Alex Tutubalin of RawDigger has some interesting findings on the new Canon 5D Mark IV:
- Canon Dual Pixel Technology: Gaining Additional Stop in Highlights
- Canon 5D Mark IV Dual Pixel Mode. Oh Yes, Highlights Are There!
Dual Pixel stuff looks very promising feature if properly supported in raw processing software.
Each pixel is divided in two parts, left and right, each looks into left and half sides of the lens. Primary usage is to allow phase autofocus on sensor (for video), but when combined and one half parts are stored separately in RAW this allows some interesting features:
As advertised in Canon materials:
- Slight refocusng after shot (because each half of pixel is effectively shot at extra aperture stop, so DOF is deeper. Refocused image looks not ideal sharp, but this may save slightly wrong focused image)
- Possible to remove flare if it come from one side of lens (left or right, not top or bottom)
- Possible to build image 'depth map' (by phase difference on two halves) and add additional blur on out-of-focus areas, creating more 'bokeh'.
Not advertised, but looks possible in some cases
- Extra stop in highlights ('half' part is one stop lower than combined, while data range is the same)
Not advertised, needs more testing:
- in focus areas are not 'phase shifted' in pixels halfs, this may allow extra resolution in sharp areas (effectively up to 60Mpix).
For the price:
- doubled file size
- lower burst FPS
- lower burst length (?? not sure, buffer size for dual-pixel raws not mentioned in manual, while lower burst FPS is)
Noise is not increased, because 'A+B' data looks digitized the right way (combined before ADC used).
We have only two samples with this feature enabled, so all findings about one extra stop are based on these two files (but looks very promising with second sample with blown out sky).
Do not know what possibilities will be supported for raw converters. Adobe promised 'support' in LR/ACR, but no details.