Your camera sensor captures a bewildering amount of data, and by default, your camera makes some decisions on the fly and throws most of this data out. Consequently, a RAW image frame is like a film negative — different processing can give you different results.
Using a non-RAW format, like MPEG, is sort of like sending your film to the local drug store for processing. Maybe most of the time it’s fine, but sometimes you want the ability to go back and make your own decisions about things like white balance, sharpening, exposure, highlights, shadows, lens corrections and more.
Furthermore, uncompressed RAW video is everything coming off the sensor. When your camera throws out data to save on file size, this compression can (and does) lead to “artificating” (also called “compression legacies”). This most often appears as blocks in the shadow areas of your video.
Since your video is probably going to end up in a compressed format ultimately, some artifacting is inevitable. Like so many things it’s a balancing act between convenience and appearance.
When to skip RAW
If my mom texts and says “send me some video of that adorable cat of yours playing with that toy I knitted her,” I’d be a real jerk to send a six-gigabyte RAW camera file back. Your camera is fairly good at making average decisions about average lighting conditions for average use.
Similarly, if you’re shooting video simply for recreational purposes, shooting in MPEG is fine. RAW files are enormous and disk space, however-cheaper, is not free. So, if you’re sure you’ll never want to use this footage for something important, you’re probably ok not shooting raw.
RAW is really good at fixing video that was poorly shot in the first place. If you have a lot of control over your video setup — for example, if you’re able to set your white balance in advance and you know lighting isn’t going to change — you’re probably okay shooting MPEG.
RAW is really good at fixing video that was poorly shot in the first place.
Apart from being much larger, RAW requires post-production work to make it viewable; this is often a hindrance if you just want to get something out the door.
Likewise, if you’ve never shot RAW before don’t begin with an important project. The hardware requirements for RAW, especially in high resolutions, are significantly greater than for MPEG. SD cards that work fine for one format may not have the throughput for RAW. Test everything out first — which means taking 30 minutes or so of video to make sure your card and your camera’s buffer can handle all the data.
When to absolutely use RAW
RAW gives you so many options for changing the way your movie looks after you’ve shot it that any time you think you might want to combine footage shot at different places in different times or exert any creative control over what the final product looks like, RAW is what you should use. Other times when you’ll want to use RAW include when you’re unsure of your lighting conditions — whether you have mixed lighting sources or you’ll be moving between indoors and outdoors.
Make shooting RAW your default plan; you can always change it.
Occasionally I’ve shot video thinking that I’d had my camera set up to shoot RAW footage and come home to find a bunch of .mp4 files. If you spot Bigfoot lumbering through the forests of the Pacific Northwest, gingerly eating daffodil flowers, you’ll definitely want to grab RAW footage of that. But if you don’t start shooting immediately, you may miss it completely. You don’t want to have to fiddle with the camera.
For that reason, I try and leave all my cameras set to record RAW. That way, I have to make a conscious decision to switch (just remember to set it back when you’re done). That way you’re defaulting to the most options. If you find out you accidentally shot RAW when you meant to shoot MPEG, you can convert it.
Is there a middle ground?
There is a place between RAW and MPEG, called log — you can read about it here.
Certainly, if it’s important, shoot RAW. Similarly, if you think it might be important later, shoot RAW. If disk space is not an issue, shoot RAW. If you’re not sure, shoot RAW. You can always convert RAW to a format with a smaller file size, but you can’t go the other way. If it’s not earth-shatteringly important, or you know exactly how your lights will be set up, or you don’t want to do any post-processing work, MPEG is fine.
Kyle Cassidy is a writer and artist living in Philadelphia.