LC Apollo User Manual

LC Apollo will be available for pre-order shortly.

1. Introduction to Apollo

Light Counter Apollo is an exposure meter designed for historical and alternative photographic processes. Unlike a conventional light meter, Apollo measures ultraviolet, visible and near-infrared light in ten wavelength bands. A selectable process recipe tells Apollo how strongly each band affects your photographic material.

This makes Apollo particularly useful for processes such as wet-plate collodion and historical gelatin dry plates, whose response to light is very different from that of the human eye. Apollo combines the measured bands using the selected recipe, applies the recipe's Exposure Index (EI), and recommends an aperture and exposure time.

Apollo is a practical exposure tool rather than a laboratory instrument. Historical-process speed varies with chemistry, material preparation, age, development, lens transmission and illumination. Treat the supplied recipes as starting points and refine them with test exposures made using your own equipment and working method. 

Moving between screens

Swipe left or right across the display to move through Apollo's main screens: Home → Process Recipes → Sensor Calibration → Shutter Speed Test → System Information. Swipe right from the Home screen to open Settings. Swipe left from Settings to return Home.

2. Home screen


The Home screen is Apollo's live meter and exposure timer. Point Apollo at your subject to get a meter reading. The sensor as an approximate 40º field of view.

What the display means

  • Aperture — the selected working aperture. Drag upward or downward on the aperture panel to change it. Apollo recalculates the exposure time immediately. The available steps follow the Aperture Increment selected in Settings.
  • Exposure time — the recommended shutter time for the displayed aperture. This includes any active exposure adjustment and, when enabled, reciprocity correction. During a timed exposure, this panel shows the remaining time.
  • LOW LIGHT — the calculated exposure is beyond Apollo's normal displayed working range (up to 24 hours exposure)
  • TOO SHORT — the calculated exposure is shorter than Apollo's normal displayed working range (less than 1/5000)
  • XV — Apollo's process-weighted light value. It describes the effective light reaching the selected process after the recipe's wavelength weights have been applied. It is conceptually similar to a conventional Light Value (LV), but is specific to the selected recipe.
  • EV — the Exposure Value after Apollo applies the selected recipe's EI to the XV reading. EV is used with the chosen aperture to calculate the recommended exposure time.
  • Spectral chart — ten coloured bars show the relative amount of light measured in Apollo's ten wavelength bands. The solid part of each bar shows the proportion used by the selected recipe; the pale remainder shows light that was measured but reduced or excluded by that recipe. Bar heights are relative to the strongest currently measured band, so the chart is intended to show spectral balance rather than an absolute irradiance scale.

Apollo's wavelength bands

Band Approximate Wavelength
Ultraviolet 360 nm
Violet 415 nm
Blue 445 nm
Blue-Green 480 nm
Green 515 nm
Yellow-Green 555 nm
Amber 590 nm
Red 630 nm
Deep Red 680 nm
Near-Infrared 910 nm

Home-screen controls

  • Adjustment button — enter a signed exposure adjustment in stops, to one decimal place. A positive value lengthens the exposure; a negative value shortens it. The button is highlighted whenever a non-zero adjustment is active. Enter zero to clear it.
  • Reciprocity button — turns reciprocity correction on or off. The button is highlighted while correction is enabled. Apollo uses the reciprocity factor stored in the selected recipe and applies it only when the uncorrected exposure is at least one second.
  • Stopwatch button — starts the exposure-timing sequence. Apollo first asks for confirmation. Confirm to begin or cancel to return to live metering.
  • Pause/Resume — while the timer is running, use the pause button to stop the countdown temporarily and the resume button to continue.
  • Stop/Cancel — cancels an exposure that is in progress.

When an exposure starts, Apollo freezes the selected aperture and uses a light integrator function to adjust the exposure time to allow for changing light conditions. Sound cues follow the Metronome and Countdown Beeps choices in Settings.

