What is an ORF file?

ORF is a container: a wrapper that holds streams encoded by something else. It stores a grid of pixels, so enlarging it past its own resolution softens it. It is used for photography and editing.

The extension is .orf, and the full name is Olympus Raw Format. Both matter less than what the file can hold, which is what the rest of this page is about.

Olympus published it in 2002. It comes out of Olympus and OM System bodies bodies.

Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.

Reading it outside the vendor’s own software depends on work done by other people, usually by inspection rather than by documentation. That mostly works and occasionally does not, which is the reason to convert anything you intend to keep.

ORF stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.

ORF has nowhere to record transparency. Anything transparent in the source is filled with a solid colour on the way in — white, unless something chooses otherwise.

Up to 12 bits per channel. It can work in RGB.

More than eight bits per channel is what stops a gradient from stepping when it is edited, which is why it matters in a working file and rarely in a finished one.

Adobe Lightroom, OM Workspace and darktable read it, and so do most programs of the same kind.

If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.

No browser reads it.

That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.

ORF can hold EXIF, XMP and GPS coordinates.

The GPS coordinates are the field worth thinking about before sending a file anywhere: they say where the photograph was taken, and almost nothing warns you that they are still in there.

ORF is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.

The recurring complaints: programs often show an embedded preview rather than the real data and support outside its home ground is uneven.

None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.

ORF is what Olympus and its successor OM System cameras write in raw — the OM-D and PEN bodies, the OM-1 and its descendants, and the older E-series DSLRs. Structurally it is a conventional manufacturer raw on a Bayer sensor, like Sony’s ARW or Nikon’s NEF.

The difference that matters is physical. Micro Four Thirds sensors are roughly a quarter the area of full frame, so each photosite collects less light. That does not change what the file is; it changes what the file is worth. The editing latitude a raw gives you is real here and smaller than the same latitude on a larger sensor, and it runs out sooner as ISO climbs.

Shadow recovery is where it shows first. Lifting three stops out of an underexposed ORF at ISO 200 works cleanly; the same operation at ISO 3200 surfaces colour noise that a full-frame file would not have shown. The raw file is still doing its job — there is simply less signal underneath it.

The practical consequence is that exposure discipline pays more here than on a larger sensor. Getting the shot right in camera and using the raw for fine adjustment is a better strategy than shooting dark and rescuing later, which is a workflow larger sensors tolerate.

This is the feature that makes ORF genuinely unlike other raw formats. The camera moves the sensor by half-pixel and whole-pixel steps between eight or sixteen exposures and combines them into one file — 50 megapixels on a 20-megapixel sensor when handheld, 80 on a tripod.

The result is a single ORF containing data no single exposure produced. Every photosite has real red, green and blue readings rather than interpolated ones, so colour detail is genuinely higher rather than merely upscaled. It is also why the file is several times the size of a normal frame, and why it fails in software that assumes a raw file has one exposure’s worth of data in it.

Converters that handle ordinary ORF correctly can refuse or mangle a High Res Shot file, because its dimensions and internal layout do not match what the demosaicing code expects. The symptom is usually an outright failure, occasionally a garbled image, and sometimes a file that opens at the sensor’s normal resolution rather than the composited one.

If a file that came off the same camera behaves differently from its neighbours, check whether it was shot in High Res mode before concluding anything is damaged. Olympus Workspace and the major raw editors handle it; smaller viewers and older tooling often do not.

Olympus recorded 12 bits per channel — 4,096 levels — well into the era when competitors had moved to 14. Recent OM System bodies write 14 bits, but a substantial share of the ORF files in existence are 12-bit, and they cannot be told apart from the extension.

Twelve bits is still four thousand levels against a JPG’s 256, so the argument for shooting raw holds comfortably. It does mean slightly less room before banding appears in a heavily pushed gradient, which is the one place the difference becomes visible rather than theoretical.

Live Composite builds a long exposure by adding only the parts of each frame that got brighter, which is why light trails accumulate while the ambient sky does not blow out. Live ND simulates a neutral density filter. Focus stacking combines several planes of focus in camera.

Each of these produces an ORF that looks structurally ordinary and is the product of processing you cannot undo. That is worth knowing before treating such a file as a negative: the raw file is raw sensor data, but it is raw sensor data from a computation rather than from one shutter actuation.

Olympus built its reputation on in-body image stabilisation, and it is genuinely exceptional — handheld exposures of several seconds are routine. The sensor is physically moving during the exposure to cancel your movement.

Nothing in the ORF records how well that worked. A file that looks slightly soft may be a stabilisation limit rather than a focus miss, and no amount of raw processing distinguishes them. Worth a moment before blaming the lens or the converter.

Camera model and serial number, lens, focal length, aperture, shutter speed, ISO, the exact date and time, the picture mode, and whether one of the computational modes was used. Location if the camera was paired with a phone or has a receiver.

Little of this survives a conversion to JPG or PNG in the way people assume — the exposure fields usually carry across and the location may or may not, depending on the tool. If the photograph is going to be published, that deserves a decision rather than an assumption.

To share or print, convert to JPG at high quality. For further work outside a raw editor, or where every pixel must survive, PNG or TIFF — and for a High Res Shot file, TIFF or PNG is the honest destination, since compressing 80 megapixels to JPG discards much of what the mode was for.

Keep the ORF regardless. The converted file has the white balance, the tone curve and the colour interpretation baked in permanently, and none of those can be revisited. For a High Res or Live Composite frame the original is doubly worth keeping, because it is the only record of something the camera cannot be asked to produce again.