Talking About Cinematography

Recently I found myself writing papers, notes and drawing sketches about Cinematography stuff for my class, along with answering question as: 

"Describe the operation of digital video camera systems."

First of all, before focusing on the work-flow of a Digital Camera shooting process, we need to briefly discern between concepts of Analog and Digital movie cameras since both types are nowadays used to shoot a Movie Picture. Talking clearly and concisely, we can state that Analog Camera mechanism impress images on film support, while Digital Camera technology capture light through a sensor and processes this information into data that can be stored in many different ways. Basically Film is a chemical process while Digital is more like a combination of electrical impulses.  So a Digital Video Camera System is essentially composed by a lens rig, a sensor for capturing the light, a processor for scanning and translating the analog image into digital data and eventually a recorder for storing this data on a support like a memory storage device. It is as well possible to directly project this image source instead of storing the data on memory.

Basically the main functions performed by the Film in the classical Film Picture Camera, is similarly achieved by the combination of sensor+processor+memory storage. The light passes through the optic lens, which could be either consumer or professional quality lens depending on the Camera model, and hits the sensor. This device, which dimension is related to the quality of the final image precessed, was first created in the late 70’ and called CCD (it is used a CMOS sensor, similar device). The Charged Couple Device reacts the light giving back an electrical impulse carrying luminance and light color values. The sensor is made up of a modules grid and each module, which design could be single or triple layout, analyze a little portion of the incoming Analog image that represent a pixel in the final Digital image. A single layout sensor has a chip that analyze both Luminance and Color of light. A Triple layout sensor is provided with a beam splitter prism which separate light beam in three main chroma values, and three chips for recording each color component as Red, Green and Blue.

During this capture process the image is scanned that is every pixel is reconstructed digitally according to an Interlaced or Progressive scanning system. The difference between this two systems lays in how you get the final frame: Interlaced (i) method scans every odd pixel line from top to bottom of the frame and then all even pixel lines, obtaining two fields which together make one entire single frame. Progressive (p) scanning directly analyze every pixel line of the frame from top to bottom. During this Analog-to-Digital conversion, the data can be compressed getting rid of the wasteful information to avoid large file size. The final file video can be processed into different stream standard (combination of different formats and different frame rates) such as PAL (720x576, 50i), NTSC (720x480, 60i) and HD (1920x1080, 25p or 30p) according to the standard quality of the Digital Camera used or the compression type.  Eventually the data streaming is recorded into a memory storage device.

These are basically the principal steps that make up a Digital Video Camera shooting process.

"Describe the action of the Intermittent Movement mechanism of a film camera."

A Film Camera is a complex machinery for capturing moving images and “printing” them on a film reel. So in order to correctly scroll this roll and get every frame properly impressed in the right moment, a sophisticated mechanism drag the film in front of the gate where light can strike it and print the image. 

This mechanism allows the unexposed film to travel from the roll magazine to the film gate through a claw that grabs the lateral rail holes of film. In the film gate area the register pin holds firmly the film straight to the aperture where light from the lens pass through. The exposed portion of film, the new image frame, is impressed when the 180° shutter allow the light to get through by constant rotation. In the exact moment when the 180° shutter stops the light beam, the exposed film runs into the safe storage magazine while the unexposed portion of film moves up at the aperture in order to be stroke by light and repeat the cycle. This process, called Intermittent Movement, takes place 24 times per second or even more if we are using a high speed camera. 

The Film Camera is a very delicate and sensitive machinery, so it’s important to handle it properly in order to avoid grave damages.

"Describe the essential Spherical and Anamorphic imaging systems and advantages and disadvantages of each."

Focusing on the shape of both the lens and the frame we notice that the lens is round while the frame is a rectangle. So the real portion of image the lens can capture is round, but the area of film that will indeed be exposed to light is a small rectangle whit defined proportion that can actually fit in the lens round. In Normal spherical imaging system photography there is a portion of film which is dedicated to sound that reduces basically the real image frame that can be exposed. It is possible to exploit the sound area for gaining more film as happens using Super 35mm spherical system. In both cases, spherical imaging has a significant waste in terms of actual image coming from the lens, but can provide a clean elegant frame which aspect ratio is related to reality and maintains proportions of the real image. 

The aspect ratio values from a Normal system can vary from 1.33:1 - 1.66:1 - 1.85:1 and up to 2.40:1 using Super 35mm system. Otherwise the Anamorphic imaging system allow to horizontally squeeze the real image through an additional lens, obtaining a different exposition area on the film frame. This kind of operation is definitely more efficient in terms of negative film usage and allows to rake in the effective image exposed area as well (up to 60% more film area), but involves two more passages in order to squeeze the incoming image and, once the negative film is printed, unsqueeze the image back for projecting the movie with correct original proportions. Is interesting to notice that, during this process, some of the lights artifacts printed on film, such as lens flares and light spheres, undergo the anamorphic effects changing their shape and proportion.

"Discuss the concept of Depth of Field, its technical meaning and how it's used in creative ways."

Every type of lens you can use to shot can actually achieve one single precise focus point in the image at one distance, that is where the image looks sharp and clear with no blur or fuzziness. This particular point is placed at a certain distance from the lens called Focus Distance. From that point forward in the space and backward to the camera the image will gradually loose focus to became indistinguishable. The decrease in sharpness is gradual on each side of the focused distance so that in normal viewing conditions the portion of the blurred image is imperceptible. So related to film photography,the distance between the farthest and nearest objects in a scene that appear acceptably sharp in the final frame image is called Depth of Field. A large DoF is a Deep Focus while a small DoF is a Shallow Focus.  

Depth of Field Value is affected from many factors and lens characteristics like Focal Length, that is the actual distance from film plane to the optical center and basically defines the type of image lens can achieve (18-28mm “wide-angle lens”, around 50mm “normal lens”, from 85mm and up “long lens”) so that using Wide-Angle lenses, objects are pulled in space from the side and pushed away from camera, while using Long lenses objects are pulled closer to the camera like in compression of space. 

Another important Optic value is the Aperture Stop, namely the opening dimension that determines the amount of light allowed through the lens: a narrow aperture (like 8 or more) involves a sharp focus at the image plane, conversely a wide aperture (2 or 1.4) results in an image that is sharp around what the lens is focusing on and blurred otherwise.

The relation between lens’ focal length to aperture stop diameter is called f-number (f-stop) and affects the overall composition of the image frame, from what objects of the space are actually included in the frame and in which perspective, to the sharp or blurred portion of space we want to achieve. For example in a scene where both objects at infinity distance and object near the camera are in focus, we get a Hyperfocal Distance setting.

Playing with Optical values being aware of the effects we can achieve, is a powerful weapon to greatly enrich the narration through images. DoF can be used to emphasize particulars, hide in an elegant way unnecessary portion of the image or even lead the public to capture nuances of the story creating unique atmosphere and giving a defined style to the all movie picture as well.

We can define The Cinematography both a work of Art and Craft. The Cinematographer must use his creativity and apply his personal and unique view in lighting a scene, working as an artist and achieving something basically unrepeatable. On the other hand a Cinematographer is a figure hired with commercial purpose, that has to grant a sort well defined standard product as well. According to these statements, it is clear how difficult becomes to achieve both goals in being a good Cinematographer. Probably to be able to judge where one feature is more important than the other could help to maintain flexibility in job being both creative and standardized.

Copyright and Drawings by Pietro Torrisi, nov. 2012, Los Angeles, CA