ARRI cameras are renowned in the film industry for their exceptional image quality, particularly their natural color rendition, pleasing skin tones, and wide dynamic range. This is largely due to the design of their ALEV sensors. ARRI sensors are known for having relatively large photosites compared to many other digital cinema cameras. Larger photosites generally have better light-gathering capabilities, leading to improved low-light performance and a higher signal-to-noise ratio. This translates to cleaner images with less noise, especially in the shadows.
The ALEXA 35 features a new Super 35 format sensor (ALEV 4) that boasts a claimed dynamic range of 17 stops. This is a significant improvement over previous ALEXA models. The increased dynamic range allows for even greater flexibility in capturing details in both the highlights and shadows, making it suitable for challenging lighting conditions. The ALEXA LF (Large Format) uses a larger sensor, providing a shallower depth of field and a wider field of view compared to Super 35.
ARRI's color science is a key component of the "ARRI look." It encompasses the entire image processing pipeline, from the sensor's response to light to the final image output. ARRI Wide Gamut (AWG) is the native color space of ARRI cameras. It's a very wide gamut, encompassing a larger range of colors than Rec.709 or DCI-P3. This allows for capturing a wider range of colors, which can be beneficial in post-production.
Log C is ARRI's logarithmic encoding. It's designed to capture the full dynamic range of the sensor in a way that's suitable for color grading. Log C has evolved over time, with different versions (Log C3, Log C4) offering subtle improvements. The ALEXA 35 uses the latest iteration of Log C, optimized for its new sensor.
ARRI Color Science (ACS) is the overall term for ARRI's image processing. It includes:
- Debayering: The process of converting the raw sensor data (from the color filter array) into a full-color image. ARRI's debayering algorithms are known for their quality, producing sharp images with minimal artifacts.
- Noise Reduction: Techniques to reduce noise in the image, particularly in the shadows.
- Color Transformations: The process of converting from the native sensor color space (AWG) to other color spaces (like Rec.709 or DCI-P3).
- Look Management: ARRI cameras allow for the application of Look Files (LUTs) to preview the graded image on set.
The ALEXA 35 features ACSv4, the latest version of ARRI's color science, which includes improvements to color fidelity, highlight handling, and overall image quality. REVEAL Color Science is the name ARRI gives to the complete image processing pipeline in the ALEXA 35.
ARRI cameras offer a range of recording options, catering to different production needs and budgets.
- ARRIRAW: This is the uncompressed raw data from the sensor. It preserves the absolute maximum image quality and provides the greatest flexibility in post-production. ARRIRAW is a "pure" representation of the sensor's output, bypassing most in-camera processing. It requires significant storage space and processing power.
- ProRes: Apple ProRes is a widely used intermediate codec. It offers various levels of compression, providing a balance between image quality and file size. Common ProRes options include:
- ProRes 422: A good balance of quality and file size, suitable for many applications.
- ProRes 422 HQ: Higher quality than ProRes 422, with less compression.
- ProRes 4444: Offers even higher quality, including an alpha channel (for transparency).
- ProRes 4444 XQ: The highest quality ProRes option, with minimal compression.
ProRes is a "baked-in" codec, meaning that some in-camera processing (like debayering and white balance) is applied before the image is encoded. However, it still offers significantly more flexibility than standard video codecs like H.264. ProRes is generally easier to work with than ARRIRAW, requiring less processing power.
The choice between ARRIRAW and ProRes depends on the specific needs of the production. For projects where maximum image quality and flexibility are paramount (e.g., high-end feature films, visual effects-heavy productions), ARRIRAW is the preferred choice. For projects where workflow efficiency and file size are more critical (e.g., television dramas, documentaries), ProRes is often a better option.