1.2 Sensor sizes and formats

Sensor sizes and formats play a crucial role in digital cinematography. They impact image quality, field of view, and lens selection, influencing the overall look and feel of a film. Understanding these factors is essential for making informed decisions about camera setup and creative choices.

From full frame to micro four thirds, each sensor size offers unique advantages and trade-offs. Cinematographers must consider how sensor size affects depth of field, low light performance, and aspect ratios to achieve their desired visual style and storytelling goals.

Sensor size categories

• Sensor size is a crucial factor in digital cinematography, impacting image quality, field of view, and lens selection
• Different sensor sizes are suited for various shooting scenarios and creative goals
• Understanding the characteristics and trade-offs of each sensor size category is essential for making informed decisions in camera selection and setup

Full frame sensors

• Largest common sensor size, equivalent to 35mm film (36mm x 24mm)
• Provides the shallowest depth of field and widest field of view for a given lens focal length
• Excels in low light performance due to larger pixel size and increased light gathering capability
• Full frame cameras include Sony FX9, Canon C500 Mark II, and Panasonic S1H

APS-C sensors

• Smaller than full frame, with a crop factor of around 1.5x (varies by manufacturer)
• Offers a balance between image quality, cost, and lens compatibility
• Popular in mirrorless cameras and some cinema cameras (Sony FS5, Canon C300 Mark III)
• Allows for use of smaller, lighter lenses while maintaining good low light performance

Micro four thirds sensors

• Even smaller than APS-C, with a 2x crop factor compared to full frame
• Used in Panasonic GH series and Blackmagic Pocket Cinema Camera 4K
• Provides a deep depth of field and wide field of view with smaller, more affordable lenses
• Ideal for run-and-gun shooting, documentaries, and gimbal work due to compact camera and lens combinations

Super 35mm sensors

• Closely matches the size of traditional Super 35mm film (approximately 24.89mm x 18.66mm)
• Widely used in professional cinema cameras (ARRI Alexa, RED Helium, Sony Venice)
• Offers a good balance between depth of field control, field of view, and low light performance
• Many cine lenses are designed specifically for Super 35mm coverage

Sensor size effects

• The size of a camera's sensor has a significant impact on the visual characteristics of the captured image
• Understanding how sensor size affects field of view, depth of field, and low light performance is crucial for achieving desired creative results
• Cinematographers must consider sensor size when selecting lenses and planning shots to ensure the intended look is achieved

Field of view impact

• Smaller sensors (APS-C, Micro Four Thirds) have a narrower field of view compared to larger sensors (full frame, Super 35mm) when using the same focal length lens
• This is due to the crop factor, which effectively multiplies the focal length of the lens
• To achieve a wider field of view on smaller sensors, shorter focal length lenses must be used

Depth of field control

• Larger sensors allow for shallower depth of field at a given aperture and focal length compared to smaller sensors
• This is because the larger sensor requires longer focal lengths to achieve the same field of view, resulting in a more compressed perspective and shallower depth of field
• Smaller sensors, like Micro Four Thirds, have a deeper depth of field, which can be advantageous for maintaining focus in complex scenes or when using wider apertures

Low light performance

• Larger sensors generally have better low light performance due to their ability to gather more light and have larger individual pixels
• Full frame and Super 35mm sensors excel in low light situations, allowing for cleaner images at higher ISOs
• Smaller sensors, while still capable of good low light performance, may require faster lenses or higher ISOs to achieve similar results

Aspect ratios

• Aspect ratio refers to the proportional relationship between the width and height of an image
• Choosing the right aspect ratio is an important creative decision that can impact the overall look and feel of a film
• Different aspect ratios have become associated with certain genres, eras, and styles of filmmaking

Common video aspect ratios

• 16:9 (1.78:1) is the most common aspect ratio for HD video and television (1920x1080, 3840x2160)
• 17:9 (1.89:1) is used in some digital cinema cameras and is close to the traditional 1.85:1 theatrical aspect ratio
• 4:3 (1.33:1) was the standard for SD video and is still used for some stylistic choices (The Grand Budapest Hotel)

Anamorphic formats

• Anamorphic lenses optically squeeze the image horizontally during capture and require desqueezing in post-production
• Common anamorphic aspect ratios include 2.39:1 (CinemaScope) and 2.66:1 (Ultra Panavision 70)
• Anamorphic lenses produce distinct oval bokeh, lens flares, and a wider field of view for a given focal length

Choosing aspect ratio for story

• The choice of aspect ratio can greatly influence the viewer's perception and emotional response to the story
• Wider aspect ratios (2.39:1) can convey a sense of grandeur, scope, and immersion (Lawrence of Arabia, The Hateful Eight)
• Taller aspect ratios (4:3, 1.33:1) can create a feeling of intimacy, claustrophobia, or nostalgia (The Lighthouse, First Reformed)

