Color bit depth

[Laxer17]

Hey so I'm trying to learn video right now and I'm a bit confused on this one particular topic. I know Color depth is measured in bits to show the values of rgb but I was confused on this one thing. 

I remember the BMCC came out a few years ago and was 10 bit which surprised everyone for it's price. I know most low level cameras shoot in 8 bit giving 256 values of rgb. 

I was scrolling across B&H and noticed the T6i's specs say 14 bit raw. Can anyone explain why this is thanks! 

https://www.bhphotovideo.com/bnh/controller/home?O=&sku=1116100&gclid=Cj0KEQjwouW9BRCN0ozIifTI6_cBEiQAD9gNsfVZfoyUBnuewoBdiHzXkYdHuNe1iOUZMZyFmcHEFtcaApD88P8HAQ&is=REG&ap=y&m=Y&c3api=1876%2C92051677442%2C&A=details&Q=

[Laxer17]

Like how can it shoot 14 bit for such a low price? 

[Evanair]

14 Bit raw is for photos, not the video side.

[Laxer17]

1 minute ago, Evanair said:

14 Bit raw is for photos, not the video side.

Thank you.

[Evanair]

http://nofilmschool.com/2012/10/why-dslrs-are-no-match-for-blackmagic-cinema-camera

 

Did a quick search, this should give you some insight about the difference between video camera and dslr.

[ALwin]

13 hours ago, Laxer17 said:

Hey so I'm trying to learn video right now and I'm a bit confused on this one particular topic. I know Color depth is measured in bits to show the values of rgb but I was confused on this one thing. 

I remember the BMCC came out a few years ago and was 10 bit which surprised everyone for it's price. I know most low level cameras shoot in 8 bit giving 256 values of rgb. 

I was scrolling across B&H and noticed the T6i's specs say 14 bit raw. Can anyone explain why this is thanks! 

https://www.bhphotovideo.com/bnh/controller/home?O=&sku=1116100&gclid=Cj0KEQjwouW9BRCN0ozIifTI6_cBEiQAD9gNsfVZfoyUBnuewoBdiHzXkYdHuNe1iOUZMZyFmcHEFtcaApD88P8HAQ&is=REG&ap=y&m=Y&c3api=1876%2C92051677442%2C&A=details&Q=

There are several reasons why bit depth for video and photo (RAW) are different.  Here's a few.

1. File size

A RAW file from even an old 6MP photo camera like a Nikon D70 is roughly 5MB in file size.  6MP is a bit lower in resolution than 4K (which is about 8MP), and approximately triple the resolution of FHD (which is about 2MP).  If recording video at 24fps, a single second of video could approximately be between 50MB-150MB in file size.  That's just for a single second, think of the size for a full minute of video or longer.

 

There are some cameras (like cameras from BlackMagic) that are capable of recording Cinema RAW or Cinema DNG files which are probably 12-bit or more, where each individual frame is actually saved as a "RAW" file on the memory card.  A BlackMagic URSA camera's 4K Cinema RAW file is on average around 7-9MB in file size.  That's why a camera like the 4.6K URSA Mini can only record a few minutes of RAW format video onto a 128GB memory card.  That would be a lot of storage space needed to film an entire feature length film using said camera with RAW format.

 

2. Most video cameras record to a color space that is called Rec.709 which is pretty much similar to sRGB.  8-bit color depth is sufficient to represent this color space fairly well.  10-bit would be capable of representing closer to something like AdobeRGB.

 

3. Processing power of whatever image processor (the brain) in the camera is capable of handling.  With a photo, you have to deal with only that one single moment captured in time.  With video, you need to deal with a series of moments that are captured across a period of time.  Unless you are dealing with Cinema RAW, you don't edit a video file the same way you may edit a still photo. Sure basic stuff like color correction will be similar, but you might do a lot more things to a still photo to bring out all the fine details or manipulate every part of an image while with video you won't be editing everything frame-by-frame..

 

And by the way, whether you record 10/12-bit video or 12/14-bit RAW photos, in the end the final output that you create for the audience is most likely going to be an 8-bit version.  The extra bits captured by the camera is the latitude you have in editing and grading the footage/image.