CMOS = Partial Exposure with RED?

[Javier Hernandez]

Having had some bad experiences with CMOS cameras, I just read a very assuring post by Steve Harryman about RED not having any wooble issues.

My other concern is Partial Exposure, is the RED prone to this?

I particulary had problems with audience camera flashes in live concert situations using Sony cameras. Have anyone use the RED in this scenario?

 

[Uli Plank]

Yes, the RED has the same issues like any CMOs camera – if you try to find them.
Wobble or skew has never really been a practical problem for us, but then we don't use 3D tracking. The effect is considerably less than on Sony's CMOS models, but if you desperately need to avoid it, get Sony's F35 …

Partial exposure can happen with flashes.

 

[Paul Leeming]

What nomad said. But remember it's not only Red that suffers from rolling shutter and partial flash exposure - film is not immune. Here's an example someone else posted from the movie "Pitch Black", shot on 35mm film:

Red will display a similar effect. The next generation (Epic/Scarlet) will have faster read/reset times to minimise this and Monstro should be fully adjustable.

The solution if you cannot have this in the footage is to shoot one of the global shutter cameras out there. The right tool for the right job, as always

HTH

Paul

 

[Uli Plank]

Yes, film has this too! An ARRI for example is using a rotating shutter and it's opening can be adjusted for shorter exposure times. But if it's not synced with flashes in the scene, you get partial exposure as well.

 

[Sanjin Jukic]

One more example with RED CMOS and electronic shutter issue

Shot on RED1 with Canon 50mm FD L f/1.2 @ wide open f/1.2.

 

[Javier Hernandez]

"The right tool for the right job, as always "

ah Paul, I would not have said it better!

now, If only the clients understood....

Thanks all for the feedback, will keep my global cam for my guerrilla shootings for now.

 

[JD Holloway]

Turn off shutter in some situations with some cams.
Just don't pan around too much and watch out for moving objects.
Bad motion blur. Gain a stop or so though!

 

[Douglas Underdahl]

Any event that is significantly near the exposure time of each frame will show exposure time artifacts. For example, a strobe light or still camera flash may be recorded on a frame in your movie, or it may not, or you may see part of it, if it is shorter than about 1/48th of a second, which is the usual length of exposure of most motion picture frames. With this length of exposure, half the time, the sensor or film is not recording an image. So if you flash a still camera during this time of non-recording, the flash may not be recorded. Or part of that flash or event may be recorded. Still flashes usually last about 1/3000 of a second. This is also true for muzzle flashes from firearms, liquid splats and splatters, tear drops, and other short lived events. Some flash units or strobe lights used for motion picture work can be synchronized or slaved to the movie camera (guns too) so that they only fire when the shutter is open.

The rolling shuttter of RED poses no more trouble than the wiping shutter of Arri or Panavision, and when you fire still flashes with either camera unless you synchronize, you will have random effects ranging from a full flash frame to a partial flash frame, to no flash recorded at all. In the partials, on RED, you see a horizontal line indicating the way the electronic sample occurs. On film cameras with rotating mirror shutters, you see a slant through the frame, the angle depending on whether the shutter is bottom mounted as in Panavison, Aaton, and some Arri, or side mounted as in the Arri 2C or III.

Some strobe lighting units have the ability to be slaved to the cam via the Fischer or Lemo connector that puts out the signal for such purpose.

Often the best way to simulate a convincing flash is to simply isolate the chosen frame in post and crank up the exposure/brightness of that particular frame, and add the appropriate whirr or snap on the soundtrack.

My old company MEDIA LOGIC made three decimal crystal speed controls that would control Arri, Aaton, Panavision, and Fries conversion Mitchell cameras so that you could shoot video monitors, but our control didn't include a slave. Cinematography Electronics made a pick up device for CRT monitors that would slave the camera to the speed of the CRT, as I remember.

Here's something weird to think about: with film cameras with rotating mirror shutters, neither the camera operator or the video village ever really sees the movie that is being photographed. The mirror shutter only sends an image to the eyepiece or video assist when the film is not recording a frame, but between those frames. This is just the opposite with RED. And you get that spectacular on set HD playback with RED - no surprises.