You might assume your RAW processing software shows you everything captured by the camera, but that’s not always the case. Where the camera is applying digital lens corrections, there may be more ‘image’ outside the regular image area that you wouldn’t normally see.
This extra image area has been captured by the camera’s lens and sensor but discarded by the firmware as being outside of the design parameters of the lens and camera’s digital corrections… or simply doesn’t fit the camera’s native aspect ratio.
It depends on your RAW processing software. All processors will respect the image crop embedded in the photo by the camera, but sometimes the software will be able to show the wider image area still present in the RAW file.
The image in this example shows this taken to the extreme. It was shot on a Panasonic TZ200, a camera with a 1-inch sensor that has a 3:2 native aspect ratio and a 15x optical zoom.
This extended zoom range is made possible by the camera’s digital lens corrections, which are embedded not just in its JPEGs but in its RAW files too. These have an embedded crop that excluded distorted areas outside the corrected image area. Most RAW processors respect this embedded crop, as does Capture One, but where Capture One differs is that it will also display the image area outside the crop.
1. The embedded image crop
This is a RAW image opened in Capture One. It looks undistorted and perfectly normal. If you take a look over at the thumbnail browser on the far right, however, you’ll see that the thumbnail looks far from normal. It actually shows a far wider image cropped to a central portion (Capture One always displays cropped areas in its thumbnails).
2. The ‘hidden’ image areas
Sure enough, if I swap to the Crop tool, I can see in the main Viewer window that there are large areas of image outside the default crop area. They might be distorted and unusable, but I won’t know until I manually extend the crop boundaries.
3. The full ‘uncropped’ image
This is very interesting! It turns out that the camera has actually captured a much wider angle of view than it displays. Unfortunately, in this instance the extra areas are heavily distorted – it’s an indication of the extreme design used by Panasonic for this lens, and the extreme corrections it’s using to produce undistorted images across this zoom range. It’s pretty obvious that while I can steal a little extra undistorted height from the image, and just a little from the edges, the distortion quickly takes hold and renders the outer edges unusuable.
So just how useful is this?
It depends on the camera and the lens. Generally, I’ve found that this extra crop area is revealed only with cameras that embed correction data directly in the RAW files – typically mirrorless cameras and high-end compacts – and you can only recover extra image area at or near the lens’s shortest focal length.
Some lenses cut it pretty tight. I have a Sony E 18-135mm f/3.5-5.6 which is a great lens but leans very heavily on its digital corrections. I can squeeze a little extra image area out of wideangle shots, but the corners quickly darken in a way that vignetting corrections can’t fix.
I also have an Olympus M.Zuiko 12-40mm f/2.8 Pro lens which offers about 20% extra image area at its wideangle setting in Capture One and without distortion. I can get a little extra in DxO PhotoLab too. These are not insignificant differences. It means that the Olympus’s 24mm equivalent lens can actually deliver an angle of view closer to at 22mm or 23mm lens.
The other time I have found this really useful is with my favorite travel camera, a Fujifilm X-30. Its 28mm equivalent widest zoom setting is often not quite enough, but Capture One can reveal just that little bit more at the edges – and also delivers a slightly wider aspect ratio in the process. That’s fine by me because I find the X30’s native 4:3 ratio a little ‘oversquare’ for horizontal format images.