Log and linear (or raw) video files have their pros and cons, their supporters and detractors.
Some popular current hybrid video/stills cameras like the Panasonic Lumix GH4 come ready-equipped with Rec. 709 photo styles such as Cinelike D but logarithmic photo style V-Log L can be bought and added as an extra.
Other hybrid video/stills cameras like Sony’s a7S II come ready-equipped with a range of linear and log cinematic photo styles including S-Log3.
The ability shoot raw video has been one of the main attractions for cameras like the Digital Bolex D16 and Blackmagic Design’s cinema aka digital film cameras including the recently released URSA Mini.
More data does not always equate to better, though, and log is not always better than linear nor raw better than both. There are plenty of variables to consider, not least of which is whether you actually need maximum image acquisition data to get what you want.
Indie moviemaking guru Stu Maschwitz of Magic Bullet, The DV Rebels’ Guide and Prolost fame, has finally published a lengthy, information-packed article about log and raw video acquisition formats titled Raw is Not Magic and it is usefully illustrated with graphics, interactive image comparisons, and plenty of exploration of the positives and negatives.
Raw is Not Magic deserves in-depth study and thought. There is plenty to digest and Mr Maschwitz communicates his years of practical experience with log and raw very well.
Just one thing though. If you have or are considering purchasing a Panasonic Lumix GH4, or a Panasonic AG-DVX200 4K Handheld Camcorder, or are looking forward to the Panasonic Lumix GH5 making a possible appearance at PhotoKina 2016, it will be well worth your time to take a serious look at Visceral Psyche’s Leeming LUT One.
As the results being shown off at video industry forum DVXUser indicate, log or raw are not the only answers out there. Rec. 709 in combination with ETTR and the right conversion 3D LUT clearly have legs too.
“Raw Is Not Magic” says Stu Maschwitz. Compares with log to best aid your movie shooting choices. Click To Tweet
Raw is Not Magic
Via Prolost blog:
When you open an image from your digital SLR (or Cinema DNG files from something like the Blackmagic Cinema Camera or Digital Bolex) in something like Adobe’s Lightroom, and reduce the exposure to reveal a huge amount of information in the highlights — or radically adjust the white balance to recover a well-balanced image from a murky orange mess, it’s easy to feel that the raw files are somehow more than just pixels. It almost feels magic.
This sense of raw images being a true digital negative — deep, rich, forgiving of exposure errors, and massively tunable to your ultimate taste, leads some to feel that raw is always a better choice than the other common way of capturing a high-dynamic range cinema image: log.
“Log” is a broad term to describe images images stored with logarithmic (rather than linear or gamma-encoded) pixel values. You don’t see this format available often in still cameras (GoPro is a notable exception), but it’s commonplace in higher-end video cameras. The intent of log is similar to the intent of raw — to capture and preserve as much dynamic range as possible. Like raw, log images require post-processing to “look right.”
Cameras that shoot raw are great. But so are cameras that shoot log. A properly-recorded log image can be as powerful and flexible as a raw one, and can even have some advantages over raw.
And raw? It’s not magic — but the reasons it can feel that way are worth exploring.
The Double-Edged Sword of Linear Light
Raw images are typically stored in linear-light values. A reasonable definition of raw is “what the sensor captured,” and the sensor records light in light’s own measure, meaning that +1 stop = twice as much light = 2x the numerical value in a digital file.
This logical arrangement turns out to be inefficient as heck in any kind of quantized digital file. Half of your available tonal range is dedicated to the single brightest stop of your image, so raw files have to have very high bits depths to hold detail in the low exposure areas. It’s not unusual for raw files to be 12- or 14-bit. But it’s not useful to directly compare those numbers against the bit depths of log or video encoded files, where the tonal range is distributed non-linearly.
Read full article at Prolost blog “Raw is Not Magic”
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(cover photo credit: snap from source in post)
Karin is a documentary moviemaker, journalist, photographer and teacher who conceived and cofounded an influential, globally-read, Australian magazine of contemporary art, culture and photography. While based in Europe, contributing to the magazine and working in advertising, she visualised a future telling the same sorts of stories with a movie camera and audio recorder. Now back in her home base in Sydney, Karin is pursuing her goal of becoming an independent, one-person, backpack multimedia journalist and documentary moviemaker. Mentorless and un-filmschooled, she is constantly learning and sharpening up her skill set.