RAW Uncompressed, Lossless Compression, and Lossy Compression: Read the Manual by Model
Based on the official manuals of the Fujifilm X-T5 and Sony ILCE-7RM5, explain RAW compression modes, file sizes, and applicable scenarios, without generalizing manufacturer specifications or unverified assumptions as universal rules.
RAW Compression Options Depend on Camera Model
The "Uncompressed," "Lossless Compressed," and "Compressed" options in a camera's menu are not offered under the same names or combinations on all models. For example, the Fujifilm X-T5 manual lists three items: Uncompressed, Lossless Compressed, and Compressed, defining the latter two as reversible lossless and irreversible lossy compression, respectively.〔G-RAW-COMP-01〕
X-T5 Notes on Compression Ratios and Image Quality
Fujifilm states that the X-T5's lossless compressed RAW has the same image quality as uncompressed RAW, with files about 30%–90% the size of uncompressed files. Lossy compression is irreversible, with files about 25%–35% the size of uncompressed files, and the manual describes the image quality as "about the same." These ranges and descriptions are given in the model's manual; they do not represent a fixed compression ratio for each photo, nor do they constitute independent image quality testing.〔G-RAW-COMP-02〕〔G-RAW-COMP-03〕
Sony's Naming and File Size Examples
The Sony ILCE-7RM5 manual also lists Uncompressed, Lossless Comp, and Compressed. It notes that lossless compressed files are smaller than uncompressed files, while lossy compressed files are about half the size of uncompressed files; the M / S size options for lossless compression reduce the output image resolution. Do not directly apply Sony's roughly half-file-size ratio to Fujifilm or other camera models.〔G-RAW-COMP-04〕
Do Not Infer Burst Performance or Post-Processing Limits from File Size
Manufacturer manuals can confirm the compression methods, supported options, and the indicated file size ranges; relying solely on this information cannot determine buffer clearing times, burst capacity, star edge artifacts, or shadows' dynamic range limits on any storage card. These issues should be evaluated using the corresponding model, firmware, card, and real-world scenarios for comparison testing. This article only retains format and size information explicitly provided in the official manuals.
This guide has completed authoritative technical literature source registration and field-level claim verification, and is included in the publication layer and site search index.
Associated Entities & Verification Exits
Relationships are only displayed when verified; unverified links remain empty.