With so many buzz words bouncing around the post world these days, it's hard to keep on top of them. New TV's are UHD, OLED, and HDR. Monitors are 10Bit, X-Percent Adobe RGB, and cameras shoot a countless number of formats. But with all the cool, trendy, terms being thown at us, it's hard to really boil it down to what's important.
Perhaps one of the most common features desired by cinematographers and colorists alike is the ability to shoot in "Log." You know, the type of video that looks grey and... well... crappy. But what the heck is Log? What's the advantage of shooting this way, and why should you care?
What is Log?
Let's start with some background.
Every camera, when it captures an image is basically graphing what it sees to certain values. A photo is just a HUGE set of those values.
Normally, we would think of a camera graphing the values something like this:
100% White = 100% White
50% Grey = 50% Grey
0% Black = 0% Black.
Graphing things like this would be considered a linear graph.
A Log graph works a little differently, it might be more like this:
100% White = 85% Grey
50% Grey = 63% Grey
0% Black = 22% Grey
The term "Log" comes from the name of the gamma curve used to record the image. Here's a really simple graphic to help this make sense:
What's the Advantage of Log?
The big advantage of recording in Log is to capture a greater dynamic range in your image. Here's how that works...
An image has a limited set of values. For the sake of simplicity, lets say an image's range i's 0-100. 100 would be the brightest thing in the image and 0 would be the darkest. The problem is, the world has a HUGE range of brightnesses. It ranges from pitch black to staring directly at the sun.
Because of the limits of camera sensors, file formats, and displays, we can only capture a limited range of these brightnesses. So when you expose an image, you're basically just picking a limited chunk to record.
Log recording pretty much just grabs a bigger chunk of brightnesses and squeezes it down to fit into the limited range of the image.
The Drawbacks of Log
So the advantage of recording Log is you have more dynamic range to play with in post. The disadvantage is you have to adjust the image for it to look decent.
Take a look at the image below. It was recorded using a linear curve. The bear looks pretty good, but the sky out the window is too bright and detail is lost in the branches of the tree.
Below is an image recorded in BMDFilm (Blackmagic's Log Format.) It looks bad. The shadows are lifted, the whites are just light grey. Not much saturation. But the image has good potential for adjustment in post because none of the color data is too bright or dark.
Below is the corrected Log image. Dark things are dark, bright things are bright. It looks nice, but it took a little work. The advantage is the detail retained in the highlights.
Should You Shoot Log?
So what's the bottom line? Should you shoot Log? Well, the answer would depend on the circumstances. Do you have time to process the images afterwards? Are you shooting in an environment where a higher dynamic range would be needed? You might be on a tight deadline where you don't have time to color grade, so shooting linear could be better. Just like anything, you have to weigh pros and cons.
That being said, I shoot some flavor of Log on nearly every project. I like it. But I'm a colorist, so color grading isn't that big of deal for me.
Want Some Help Color Grading Log?
If you like the flexibility of Log, you might consider picking up some LUTs that help you process your images fast. Here at Ground Control, we have tons of FREE LUTs made specifically for cameras that you use.
If you're wanting to get creative, check out some of our Creative LUT packs that are designed to take your Log footage and make it look awesome.
Shoot on a Sony camera? Here's our new pack of LUTs for S-Log2:
We also have tons of tutorials on color grading, including techniques for grading Log, Raw, and Rec.709 images!
Hope that helps shine some light on Log things. Let me know if you have any questions! Thanks for reading!
Ground Control makes LUTs. Awesome LUTs for color grading. Check out our products here.