Cinematografia digital

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  • Publicado : 11 de mayo de 2010
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A lot of you who read this site make movies. Some are big and some are small. I make small movies, and I’ve found in my short time as a Los Angeles filmmaker that you can get a long way with the right equipment and a little bit of resourcefulness. I tend to use the kind of gear that’s accessible to folks without a running tab at Panavision or ARRI. To put it simply, I have a running tab at AceHardware. This is CHUDindie – a column for the independent filmmakers who frequent CHUD.
 
So you want to make your movie more "cinematic." In the first CHUDindie, I mentioned that there are a few variables you can manipulate within your image to achieve a more-filmic quality. This week I'm going to go a bit more in-depth on the topic of digital cinematography.

(Photo at right is of Lars VonTrier and a Sony F900 rig from Dogville. I'm loving the shit out of this.)
 
First let's take a general look at a few of the things that make film look like film (assuming image resolution is a foregone conclusion):
 
24 frames per second
A shallow depth of field
Wide dynamic range

And then there's video (non-progressive):
 
30 (NTSC) frames per second (60 interlaced fields)
Deep focusNarrow dynamic range

FRAMERATE
 
Film is shot at 24 frames per second, an effect that's created by a spinning shutter inside the film camera. The shutter is essentially a circle with  180-degree opening that lets light in at it spins, meaning that in order to create 24 separate frames in one second the shutter is open for 1/48 of a second. Video is shot at either 30 frames per second (60interlaced fields) for an effective shutter of 1/60.
 
The progressive scan format – the "p" in 24p – allows a the lines of a given frame of video to be drawn in a single sequence, as opposed to the combining of two interlaced fields to create a single image in a standard video signal. Shooting video at 24p feels more like film because you're looking at 24 complete images per second.*
 
With bothfilm and video the filmmaker can use the shutter to create a more visceral visual experience. Closing the shutter to 1/120th of a second (at 30fps) or 1/96 of a second (at 24fps) will decrease motion blur and create a staccato effect seen in films like Gladiator and Saving Private Ryan and TV shows like The Shield.
 
DEPTH OF FIELD

Maintaining a controllable depth of field is key when you'redrawing attention to specific areas or subjects within a frame, and your depth of field is greatly influenced by the kind of glass you're putting in front of the camera. One of the things that's characteristic of 35mm motion picture lenses is a narrower depth of field, primarily due to the size of the lens and the image plane.** On your smaller, 1/3-inch or 2/3-inch chip/sensor video camera you'llhave a much wider depth of field, which make the 35mm lens adapters out there right now - Red Rock Micro, PS-Technik, or Brevis35 – popular choices for indie filmmakers looking to achieve that 35mm DOF.

[pic]
 The Redrock Micro M2

In most cases the adapters are configured in front of the stock lens and allow the filmmaker to take advantage of both 35mm cine lenses (PL mount) or 35mm stillcamera lenses (Nikon, Cannon, Minolta, etc). The result is a shallower depth of field and a more "cinematic" image.
 
While effective, the adapters do have some drawbacks:
 
- Longer set up times.
- Light loss (requires more lighting).
- Adds more weight to the camera.
- Extra costs not directly related to the adapter (i.e. camera support to cope with the added weight and extended camerabody).
 
Other ways to knock down your depth of field:
 
- Your f-stop greatly effects DOF. Shooting wide open (at f2.8 or so) decreases your DOF. Conversely, shooting at an f11 or f16 will increase it. If you want to open up your iris but you have too much light then close your shutter or use ND filters to cut it down.
 
There are drawbacks to this method. Lenses have a "sweet spot" – an...
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