Why your takes changed colour between shots
The framing matched perfectly and the cut still looked fake. The camera had quietly re-metered the room while I walked out of it.
Alignment was the problem I expected to spend my time on. Get the ghost frame over the viewfinder, line the shot back up, cut. Solved.
Then I made a cut where the framing was pixel-accurate — I checked, it was within a couple of pixels along every edge — and it still looked obviously edited. The shelf was in the same place. The shelf was a different colour.
Auto exposure is doing its job
Between take one and take two, I walked out of frame. My body had been occupying maybe a fifth of the shot, and it was the darkest fifth. With it gone, the average scene brightness went up, and the camera did exactly what it is built to do: it re-metered, pulled exposure down, and re-balanced white against a scene that was now mostly a teal wall instead of mostly a person.
Both takes are correctly exposed. That is the trap. Neither frame looks wrong on its own. Played back to back they look like two different afternoons, and the viewer clocks it instantly even though almost nobody can articulate what they saw.
The same thing happens with:
- a lamp that clicks off between takes
- a cloud, which is not on your schedule
- moving a bright object out of frame, which is often the entire point of the shot
- the camera’s own gradual settling after focus
Locking it
The fix is to stop the camera making a fresh decision. PoseCut pins exposure and white balance to whatever the first take of a project settled on, and every subsequent take in that project inherits the pin.
The important word is first. Locking at some fixed neutral value would be worse than useless — it would blow out a bright room and crush a dim one. What you want is the camera’s own judgement, made once, and then held.
There is a deliberate consequence: the second take can genuinely be under-exposed. If you switch a lamp off between takes, the app will not brighten the second half to compensate. It will show you a darker room, because a darker room is what is there. That is correct behaviour for a cut that has to read as one continuous shot, and it is a surprise the first time it happens to you.
Settling
The other half of it is timing. Tap record the instant the capture screen appears and you catch the sensor mid-adjustment — the first handful of frames drift as focus and exposure converge, which puts a visible ramp at the head of your clip.
So the record button does not arm until the preview has been stable for a short beat. It is a small delay, and I went back and forth on whether it was patronising. It stayed in, because a clip whose first ten frames are visibly settling is a clip you have to trim by hand every time, and trimming it by hand eats the hold that the seam wants.
What is still not handled
Rolling shutter and any real motion in the background — traffic, leaves, a television — are unfixable at the join. Two takes recorded ninety seconds apart have different cars in them, and no amount of exposure locking changes that.
The current answer is honest and unsatisfying: frame away from moving backgrounds, or make the moving part of the frame small enough that nobody is looking at it. The app cannot fix the world behind you. It can, at least, stop the camera from making the problem worse.