Camera tests and look development

A look book describes the intended image; tests prove it. Camera and lens tests, makeup and wardrobe tests and look development sessions with the colourist turn references into a working pipeline that will produce the right image every day on set. Tests also prevent expensive surprises: a lens that flares badly in the film's key night exterior, a costume that turns an unexpected colour under sodium street lights, a LUT that crushes darker skin tones. This lesson explains what to test, how to design tests so they answer real questions, how the LUT pipeline carries the look from camera to dailies to the final grade, and how to monitor exposure on set with consistent targets.

Why test

Testing costs time and money in prep, which is why it is sometimes squeezed. It is almost always cheaper than discovering a problem during production.

• Confirm that the camera, lenses and filters produce the look in the look book.
• Learn how the camera behaves at the exposure extremes the film will use, such as deep night or bright snow.
• Let costume, makeup, hair and production design see their work through the actual camera and look.
• Build and validate the show LUT and the colour pipeline before day one.
• Check technical requirements: delivery specs, VFX needs, data rates and storage.

Every test should start with a question. "Test the lenses" is not a question. "Which of these two lens sets renders Maya's close-ups more gently at T2 in tungsten light, and how much do they flare with a practical in frame?" is.

Camera and exposure tests

Course CINE-202 covered how sensors, log curves and dynamic range work. In a narrative prep, an exposure test checks the specific camera, settings and LUT the production will use.

• Latitude test: shoot a chart and a person at normal exposure, then at one-stop intervals over and under, from about four stops under to five or six over. Grade each back to normal in the intended pipeline and judge noise, colour and highlight behaviour.
• Exposure index (EI) choice: many digital cameras let you rate the sensor at different EIs; rating higher protects highlights, lower reduces visible noise. The test shows which rating suits the film.
• Mixed light: test skin under the film's real sources, such as tungsten practicals, LEDs, fluorescent tubes or street lights.
• Frame rate and shutter: check flicker with any practicals, screens or LED fixtures that will appear in shot (Course CINE-340).

Record every setting in a test log: camera, firmware, EI, white balance, lens, stop, filters, frame rate, shutter and LUT.

Lens tests

Lens tests compare candidate sets and check each individual lens. Rental houses usually allow test days in their prep bays.

• Character: sharpness, contrast, flare, bokeh, distortion and colour rendering across the set.
• Matching: lenses in a set should match closely in colour and contrast so cuts between focal lengths are invisible.
• Mechanical checks: focus scale accuracy against measured distances, back focus or flange depth, smooth rotation of focus and iris rings, and breathing (the change in image size when focus is pulled).
• Flare and practicals: shoot with a bare bulb or the sun at the edge of frame.
• Close focus and minimum object distance, important for inserts.

The camera assistants usually run the mechanical checks; the DP judges the image. Testing at the stops the film will actually use matters, because many lenses behave very differently wide open than stopped down.

Makeup, hair and wardrobe tests

These tests put actors, or stand-ins with similar complexions, in front of the camera in costume, makeup and hair, under light similar to the film's key scenes.

• Check how makeup reads at the intended sharpness and with any diffusion; shine, texture and colour all change on camera.
• Check costume colours and fabrics under each lighting condition. Some synthetic fabrics change colour under infrared contamination or certain LEDs; very fine patterns may cause moiré.
• Check hair under backlight and with the planned diffusion.
• Light and expose for every member of the cast. A setup that renders one actor beautifully may need a different fill or exposure approach for another, and the test is where you find out.

Course CINE-310 discussed the history of imaging systems biased toward lighter skin and the craft of rendering every complexion well. Tests are where a DP proves that the lighting approach, exposure targets and LUT work for the whole cast.

The colour pipeline from camera to grade

A pipeline describes how the image is transformed at each step. The goal is that the director, editor and producers see a consistent preview of the look throughout production, and that the colourist starts the final grade from the same intent.

• Camera: records log or raw footage with metadata. The camera also outputs a monitoring signal with a LUT applied.
• On-set monitoring: the DIT applies the show LUT and, often, per-scene adjustments stored as a colour decision list (CDL), a simple standard set of slope, offset, power and saturation values.
• Dailies: the lab or near-set dailies system renders editorial media with the LUT and CDLs applied, plus synced sound.
• Editorial: the editor cuts with the dailies look.
• Final grade: the colourist starts from the camera originals, uses the same LUT or colour management (often ACES or a camera-specific scene-referred workflow) and CDLs as a starting point, and refines the look.

Building the show LUT

The show LUT converts the camera's log image into a viewable image with the film's look. It is usually built by the colourist or DIT in prep, using test footage.

• Start from a technically correct transform for the camera and display, then add the creative look: contrast, colour bias, saturation and highlight roll-off.
• Keep the LUT gentle. A heavily stylized LUT can make exposure hard to judge and limits options in the grade.
• Check the LUT on all the test material: every skin tone, day and night, interiors and exteriors, highlights and deep shadows.
• Version the LUT clearly (for example SHOW_v03) and make sure the camera, monitors, DIT and dailies all use the same version.

Some productions use a small family of LUTs, such as one for day and one for night, rather than one LUT for everything. More LUTs add flexibility but also more chances for mistakes, so keep the family small and well documented.

Monitoring exposure: false colour and waveform targets

With the look defined, the DP needs consistent exposure targets so scenes shot days apart match. Two tools dominate: the waveform monitor, which plots brightness across the frame, and false colour, which paints brightness ranges in fixed colours over the image. Course CINE-202 explained how these tools read log and display signals. In narrative prep, the DP sets targets for the specific camera, LUT and look.

• Decide whether you judge exposure on the log signal or through the LUT. Many DPs judge key elements, such as faces, through the LUT and check highlights and shadows on the log waveform.
• Learn your camera's false colour key: which colours mark clipping, mid-grey, skin range and black.
• Set targets by scene type: a day interior key, a night exterior key, a low-key dramatic close-up.
• Use the targets as a starting point, not a cage. A deliberately dark scene may place faces well below the normal range.

Designing a test day

Test days are short and expensive, so design them carefully. A typical prep might include one or two camera and lens days and one makeup and wardrobe day.

That is 8.5 hours of activity before set-up and breaks, so a test day needs a 10- to 12-hour booking or careful trimming. Prioritize the tests that answer the most expensive questions.

In Canada, rates are quoted in Canadian dollars and GST or HST applies to most rentals; the figures above are illustrative only.

Reviewing tests

Review tests on a calibrated display in a grading suite or a well-set-up review room, not on a laptop. Watch them with the director and, where possible, the colourist, production designer and costume designer. Make decisions on the spot and record them: lens set chosen, EI, filtration, LUT version, exposure targets and any changes for specific scenes. Share a short test report and selected stills with heads of department. The test report becomes part of the look book.

Documenting the pipeline

Before shooting, write a one-page pipeline document listing camera, firmware, recording format, resolution, frame rate, EI, white balance strategy, LUT names and versions, CDL workflow, monitoring setups, dailies format and delivery to editorial. Share it with the camera department, DIT, post supervisor, editor, dailies lab and colourist. Most pipeline problems on set come from someone using a different LUT or setting than everyone else; a clear document prevents that.