How to open .PEF files (Pentax raw photos) on Android, Windows and Linux

Canon, Nikon and Sony raw files get most of the attention. But plenty of photos sit in less common raw formats: a Pentax K-series shoot, an old Samsung NX card, a Sigma’s Foveon files, or a studio’s medium-format archive. Many apps skip these entirely, and the camera maker’s software may be hard to find or no longer updated.

Here’s how to open a .PEF file and its rarer cousins. Nearly every raw file carries a preview image inside, and Folders shows it, for free, on Android, Windows and Linux. For real raw editing you’ll still want a raw editor, and this guide says which ones.

What is a .PEF file?

PEF stands for Pentax Electronic Format, the raw format of Pentax cameras (made by Ricoh Imaging), from the K-series DSLRs to the 645 medium-format bodies. Like most raw files it’s based on TIFF and holds the sensor data, EXIF details and a JPEG preview. Pentax is unusual in letting you choose: many of its cameras can save raw as PEF or as DNG, the open raw format. Files are usually named IMGP0001.PEF.

The rest of this family, in one table:

Extension	What it is
.pef	Pentax raw (Pentax DSLRs and medium-format bodies)
.srw	Samsung raw, from NX mirrorless and some compact cameras
.3fr	Hasselblad raw, from H-series and X-series cameras
.iiq	Phase One raw (“Intelligent Image Quality”), from medium-format backs and cameras
.mos	Leaf raw, from Leaf digital backs
.mef	Mamiya raw, from Mamiya digital cameras and backs
.erf	Epson raw, from the Epson R-D1 rangefinder
.dcr	Kodak raw, from Kodak’s professional DCS cameras
.kdc	Kodak raw, from some older Kodak cameras
.x3f	Sigma raw, from cameras with a Foveon X3 sensor
.rwl	Leica raw, from compacts Leica made with Panasonic, such as the D-Lux and V-Lux
.raw	A generic name used by older Panasonic and Leica cameras, among others

Two notes. Samsung left the camera business years ago, and its Galaxy phones save raw photos as DNG, not SRW. And .raw is a loose name: besides photos, it’s used for raw disk images, raw audio and data from scientific instruments, so a .raw file isn’t always a picture.

How to open a .PEF file with Folders

On Android

1. Install Folders from the download page and allow file access when asked.
2. Put the files on the phone if they aren’t there yet, for example from a card reader or a cloud folder.
3. Browse to them in Folders, or search for the file name.
4. Tap the file to open it in the image viewer. From another app, choose Open with → Folders.

On Windows and Linux

1. Install Folders for your system.
2. Open the folder in Folders and double-click the file.
3. On Windows, the installer registers Folders for every format in the table above, so File Explorer’s right-click Open with → Folders works too.

What you can do with it in Folders

• See the preview the camera stored, labelled RAW · embedded preview, with zoom.
• Read Details: camera, lens, shutter speed, aperture, ISO, focal length, date and location where recorded, plus the raw’s size in megapixels and the preview’s size. For Sigma X3F files, Folders reads these from the file’s own property list.
• Go through the folder with a swipe or the arrow keys.
• Share, rename, move or zip files from the file browser.

How much you see depends on the file. Most of these formats hold a large JPEG preview. Some medium-format files, such as certain Hasselblad 3FR and Phase One IIQ files, carry only a small uncompressed thumbnail; Folders shows that, but it will look small. If a file holds no preview at all, Folders says so and offers Open with another app.

For a generic .raw file, Folders looks inside for a JPEG preview. If the file isn’t a camera photo, there won’t be one, and you’ll need the program that made it.

Folders doesn’t develop raw data, adjust colour or exposure, or convert any of these formats.

Other ways to open .PEF files

• Digital Camera Utility: Pentax’s free software, based on SILKYPIX, for PEF and Pentax DNG.
• Phocus from Hasselblad (free) for 3FR, and Capture One (paid) for Phase One IIQ and Leaf MOS.
• Sigma Photo Pro, Sigma’s free software, which is often the most reliable way to develop X3F.
• RawTherapee and darktable: free raw editors for Windows and Linux with broad camera lists, including many older models.
• Adobe DNG Converter: free; turns most of these formats into DNG, which more apps understand.

Problems opening a .PEF file?

• The camera is too old for your editor. Kodak, Epson, Mamiya and early Samsung files aren’t always supported by current apps. RawTherapee’s long camera list or Adobe DNG Converter are good next steps.
• X3F won’t open. Sigma’s Foveon sensor records three layers of colour instead of a mosaic, and many popular raw editors don’t read X3F, especially from the Quattro models. Use Sigma Photo Pro.
• The picture in Folders is tiny. Some medium-format raws only carry a small thumbnail. The full image is there, but only a raw editor can render it.
• A .raw file shows nothing. It may not be a photo at all. Check where it came from: a disk tool, an audio recorder or a lab instrument each needs its own software.

Questions people ask

What opens a .raw file? If it’s a camera photo, Folders can show its preview, and RawTherapee or darktable can develop it. If it came from other software, use that software; .raw on its own doesn’t say what’s inside.

Can I convert PEF to DNG? Yes, with Adobe’s free DNG Converter. Many Pentax cameras can also save DNG directly, set in the camera’s menu.

Can I open Hasselblad 3FR files on Android? Folders shows the preview the file carries, with its details. Some 3FR files only hold a small thumbnail, so for a full-size view, use Phocus on a computer.

Is a camera raw file safe to open? Yes. Raw files are image data, not programs. Folders only reads the preview and details; it doesn’t run anything inside the file.

More raw guides: NEF and RAF, ORF and RW2. Or browse all 382 file types Folders opens.