Multi-Spot Metering for Film

Why one spot reading is not enough

Spot meters read a one-degree angle. Point one at a face and that face becomes zone V, middle grey. Point it at the window behind the subject and the window becomes zone V, the face goes dark, the reading is useless. The meter is not wrong. It just does what you told it to.

No real scene has one tone you actually care about. A portrait has skin that varies from lit cheek to shadow side. A landscape has foreground you want detailed and sky you want textured. Multi-spot handles this by taking several readings and letting you decide how much weight each one gets.

The basic technique

Three readings is usually enough. One on the brightest tone you want with texture. One on the darkest shadow where you need detail. One on the main subject, whether a face, a rock, a doorway. Average those three and you have a workable starting exposure if all three matter equally.

They almost never do. In a window-lit portrait the face carries most of the decision. The shadow side matters but less. The window barely registers as a concern, though you do not want it blown. That is where weighting comes in.

Weighting by importance

Assign weights that match how much you care about each tone. A window-lit portrait might look like this:

• Lit cheek: 50 percent weight (the subject)
• Shadow side: 30 percent weight (detail matters)
• Window edge: 20 percent weight (do not want it blown, do not care if it is grey)

The weighted exposure lands closer to what the face actually needs. A plain average across all three would pull toward the window and underexpose the skin. The weighting corrects for that. That is the whole point of the technique.

Common multi-spot patterns

Portrait against bright background

• Subject face: 60 percent
• Important shadow on the subject (under collar, in eye socket): 20 percent
• Background: 20 percent

Landscape with sky and ground

• Foreground (where you want shadow detail): 50 percent
• Sky (where you want highlight texture): 30 percent
• Subject (the rock, the tree, the building): 20 percent

Studio portrait with controlled light

• Key-lit cheek: 50 percent
• Fill side of face: 30 percent
• Hair light or eye catch-light: 20 percent

Backlit subject

• Subject face: 70 percent (because the background is overpowering)
• Rim light on subject: 20 percent
• Background: 10 percent (mostly just to know if it will blow)

Multi-spot with the Zone System

Multi-spot dovetails into placement-and-fall. Take your weighted reading to get a base exposure, then check where each tone lands on the zone scale. If the brightest reading falls on zone X (no detail) and the darkest on zone 0 (no detail), the scene exceeds the film's latitude no matter where you place the middle. You have to choose what to sacrifice.

On negative film, place your shadow on zone III with the weighted reading and check where the highlight lands. If it lands above zone VIII, you have a contrast problem that development can address (N-1 or N-2). If it lands below zone VII, you might want to expand development (N+1).

When not to bother with multi-spot

• Flat lighting on average scenes. A single average reading on an overcast day is usually fine.
• Snapshot work. You will not always have time, and the cost of missing the moment is higher than the cost of a stop off.
• Slide film at golden hour. Bracket instead. Multi-spot tells you the centre of the bracket but slide film deserves three frames anyway.

Where Zone Light Meter helps

The multi-spot mode lets you tap multiple points on the live viewfinder, set a weight per reading, and see the weighted exposure plus the zone scale update in real time. Save common weight presets (portrait, landscape, backlit) so you can apply them with one tap. Each frame in the shot log records which spots you took and how you weighted them so you can replicate the workflow later.