The core problem: a multiple exposure stacks light. If you meter each layer normally, the combined frame is overexposed. So you both reduce exposure per layer and plan the alignment — and you have to write down what you did, because you can't see the result to learn from it.
Why double exposures need logging most of all
With a normal frame you can at least remember the scene. With a double exposure you're combining two scenes, often shot minutes or hours apart, with deliberate exposure compensation on each. There are simply too many variables to hold in your head — and no preview to jog your memory. If you want to reproduce a look, the log is the only record of the recipe.
The exposure math, briefly
Because two exposures land on the same frame, their light adds up. The usual fix is to cut each layer's exposure so the total lands where you want it:
- Two layers: reduce each by about 1 stop (−1 EV each).
- Three layers: reduce each by roughly 1.5 stops.
- Dark backgrounds help: a layer shot against black or deep shadow barely adds to the other, so it may need little or no reduction.
These are starting points, not laws — which is exactly why logging what you actually did matters. Your notes are how you turn "−1 each looked slightly hot" into "−1⅓ next time."
What to record for each layer
| Field | Why it matters |
|---|---|
| Layer 1 exposure | Aperture, shutter and the compensation you dialled in for the first pass. |
| Layer 2 exposure | Same again for the second pass — often a different scene entirely. |
| Total reduction | How much you cut each layer, so you can judge the blend afterwards. |
| Alignment plan | Where each subject sits — "portrait left, foliage filling the right." |
| Order | Which scene was exposed first; useful for how highlights and shadows stack. |
| Reference images | A snap of each layer so you can see what you were combining. |
A workflow for a planned double exposure
Decide the blend before you shoot
Pick your two subjects and where each should sit in the frame. A bright subject on a dark field is the most forgiving.
Set the per-layer reduction
Dial in −1 stop each for two layers as a baseline, more if you're stacking three. Note the numbers as you set them.
Shoot layer one and log it
Record its settings and a reference snap immediately, before you re-cock the shutter for the second pass.
Shoot layer two and log it
Same frame, second scene. Note its settings and how you aligned it against the first.
Review after developing
Compare the result to your notes: was the blend balanced? Adjust the reduction next time. This is where the log earns its keep.
How Film Logbook handles multi-exposure frames
Film Logbook logs frame by frame, which is exactly what a double exposure needs: record the frame's exposure, then use the frame's notes to capture the second layer's settings, your reduction and the alignment plan, and attach reference images of each scene you combined. Everything stays on that one frame under its roll, so when you develop, the full recipe is sitting next to the result — ready to repeat or refine.
It's free for up to two active rolls; a one-time €5.99 Pro unlocks unlimited rolls and PDF export. iPhone, iOS 15 or later.
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