Camera RAW
What is an ERF file?
Updated Jul 2026
ERF (Epson RAW) is the raw image format written by Epson digital cameras, such as the Epson R-D1 rangefinder. It stores the sensor's unprocessed data losslessly, so nothing is discarded the way a JPG would discard it. The catch is that most photo viewers, editors, and websites don't recognize ERF, so it usually needs converting before you can do much with it.
- Extension
- .erf
- Type
- Camera RAW
- Typically
- Epson cameras
- Metadata
- Carries EXIF
Why ERF exists
ERF comes from Epson's short run of digital cameras in the mid 2000s, most notably the R-D1 and R-D1s rangefinders. Like other camera makers, Epson built its own raw format instead of using a shared standard, so ERF only shows up if you shot with one of those specific cameras.
Because it's a raw format, an ERF file holds the data straight off the image sensor before the camera applies sharpening, color balancing, or compression. That gives you more room to adjust exposure and white balance after the fact, at the cost of a much larger file than a JPG from the same shot.
People run into ERF today mostly when going through old photo archives from an Epson camera. Support for the format is thin: current photo apps, phones, and most websites won't open it directly, so the usual fix is converting it to a JPG or TIFF to actually view or share it.
The trade-offs
Strengths
- Keeps the full sensor data with no lossy compression
- Leaves more room to adjust exposure and white balance later
- Preserves the original capture for archival purposes
Watch-outs
- Very limited support outside old Epson-specific software
- Large file size compared to JPG
- Can't be viewed or shared until converted
A note on privacy
An ERF file carries EXIF metadata from the camera, including the date, time, and shooting settings, and sometimes location data. Uploading it to a browser-based converter sends that whole file, metadata included, to someone else's server. Converting it on your own machine keeps the photo and its metadata local the entire time.
Questions
How do I open an ERF file?
Most modern photo viewers and editors don't recognize ERF. You'll generally need to convert it to a common format like JPG or TIFF first, since native ERF support was mainly limited to software from around when the R-D1 was current.
Is ERF better than JPG?
For editing flexibility, yes: ERF keeps the raw sensor data so you can adjust exposure and color more before quality suffers. For everyday viewing and sharing, no: JPG opens everywhere, and ERF opens almost nowhere without converting first.
Why does my camera save ERF files?
If you shot with an Epson R-D1 or R-D1s, the camera saves raw captures as ERF by design, since that was Epson's own raw format for those models. There's usually no in-camera option to save as anything else.
Can I convert ERF without uploading it?
Yes. A desktop app like Morphjet converts ERF files on your own computer, so the image and its embedded metadata never leave your machine.
Morphjet opens and converts ERF and 1,800+ other formats, all on your own computer. Launching this July.