Crop factors

• Crop factor is the ratio of a camera's sensor size to a full frame 35mm sensor (36mm x 24mm)
• It determines the effective focal length of a lens when used on a camera with a smaller sensor
• Understanding crop factors is essential for lens selection and achieving the desired field of view

Focal length multiplication

• To calculate the effective focal length of a lens on a cropped sensor camera, multiply the lens's focal length by the crop factor
• APS-C sensors have a crop factor of ~1.5x, meaning a 50mm lens will have an effective focal length of 75mm
• Micro Four Thirds sensors have a 2x crop factor, so a 25mm lens will provide a field of view equivalent to a 50mm lens on full frame

Lens selection considerations

• When choosing lenses for a cropped sensor camera, it's important to consider the desired field of view and the lens's designed coverage
• Wide-angle lenses for full frame cameras may not provide a sufficiently wide field of view on cropped sensors
• Lenses designed specifically for cropped sensors (Canon EF-S, Nikon DX) can be more compact and affordable while providing appropriate coverage

Achieving desired field of view

• To achieve a specific field of view on a cropped sensor camera, divide the desired full frame equivalent focal length by the crop factor
• For example, to achieve a 50mm full frame equivalent field of view on an APS-C camera (1.5x crop), use a 33mm lens (50mm ÷ 1.5 = 33mm)
• Keep in mind that the actual focal length of the lens remains the same, but the effective field of view changes based on the sensor size

Resolution and pixel density

• Resolution refers to the number of pixels in an image sensor, often expressed in megapixels
• Pixel density is the number of pixels per unit area on the sensor, which affects image sharpness and noise performance
• Higher resolution and pixel density can provide greater detail and flexibility in post-production, but also come with increased storage and processing requirements

Megapixel counts

• Common megapixel counts for video cameras range from 8MP to 20MP or higher
• 4K UHD resolution (3840x2160) equates to approximately 8.3MP, while 6K (6144x3160) is around 19.4MP
• Higher megapixel counts allow for oversampling, downsampling, and cropping in post-production

Oversampling benefits

• Oversampling involves capturing at a higher resolution than the intended output and then downsampling
• This process can help reduce aliasing, moiré patterns, and improve overall image quality
• Oversampling also provides flexibility for reframing shots or stabilizing footage in post-production

Downsampling for delivery

• Downsampling is the process of reducing the resolution of an image from its original capture resolution to the desired output resolution
• Capturing at a higher resolution (6K, 8K) and downsampling to 4K or HD can result in a sharper, cleaner final image
• Downsampling can also help to reduce noise and compression artifacts in the final delivery format

Large format advantages

• Large format refers to sensor sizes larger than Super 35mm, such as full frame and beyond
• These larger sensors offer several advantages over smaller formats, including shallower depth of field, wider field of view, and improved low light performance
• Large format cameras have gained popularity in recent years, with options like the ARRI Alexa LF, Sony VENICE, and RED Monstro

Shallower depth of field

• Larger sensors allow for shallower depth of field at a given aperture and focal length compared to smaller sensors
• This is because longer focal lengths are required to achieve the same field of view on a larger sensor, resulting in a more compressed perspective
• Shallower depth of field can help to isolate subjects, create a cinematic look, and guide the viewer's attention

Wider field of view

• For a given focal length, larger sensors provide a wider field of view compared to smaller sensors
• This allows cinematographers to achieve wider shots in tight spaces or with shorter focal lengths
• Wide-angle lenses designed for large format cameras can offer unique perspectives and creative possibilities

Improved low light performance

• Larger sensors have more surface area to gather light and can accommodate larger individual pixels
• This results in better low light performance, with cleaner images at higher ISOs
• Large format cameras are well-suited for shooting in dimly lit environments or when a natural, low-light aesthetic is desired

Smaller sensor benefits

• While large format sensors offer several advantages, smaller sensors like APS-C and Micro Four Thirds also have their benefits
• These include cost savings, lens compatibility, and portability
• Smaller sensor cameras can be ideal for certain shooting situations and budgets

Cost savings

• Cameras with smaller sensors are often more affordable than their large format counterparts
• Lenses designed for smaller sensors are also typically less expensive, as they require less glass and have a smaller image circle
• For productions with limited budgets, smaller sensor cameras can provide professional-quality results at a lower cost

