More about converting MOS to JPG
MOS is the RAW format used by Mamiya Leaf medium-format digital backs - the Aptus, Aptus-II, Credo, and the Mamiya Leaf Credo line that mounted on Mamiya 645DF, Phase One XF, and Hasselblad H bodies. Resolutions run from 22MP (Aptus 22) up to 80MP (Credo 80, IQ180). Commercial product photographers shooting watches and jewelry for Tag Heuer or Tiffany, automotive shooters working with Mercedes and Porsche press fleets, and luxury real-estate teams photographing $20M Aspen and Hamptons listings convert MOS to JPG for client previews and approvals.
Capture One Pro is the de facto MOS processor because Phase One acquired Leaf in 2014 and integrated MOS support deeply. Lightroom reads MOS via LibRaw but lacks the per-back profiles Capture One provides, which matters for skin tones in cosmetics shoots and the chrome highlights in automotive work. A Credo 80 MOS file is 80-110MB; converting to JPG quality 95 for client web galleries produces 18-28MB files that ProofSheet and PhotoShelter can serve as full-screen previews while keeping the masters in the studio's NAS.
Architectural firms working with Bjarke Ingels Group or Foster + Partners commission medium-format shoots in MOS, then convert to JPG for renderings, RFPs, and competition boards. The IQ4 150MP back produces 200MB MOS files; quality-92 JPG export at 8192px long edge lands around 35-45MB, retaining enough resolution for billboard reproduction or the 24x36-inch portfolio prints architects deliver to award juries. Color management throughout: AdobeRGB for print, sRGB for web preview only.
When you'd use this
Reasons to convert MOS to JPG usually come down to compatibility, file-size, or specific feature requirements. Common situations:
- An app or platform only accepts JPG uploads.
- You need a feature unique to JPG (e.g. transparency, vector scaling, animation, multi-page pages, etc.) that MOS doesn't provide.
- You're optimising file size — modern formats often produce smaller files than the older format you started with.
- You need a single archival format across a project so files behave consistently in the same viewer.
How to do it in jpg.now
- Open the MOS → JPG tool on jpg.now.
- Drag your MOS file onto the drop zone, or click Select files. You can drop a whole folder of files at once.
- The output is fixed to JPG. If the format supports extra options (page size, transparency background, quality, EXIF stripping), tweak them in the right-hand panel.
- Click Convert. The job runs on our server and finishes in a few seconds for typical photos.
- Download the result. Files stay in storage for 24 hours and are then permanently deleted.
The entire flow is free for the first 10 jobs per day with no signup required. A free account doubles that quota; a premium plan removes the limit entirely.
Tips and common pitfalls
- Use Capture One Pro - it is the only application with native per-back profiles for every Leaf Aptus, Credo, and Phase One IQ back, plus correct color science.
- Apply lens cast correction (LCC) before JPG export on wide-angle backs - the 28mm Schneider on a Phase One XF has heavy magenta cast that LCC eliminates.
- Export at 16-bit ProPhoto TIFF first for the retoucher, then derive JPG quality 92 sRGB for client web preview - never go RAW direct to web JPG on commercial jobs.
- Strip back serial number and shoot date from EXIF before client delivery - reveals studio scheduling and rental gear that competitors sometimes scrape for intel.
- For 100MP+ backs, use the export resize at 8192px long edge for web preview JPG - keeps the file under 40MB while supporting retina display zoom and crop.