14-bit capture

One of the things that comes with most high end DSLRs these days, but may be missing on the mid level ones is 14-bit capture. Some of the Nikons allow switching between 12-bit and 14-bit (sorry Sony, Olympus, and Pentax owners - I don't know enough about them). I've seen a lot of comments in reviews that it theoretically allows finer gradation in the shadows, etc. but had failed to produce an example of the difference it actually makes. Most people who have compared say they can't see a difference.

A comparison between the two on Earthbound Light does find a difference, but it also seems to explain why it won't make much difference for the majority of photos. My camera (Canon 40D) does have 14-bit capture and I haven't noticed a difference in shadow detail over the one I replaced (Canon 20D) - but given that I can't go back to 12-bit and save file space it is kind of a moot point for me. My take after reading on this subject is that it doesn't make much difference - unless you are seriously pushing exposure multiple stops. I suppose if you do a lot of low light shooting that may be an advantage, but I still think it is a very minor point when deciding on a camera. The bits are wasted on highlight detail (already enough) and noticeable in shadows only when pushed brighter.

Am I happy it is on my camera? Sure - drive space is cheap and it still shoots at 6fps so I can't really complain about speed. Have I noticed a difference in practical terms? No. Would I purchase a camera that 'only' had 12-bits for stock? Of course! (Keep in mind that JPEGs only have 8-bits in the end and there are a lot of very successful photographers that never touch a RAW file.)

I'd be interested to know how many people with the higher end Nikons leave their cameras in 12-bit instead of 14-bit...

Photo credits: Brad Calkins, Firststar, Kaja Maideen Rh.

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February 24, 2009


Wow - that is an exhausting article, but interesting nonetheless! Thanks for the link... The relationship between noise and banding, and hence why the extra bits don't help, was interesting.

January 27, 2009


A very interesting and exhaustive article on the subject of noise can be found here: http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html
I read most of it. I am an engineer and I am supposed to be passionate about it. It is a good read for the technical minded. Eventually the author reaches the same conclusion as you did. There is no difference for all practical purposes.
See: Noise, Dynamic Range, and Bit Depth:

January 14, 2009


14 bits means that between 0 and 1 there are 16384 "steps", while 12 bits only gives you 4096.
Assuming the sensor can deliver that kind of performance, having a finer sampling comes handy if you have to stretch a part of the histogram (to bring out detail in shadows or highlights) but it's effectively nearly invisible if the image does not undergo heavy post-processing.

It's a bit like CD vs SACD or DVD-Audio. The latter two deliver much better quality, but you need to stretch the media (i.e., play the media on a very high-end stereo system) to hear the difference.

Most people can do without, as the number of MP3 players sold every day clearly suggests...

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