looks like you have that handled.

I have a radar background. It seems photo work is done with acoustics or light. Sound has lower resolution and has probably been pushed to its limits. Light might interfere with your pictures. Thus radio waves could work. But it would be very expensive for a custom solution with off the shelf parts. So I do not know about the cost effectiveness of such a device.

I am working on in home radar monitoring of distance and heartbeats. The cost is very large compared to hiring someone to be there and adjust existing equipment capabilities.

The question is how interested, in "willing to invest" terms.

Given the variety of emissions on a film set and masking of the camera or talent, in reveals etc, most optical solutions are out. So you are looking at a highly encoded 'radio system' (subject to all sorts of frequency allocation and approvals).

However, you are also obviously seeking remote operation, and having done some system concept design in a similar fields, it seems to me, you want a position for the camera lens and a position for the target, rather than a camera or target based infrastructure approach.

"In principal" like GPS, where you can track both and compute the distance. A bit like giving them both an iphone but having mil-spec resolution.

Not as "big bucks" as that total infrastructure, but well big enough to test most people's wallet's 'commitment'.

Hence Q1

Just a dumb, non-cinematographer thought...

Green screen and add the background with a soft focus?

Just tell me to go away if you like.

Hooker

His conversation is really heating up and getting exciting. Yes I thinkthe previous posted is right, I am talking about a distance calculating system focus pulling is secondary to it. Unfortunately green screens, Photoshop (or I would actually use after effects the filmic Photoshop) and subject coreogaphy are both out (though awesome brainstorms). As is budget for that matter, so it sounds like radio waves are out. , I wonder what the real issue with light would be... Would a beam from the lens' distance need to fire into a receptor on the subject? Or vice verse? I actually may be able to work around extra light, but if other lights needed to illuminate the scene would interfere that would be a problem. It would also be preferable to not see the sensor or be able to use production design techniques to mask it (assuming it is not so bulky). What do you all think of that? Thank you for your consistent interest and focus, I'm very excited to hear back!!! Rr

I'm a little confused by your post and apparently movable goal posts.

If you just want the lens to subject distance and are now not worried by masking prior to a reveal, then use/modify, a laser measure.

(click on shot for link)

"development" required is to output the display value to a remote receiver. Can be cable or WiFi or IR.

If you don't want to fix the tiny visible spot in post, or show in fog/smoke, then get someone set it up as IR.

An IR spot will show on B&W CCD, (but not in B&W or color film, or color CCD)