Process recipes

A recipe describes the response of a particular photographic material or working process. It contains a name, EI, reciprocity factor and a weight from 0% to 100% for each wavelength band.

The weights do not need to add up to 100%. They form a response curve, for example 100% uses the band fully; 50% gives the band half influence; and 0% excludes the band from the exposure calculation.

Use EI to adjust the overall exposure. Change individual band weights only when the recipe performs differently under light sources with different spectral character.

3. Process Recipes screen

Swipe left from Home to open Process Recipes. Apollo provides six recipe slots. Touch a recipe name to select it; the highlighted row is the recipe currently used by the Home screen. Your selection is saved automatically.

To edit a recipe, select it and touch the pencil button. Swipe right to return Home or left to continue to Sensor Calibration.

Factory-default recipes

The first three slots contain starting points for historical blue- and ultraviolet-sensitive processes. The remaining three slots are generic editable recipes.

 Recipe Initial EI Reciprocity Factor 360 415 445 480 515 555 590 630 680 910
Wet Collodion 2 1.50 100% 90% 45% 10% 0% 0% 0% 0% 0% 0%
Early Collodion 1.2 1.50 100% 75% 5% 0% 0% 0% 0% 0% 0% 0%
Dry Plate 4 1.50 100% 100% 70% 10% 0% 0% 0% 0% 0% 0%
Recipe 04-06 100 1.50 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%

Wet Collodion represents a mature wet-plate formula containing bromide and iodide. It has strong ultraviolet and violet response, declining blue response and a small contribution near 480 nm.

Early Collodion represents the predominantly silver-iodide collodion used during the early years of the process. Its response is concentrated in ultraviolet and violet light and falls sharply around 440 nm.

Dry Plate represents an unsensitized silver-bromide gelatin dry plate, with strong ultraviolet, violet and blue response. It does not represent later orthochromatic or panchromatic plates.

The factory EIs are practical Apollo starting points and may differ from an EI quoted for use with a conventional meter. Apollo excludes wavelengths that do not expose the selected material, while a conventional meter may still count them as visible light. Make bracketed tests and tune EI for your own formula, lens and development.

Factory defaults are installed on a new unit and restored by a full factory reset. A firmware update does not overwrite recipes you have already saved.

4. Editing a recipe

The Edit Process Recipe screen changes the selected recipe.

  • Recipe name — touch the name to edit it. Names can contain up to 16 characters. The name is for identification and does not affect exposure.
  • EI — touch the EI row to enter the effective working speed, with one decimal place. A higher EI gives a shorter exposure; a lower EI gives a longer exposure. Doubling EI shortens the exposure by one stop.
  • Reciprocity factor — touch this row to enter a factor from 1.00 to 9.99. Apollo uses the factor only when reciprocity is enabled on the Home screen and the uncorrected exposure is at least one second. The calculation is `corrected time = metered time ^ reciprocity factor`. A factor of 1.00 makes no change; factors above 1.00 lengthen exposures progressively.
  • Band chart — touch a coloured band to enter its weight from 0% to 100%. The bands run from left to right in the same order as the wavelength table: 360, 415, 445, 480, 515, 555, 590, 630, 680 and 910 nm.
  • Trash button — resets this one slot to a generic recipe: its numbered name, EI 100, reciprocity factor 1.50 and all band weights at 100%. It does not restore the original Wet Collodion, Early Collodion or Dry Plate preset.
  • Cross button — leaves the editing screen without explicitly saving to flash.
  • Tick button — saves the recipe and returns to the Process Recipes screen.

For best results, adjust the spectral weights to match your film/plate technology, then adjust the EI to set a suitable speed for your process. Test with real-world conditions to confirm the recipe. Test long exposures separately before changing the reciprocity factor.

5. Sensor Calibration

Sensor Calibration aligns Apollo's exposure reading with a trusted reflected-light meter.

