What You Can Actually Fix in Post (and What You Can't)

"We'll fix it in post" is the most expensive sentence on a film set. Sometimes it's true. Often it means a day of work for something that would have taken thirty seconds on set. Here's where the line really is.

Cheap to fix

• White balance and colour, as long as the whole frame is lit by one kind of light. Log or raw gives you far more room than a baked-in profile.
• Moderate exposure errors. About one stop either way in log, less in compressed codecs. Underexposure costs you noise; overexposure costs you detail.
• Reframing, if you shot at a higher resolution than you deliver. 4K for an HD master gives you a free punch-in and a bit of slack on composition.
• Light stabilisation, at the price of a small crop.
• Steady background noise in audio, like air conditioning or fridge hum. Modern noise reduction handles constant noise well.

Fixable, but it costs hours

• Removing objects: a boom in frame, a logo, a sign. Easy on a locked-off shot, painful on a moving camera.
• Mixed colour temperature on a face, daylight from a window on one side and tungsten on the other. You can isolate and balance it, shot by shot, with masks and tracking.
• Flicker from a shutter that doesn't match the local mains frequency. Deflicker tools help, but not always all the way.
• Sky replacement and screen inserts. They look easy in tutorials and take a long time to look real.

Practically impossible

• Missed focus. Sharpening makes a soft shot look sharpened, not focused.
• Clipped highlights. If the sensor recorded pure white, there is no detail left to bring back.
• Clipped or distorted audio. Repair tools reduce the damage; they don't give you the clean take you didn't record.
• Wrong motion blur. A shutter far too fast gives choppy motion. Adding blur later rarely looks natural.
• Missing coverage. If the cutaway, the reverse or the wide doesn't exist, no software will invent it convincingly.
• A performance that isn't there. Editing can shape it, not create it.

A 60-second check before calling "cut"

1. Focus: punch in on the monitor and look at the eyes.
2. Highlights: zebras or false colour on the brightest part of the frame.
3. Audio: peaks well below 0 dBFS, no rustle on the lav.
4. Light: one colour temperature on the face, or a deliberate choice.
5. Coverage: do we have a way in and out of this scene?
6. Room tone: 30 seconds of silence on every location.

Thirty seconds on set saves an afternoon in the suite. That's the whole joke behind the name of this blog.