In this premiere episode of our new series “1,024 Shades of Grey,” we learn from experienced pro Alister Chapman of XDCAM-User.com who argues that Log is not the answer to every problem – especially in low light.
We created this series because people with vastly more experience than most of us are often willing to share their hard-won scar tissue, sometimes with surprising results.
I was impressed.
He said a number of very interesting and unconventional things, and I wanted to learn more. His comments are especially relevant as I edge closer and closer to my next camera, which will be 4K and have some kind of log setting.
Most interesting of all for me as a newbie to 4K and log recording is his assertion that one should NOT shoot log in low light.
Take a read and tell us what you think in the comments below.
If shooting in low light don’t use Log!
One common question I am often asked is how to use Log or CineEI in low light situations. After all in the Sony CineEI mode or with a log camera such as the Alexa that use EI the actual recording gain is fixed, so often the recorded pictures are very dark. So what should you do?
My answer in many cases is simply not to use Log or EI. It’ really important to remember that the primary reason why log recording was developed was to make it possible to record a very large dynamic range using existing recording technologies. In order to do this lots of compromises are made. The main one being allocating less recording data to each stop of dynamic range. If you’re recording using 10 bit you typically have about 970 useable code values or shades. Use a gamma curve with 6 stop range and you have about 160 shades per stop, record using a log or other extended range gamma with a 14 stop range and you have just 70 shades per stop.
Lets think about a couple of different scenes for a moment. Scene one is a daytime scene that’s nice and bright with an 8 stop dynamic range. Scene 2 is a night time scene that is fairly dark and only has a 5 stop dynamic range. What happens if we shoot using log?
With the daytime scene things are pretty straight forward. You just expose as per the manufacturers recommendation. Assuming your camera is set to log and capable of a 14 stop dynamic range, if exposed at the base, recommended exposure levels you will be using a little under 60% of your available recording range, so a fair bit of data will be going to waste.
Read full article at XDCam-User “If shooting in low light don’t use Log!”
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(cover photo credit: snap from XDcam-User)