Autofocus

[damonbots]

Yeah, I know... "real cinema cameras don't have autofocus and they never will".

Can you imagine if Jim said "an inexpensive 4K camera doesn't exist and it never will"?

I just hate the word "never" and I especially dislike close-mindedness.
I'm just wondering if the RED team would ever be receptive to the idea of implementing some sort of autofocus on the RED ONE in the future. The RED camera is based on revolutionary ideas. Why stop now? I bet Graeme could design one hell of a focus tracking algorithm.

[Michael Mann]

The RED camera is based on revolutionary ideas. Why stop now? I bet Graeme could design one hell of a focus tracking algorithm.

I absolutely agree! There is no reason at all why an (optional!) intelligent AF should not be part of a professional camera.

[Stuart English]

O.K I'm game to continue this discussion - focus on what?

[PaulClements]

Ok Stuart for a bit of fun, here goes. Mind you I don't have a clue about this stuff so take it with a pinch of salt if you will (Before you tear it apart) :)

What you would need:

• Motorized follow focus or lens that can be controlled by the camera
• Device for accurately obtaining the distance of objects away from the camera (If not available through an intelligent lens or via the sensor).
• Software to detect the sharpness of and around objects and distinguish patterns in colour and shapes (Magic Focus?)
• Database of lens settings

Step 1: Sync the lens/ff for the scene
Step 2: Choose an object or person to maintain focus with (Physically point using a cross hair perhaps)
Step 3: Set the auto refocus time (If an object moves in front of the object you are focusing on how long before the camera should refocus, if at all).

AND BEGIN SHOOTING

As the object, person or camera moves, the center of the sharpness of and around that object maintains the area on the sensor that requires focusing, it captures the distance that object is away from the camera. As the object moves toward or away from the camera it takes the distance and recalculates the focus according to the lens settings and distance for the person or object.

N.B. If an object should move infront of the lens and then move away and the object previously being focussed on has moved to a different focal point the software detecting sharpness would have to be intelligent enough to guess the most likely source for refocussing on by using the colour, shapes, relative distance and sharpness to make an informed guess.

[damonbots]

O.K I'm game to continue this discussion - focus on what?

Well, I'm hoping to focus on an icy cold Newcastle when I get off work, but
in regards to my original comment, I guess I'm thinking about something similar to the AI servo AF mode on my DSLR. I imagine this would complicate things significantly, but I'm sure quite a few folks could justify the added expense, especially if the feature was as revolutionary as the camera is now.

Edit: Paul, that's exactly what I was thinking. Nice!

[Martin Drew]

Okay. I can see a place for auto focus, firstly as an off shot tool for helping to mark focus positions. In theory this could be more accurate than a tape measure because focusing would be part of a feedback loop, especially valid if using stills lenses for example. Secondly for very tricky tracking shots eg keeping focus on someone as they run towards the camera, while maintaining minimal DOF.

You would require a means to input the focus target, this could be a separate device operated by a focus puller, maybe a touch sensitive screen or a position sensing controller that could be moved about.

I never have a problem positioning my stills camera in order to define a focus target so maybe there could be a target definition interface which works in a similar way for the camera operator to use, for example a collar on the viewfinder which can be moved by your left hand. Your hand would rest against your cheek, in the same way it might if you were holding a telescope. small positional movements of that hand would move the collar and there would be a positional relationship between the collar and an onscreen focus target. To define the target you would press a button on the collar with your thumb. The camera would only autofocus while the thumb button was pressed. Don't know how practical this would be ergonomically, just thinking out loud.

M

[Clayton Harper]

If the camera assistant could paint the target/subject with a "pointer" and have that info fed into the red focus motor, that would be insanely great.

OR, in the VF there could be focus areas like the ones you see in your digital SLR auto focus and you could somehow use those to target the focus. Martin is onto something there.

[miskamagic]

If such a thing does not already exist, what I always thought would be cool would be to have a 'key' that you attach to talent or an object, like a small clip that contains a tranceiver. Wherever that key went, the autofocus system would keep focus on it. It would have to be radio activated, not line of sight like lasers or IR, and I have no idea how the math/geometry would work since of course its not a simple thing of perpendicular distance to the lens. If the keyed object is off to one side of the lens, its now at a diagonal from the sensing device and its absolute distance from the lens is different from distance to its plane of focus.

Of course this wouldn't be useful in all focus pulling situations, but it would make certain shots much easier if not possible in the first place. Also you could do a lot of cool special shots, like imagine putting the key in a soccer ball and then kicking it around, everywhere it goes it stays in focus, yet swimming in a blurred environment around it.

You could also expand the system to use multiple keys and have some facility to tell the system to 'rack focus from key A to key B using X amount of speed doing it', use exponentinal vs linear fades from one focus point to another, etc.

-miska

[LighthouseMEdia]

Okay interesting point guys but a few questions.
1. so you want a laser on your subject?
2. what about when their torso where the transmitter or laser is hitting
is in one place and they lean in 6 inches on DOF shot of just inches and you want only their eyes sharp?

Don't get me wrong, I think it is a great idea just not sure on the practicality of it.

[zoltan77]

I was thinking of something incredibly small, like RFID sensors (no idea if the technology would actually allow you to do something like this though).

RFID is something like the size of a head of a pin. Imagine you peel off a disposaple sensor, type/scan its unique bar code into the autofocus system, conceal sensor under makeup on the other side of talent's nose, in an eyebrow, etc. wherever you desire exact plane of focus to be. When you're done with the shot, throw away the sensor, repeat for another shot.

-miska