Lens compatibility

• Many APS-C and Micro Four Thirds cameras have a wide range of native lenses available from various manufacturers
• These lenses are often more compact, lightweight, and affordable compared to lenses designed for larger sensors
• Adapters can also be used to mount lenses from other systems, providing even greater flexibility in lens choice

Portability and weight

• Smaller sensor cameras and lenses are generally more compact and lightweight than their large format equivalents
• This makes them well-suited for handheld shooting, gimbal work, and travel/documentary productions
• The reduced size and weight can also help minimize fatigue during long shooting days and allow for more discreet filming in certain situations

Matching sensor sizes

• When using multiple cameras on a production, it's important to consider matching sensor sizes for consistency in field of view, depth of field, and overall look
• Mixing sensor sizes can lead to challenges in post-production, such as differing crop factors and lens characteristics
• Careful planning and lens selection can help minimize these issues and ensure a cohesive final product

Maintaining consistency across cameras

• Using cameras with the same sensor size helps to maintain a consistent look and feel throughout a project
• This is particularly important when shooting with multiple cameras simultaneously, such as in multi-cam setups or for coverage in a scene
• Matching sensor sizes ensures that the field of view and depth of field remain consistent across all cameras

Lens choice for sensor size

• When using cameras with different sensor sizes, lens selection becomes crucial for matching the field of view and depth of field
• To achieve a similar field of view on a smaller sensor camera, a shorter focal length lens is required compared to a larger sensor camera
• It's important to consider the crop factor when choosing lenses to ensure the desired framing and look is achieved on each camera

Adapting lenses to different sensors

• In some cases, lenses designed for one sensor size may be adapted to work with cameras having different sensor sizes
• This can be done using lens adapters, which can help bridge the gap between lens mounts and sensor sizes
• However, it's important to be aware of any potential vignetting, changes in focal length, or reduced image quality that may result from using adapted lenses

Sensor size vs. film formats

• Digital sensor sizes are often compared to traditional film formats to provide a frame of reference for field of view and depth of field characteristics
• Understanding the equivalence between digital sensors and film formats can help cinematographers make informed decisions when transitioning between the two mediums
• It's important to note that while sensor sizes may be similar to film formats, there are still differences in image characteristics and workflow

Super 35mm equivalent

• Many digital cinema cameras, such as the ARRI Alexa and RED Helium, have sensors that closely match the size of Super 35mm film
• Super 35mm film has an approximate image area of 24.89mm x 18.66mm, which is similar to the sensor size of many professional cinema cameras
• This equivalence allows cinematographers to use lenses designed for Super 35mm film on digital cameras with minimal adaptation

65mm large format digital

• Some high-end digital cinema cameras, like the ARRI Alexa 65 and RED Monstro, have sensors that approach the size of 65mm film
• 65mm film has a significantly larger image area than Super 35mm, measuring approximately 52.5mm x 23mm
• These large format digital sensors offer similar benefits to 65mm film, such as shallow depth of field, wide field of view, and high resolution

16mm and Micro Four Thirds

• Micro Four Thirds sensors, with a size of 17.3mm x 13mm, are often compared to the 16mm film format
• 16mm film has an approximate image area of 10.26mm x 7.49mm, which is slightly smaller than Micro Four Thirds sensors
• The similar size and aspect ratio of these formats make Micro Four Thirds cameras a popular choice for achieving a 16mm film-like aesthetic in a compact, affordable package

Creative sensor size choices

• While consistency in sensor size is often desirable, intentionally mixing sensor sizes can also be used as a creative tool
• Cinematographers may choose to embrace the unique characteristics of different sensor sizes or use them to create specific visual effects
• It's important to understand the implications of these creative choices and plan accordingly in pre-production and post-production

Intentional crop for effect

• In some cases, cinematographers may choose to use a camera with a smaller sensor to intentionally crop the image and create a specific look
• For example, using a Micro Four Thirds camera on a project predominantly shot with Super 35mm sensors can create a more intimate or claustrophobic feel for certain scenes
• This technique can also be used to simulate the look of vintage lenses or film formats

Embracing limitations of format

• Each sensor size comes with its own set of limitations and characteristics, which can be embraced as part of the creative process
• For instance, the deep depth of field of Micro Four Thirds sensors can be used to create images with a more documentary or realistic feel
• The unique color science and low light performance of certain cameras can also be leveraged to create a distinct visual style

Mixing sensor sizes for look

• Intentionally mixing sensor sizes can be used to create visual contrast and guide the viewer's emotional response
• For example, using a full frame camera for wide, establishing shots and an APS-C camera for tighter, more intimate shots can help to create a sense of scale and depth
• Mixing sensor sizes requires careful planning in pre-production, on-set monitoring, and post-production to ensure a cohesive final look is achieved