CAP Format Guide

Available Conversions

About CAP Format

CAP is an early RAW image format used by Phase One in their first generation of digital camera backs, primarily the P-series (P20, P20+, P21, P25, P25+, P30, P30+, P45, P45+). These digital backs were designed to attach to medium format camera bodies from Hasselblad V-system, Mamiya 645, and Contax 645 platforms, providing digital capture capabilities for existing film camera systems. CAP files store unprocessed sensor data at 14 to 16-bit depth from Phase One's CCD sensors, which ranged from 6 to 39 megapixels. The format predates the IIQ format that Phase One later adopted for their modern IQ-series digital backs, making CAP primarily a legacy format found in archives from the mid-2000s era of medium format digital photography.

History of CAP

Phase One introduced the CAP format alongside their early P-series digital backs in the early to mid-2000s. The P-series represented Phase One's first major push into the professional digital back market, competing with Leaf, Sinar, and Imacon/Hasselblad. The P20 (2004) offered 16 megapixels, while the P45 (2005) provided 39 megapixels — a remarkable resolution for that era. These backs used Dalsa CCD sensors and were widely adopted by commercial, fashion, and advertising photographers who needed the resolution and quality advantages of medium format digital capture. The CAP format served as the native RAW output, storing the full sensor data in a proprietary structure that was processed primarily through Phase One's Capture One software. As Phase One developed their next generation of digital backs — the IQ series, beginning with the IQ140, IQ160, and IQ180 — they transitioned to the IIQ format, which offered improvements in compression, metadata handling, and processing efficiency. The P-series backs were gradually discontinued, and the CAP format became a legacy standard. However, Capture One and several other RAW processors maintain support for CAP files, ensuring that photographers can still access and process their P-series archives.

Key Features and Uses

CAP files store unprocessed sensor data at 14 to 16-bit depth, preserving the full tonal range captured by Phase One's P-series CCD sensors. The format records the raw Bayer mosaic data along with metadata including exposure settings, white balance, lens information, and camera body identification. P-series CCD sensors, manufactured by Dalsa, were known for their clean low-noise performance, excellent color accuracy, and the smooth tonal rendering characteristic of CCD technology. The dynamic range of P-series backs ranged from approximately 11 stops (P20) to 12+ stops (P45+), which was competitive for the era. CAP files from the P45+ (the most advanced P-series back) produce 39-megapixel images at 7216 x 5412 pixels, with file sizes of approximately 80-120 MB per image. The format supports the full color gamut captured by the sensor, enabling precise color grading and retouching in post-processing.

Common Applications

CAP files are found primarily in professional photography archives from the mid to late 2000s, when Phase One P-series digital backs were widely used in commercial studios. Fashion photographers used P-series backs for editorial and advertising work, producing CAP files that were processed in Capture One for high-end retouching workflows. Product and still-life photographers relied on P-series backs for catalog and advertising photography, where the medium format sensor's resolution and color accuracy were essential. Studio portrait photographers appreciated the P-series CCD sensors' smooth skin tone rendering and excellent low-noise performance. Architectural photographers used P-series backs on technical cameras for high-resolution captures with perspective control. Converting CAP to modern, widely supported formats like TIFF, JPG, or PNG is essential for accessing and sharing these archival images, as CAP is a legacy format with limited viewer support. Capture One provides the best processing support for CAP files, while Adobe Lightroom and other RAW processors also maintain basic compatibility.

Advantages and Disadvantages