  1. se a white wall in open shade, with even illumination and no direct sunlight or strong reflections.
  2. Set a trusted reflected-light meter to EI 100 and meter the wall.
  3. On Apollo, drag the Aperture and Shutter controls upward or downward until they match the reference meter's reading.
  4. Point Apollo at the same area of the wall.
  5. Touch the Calibratebutton.
  6. Keep both the target and Apollo steady while Apollo takes and averages its measurements.
  7. Wait for Calibration complete. The new calibration factors are saved automatically.

If calibration fails, check the setup and try again. Swiping left or right while calibration is running cancels it. Swipe right to return to Process Recipes or left to open Shutter Speed Test.

Calibration changes Apollo's stored sensor factors. It does not change an individual process recipe. Because a factory reset restores the original calibration factors, recalibrate after performing a factory reset.

6. Shutter Speed Test

The Shutter Speed Test measures the duration for which a camera shutter allows light to reach Apollo.

  1. Point the camera lens at a bright, steady light.
  2. Place Apollo behind the lens, where the film or plate would normally receive the image.
  3. Touch the aperture/shutter-test button.
  4. Keep the camera and Apollo still while Apollo measures the ambient baseline.
  5. Wait until Apollo displays Ready and sounds a short cue.
  6. Fire the camera shutter. Apollo starts timing when the light rises and stops automatically when it falls.

Apollo displays the measured duration and, for times below one second, the nearest equivalent reciprocal shutter speed. Touch the button to repeat the test.

The expected accuracy is approximately ±1 ms for shutter times from 2 ms (1/500 s) to 10 seconds. A detected pulse below 2 ms is reported as faster than 1/500 s rather than as a precise measurement. If the test times out, improve the contrast between shutter-closed and shutter-open light, check alignment, and try again.

Leaving the screen stops the test and returns Apollo's spectral sensor to normal metering. Swipe right for Sensor Calibration or left for System Information.

7. System Information

The System Information screen shows:

  • The product model
  • Apollo's serial number
  • The installed firmware version and build
  • A QR code linking to the online user manual.

Firmware upgrade

Touch the firmware button to view the upgrade instructions. Connect Apollo to a computer with USB-C, then touch the tick to confirm. Apollo restarts as an external USB drive. Copy the supplied Apollo `.uf2` firmware file onto that drive; Apollo installs it and restarts automatically.

You may cancel with the cross before confirming. Do not copy firmware intended for another Light Counter model.

Factory reset

Touch the trash button, then the tick, to reset all settings and peripheral configurations. This cannot be undone. The reset restores the factory process recipes and calibration values, then restarts Apollo. Touch the cross to cancel.

Swipe right to return to Shutter Speed Test.

8. Settings

Swipe right from Home to open Settings. The three numbered buttons select the Exposures, Display and Sound pages. The highlighted button shows the current page. Swipe left when finished; Apollo saves the settings and returns Home.

Settings: Exposures

  • Default Aperture — the aperture shown when Apollo starts. Drag upward or downward on the value to change it. The factory default is f/8.
  • Aperture Increment — chooses Full, Half or Third-stop aperture steps for the Home screen. Third stops are the factory default.

Settings: Display

  • Display Mode — selects Light, Dark or Red. Light provides a pale background, Dark uses a dark interface, and Red limits the interface to red tones for use when working with orthochromatic materials.
  • Display Brightness — selects level 1 through 5. The change is applied immediately.

Settings: Sound

  • Volume — selects Off, Quiet or Loud for Apollo's buzzer. Quiet and Loud play a short sample when selected.
  • Metronome — sounds a regular timing cue during a running exposure. Choose Off or an interval of 1, 5, 10, 30 or 60 seconds.
  • Countdown Beeps — enables countdown cues near the end of a timed exposure. Choose Off or begin the countdown at 5, 10, 15, 20 or 30 seconds remaining.
The Metronome and Countdown Beeps are independent. For example, Apollo can give a cue every 10 seconds throughout a long exposure and then provide countdown cues during the final 5 seconds.