Does Sensor Size Matter?
The camera's sensor or film plane serves as the canvas on which light paints the image. It's an essential component that significantly influences the outcome of a photograph or video. Cameras come in various sizes and formats, each offering a distinct visual characteristic.
In the vast landscape of photography and videography equipment, the diversity of sensor sizes and formats can be bewildering. To navigate this complexity, let's delve into the five most prevalent motion picture formats, dissecting the impact of different sensor sizes on the final image.
Sensor sizes span a wide range, from the diminutive one-third-inch sensors found in smartphones and old camcorders to the massive 70x52mm 15-perforation IMAX film negative. To streamline our discussion, we'll focus on five formats that have stood the test of time and represent the core of film production.
While there are smaller formats like 8mm film and sizes in between, such as the Blackmagic 4K's four-thirds sensor, they remain less prevalent in professional film production. Our exploration will also be confined to video formats, excluding photographic image sizes like 6x6 medium format.
The smallest format commonly used is Super 16.
Its compact dimensions of approximately 7.4 by 12.5mm make it a cost-effective choice, requiring less physical film stock. Historically, Super 16 found favor in lower-budget productions. In the digital era, it's cherished for its optical properties. Its lower-resolution appearance and distinctive film grain evoke a nostalgic, documentary-style ambiance. Some digital cameras, like the original Blackmagic Pocket Cinema Camera, sport sensors that cover a similar area to the Super 16. Additionally, cameras like the Arri Alexa Mini offer specialized recording modes that sample a Super 16-sized portion of the sensor.
Stepping up in size, we encounter Super 35, the most prevalent format in the industry. This format is rooted in the dimensions of 35mm motion picture film, spanning approximately 21.9 by 18.6mm. The term "35mm" denotes the total frame width, encompassing the perforated edges on either side of the negative area. Filmmakers have the flexibility to vary the horizontal space they capture, depending on budget, aspect ratio, and choice of lenses. With spherical lenses, filmmakers may opt to crop the frame to conserve film stock or create a widescreen image. Conversely, anamorphic lenses that optically squeeze the image necessitate using the full sensor area, requiring later de-squeezing to achieve a 2.39:1 aspect ratio. Many digital cinema cameras, including the Arri Alexa Mini, the Red Dragon S35, and the Sony F65, adhere to this format. Consequently, Super 35 enjoys a wide array of compatible cinema lenses, offering filmmakers an extensive selection.
Moving further up the scale, we encounter large format or full-frame sensors. This format mirrors the 35mm image sensor format found in still photography DSLR cameras, such as the Canon 5D. It surpasses Super 35 in size, often measuring around 36 by 24mm. Cameras like the Alexa LF, Sony Venice, and Canon C700 FF fall into this category. The large format strikes a balance between Super 35 and the next size up, 65mm.
Historically, the 65mm format was based on 65mm gauge film, three and a half times larger than standard 35mm film, measuring 52.6 by 23mm with a widescreen aspect ratio of 2.2:1. The Alexa 65 boasts a digital sensor that aligns with 65mm film, providing a digital counterpart to this format.
Finally, at the pinnacle of motion picture formats
We find IMAX films. With a colossal 15 perforations, an IMAX frame blankets a vast 70.4 by 52.6mm image area. This format, due to its immense negative size and specialized cameras required for shooting, comes at a prohibitive cost, far beyond the budget of most productions. However, it has experienced a resurgence in recent years, especially in high-budget blockbusters by directors like Christopher Nolan, who champion its super high-fidelity film format.
Now, armed with knowledge about these five core formats, let's explore the intriguing effects and distinctions arising from their varied sensor sizes. The choice of format or sensor size significantly impacts several crucial factors.
Smaller the sensor, The Tighter the Result
First and foremost, it substantially affects the field of view. If you mount the same 35mm lens on cameras with Super 16, Super 35, and large format sensors, you'll notice that the smaller the sensor, the tighter the resulting image appears. Consequently, a large format camera offers a much wider field of view compared to a Super 16 camera, which produces a narrower view. This wider field of view also introduces a distinct sense of depth and perspective.
This divergence in field of view directly relates to the selection of focal length lenses required for each format. To compensate for variations in field of view, smaller formats like Super 16 demand wider-angle lenses to capture the same information, whereas larger formats necessitate longer lenses for an equivalent frame. For instance, to achieve the same field of view as a 35mm lens on a Super 35 sensor, a Super 16 camera would require a 17.5mm focal length, while a large format, full-frame camera would mandate a 50mm focal length.
The choice of format also exerts a noticeable influence on depth of field. Longer focal lengths inherently generate a shallow depth of field, where only a small portion of the image is in focus. Consequently, full-frame cameras employing longer focal lengths exhibit a shallower depth of field. This attribute proves beneficial in creating a pronounced separation between the subject and background, which contributes to a heightened sense of depth often associated with cinematic aesthetics.
However, this heightened separation comes with a drawback: it challenges the precision of the first assistant camera operator (1st AC) tasked with maintaining consistent focus. Smaller formats like Super 16, with their deeper depth of field, are more forgiving to focus pullers, offering a broader margin for error.
Additionally, the grain and resolution of the image are inherently influenced by the format size. Smaller formats typically yield more noticeable grain or noise textures, while larger sensors produce finer grain and exhibit greater clarity and resolution. Cinematographers occasionally opt for smaller gauge formats like Super 16 to intentionally introduce a textured appearance, while larger formats such as 65mm are favored for their pristine, low-noise, and sharp imagery.
Conclusion
In summary, the optical effects of choosing a format are profound. Smaller formats necessitate wider focal lengths, feature deeper depths of field, exhibit more pronounced grain, and often convey a flatter overall feel. In contrast, larger formats mandate longer focal lengths, resulting in shallower depths of field, exhibit less grain, offer greater resolution and clarity, and create a more three-dimensional look with an enhanced sense of depth.
Practical considerations also play a pivotal role in selecting a format. Generally, larger formats entail larger camera forms and higher shooting costs. Although this calculus may differ when comparing digital and film formats, within the digital realm, renting cameras and lenses for 65mm typically proves more expensive than opting for a Super 35 camera. In the world of film, the cost differential between 16mm and IMAX is staggering.
To address the fundamental question of whether sensor size matters, it's crucial to note that there's no unequivocal answer. Each format offers distinct effects and characteristics, making it suitable for specific creative endeavors.