Metering Cell Emulated Board for Leica CL Camera [V6 - Production Batch]

Leica CL Metering Cell Replacement

A drop-in metering cell replacement for the Leica CL camera. It was noted that metering calibration is necessary, and the installation requires soldering. For professionals only, no technical support is provided. 

Information only - use at your own risk.

The calibration step typically requires three tools:

1. A 1.35-volt constant power source. Available at our web store.
https://polarbearcamera.com/products/usb-c-to-1-35v-high-precision-dc-dc-converter-exposure-meter-calibration

2. A light box (constant lighting source)
3. Metering reference (phone app or a working camera)

Installation stage:
1. Use a pair of tweezers to remove the cell enclosure cover.
2. Desoldering and removing the original metering cell.
3. Secure the new metering cell to the cell enclosure. Double-sided tape or solvent-free glue is recommended.
4. Soldering the new metering cell.
5. Install the enclosure cover. 

Calibration Stage:
1. Choose a constant light source that is brighter than the room's current condition.
2. Add a lens to the target camera.
3. Set the lens to its widest aperture and the target camera's ASA to 100.
4. Use any metering app on your phone or another camera (the reference camera) to achieve the same aperture and ISO settings.
5. Compare the readings from the target camera and the metering reference source.
6. Adjust the target camera's variable resistors.
7. Repeat steps 3–6 with the lens set to its smallest aperture setting to perform low-light environment calibration.
8. Repeat steps 3–6 with different aperture settings to ensure metering linearity is maintained.

Reference videos:
https://www.youtube.com/watch?v=hyhpoPGTuag
https://www.youtube.com/watch?v=vNrW80Q1bPs

Reference article:
https://www.fredmiranda.com/forum/topic/1939477/0

Revision History

• January 2025:
  • Production version released (V6).
  • Improved temperature control during the SMT reflow process, which peaked at 180°C.
• December 2024:
  • SMT manufacturing difficulties delayed the release, damaging the LDR components during the high-temperature reflow process.     
• October 2024:
  Production batch (V4) will be available in early December 2024 Jan 2025, with the following improvements:
  • Improved linearity of light response versus resistance change
  • Improved metering accuracy in low-light environment 
• February 2024:
  All V3 engineering samples are out of stock. We are waiting for feedback from Leica specialists and customers.
• November 2023:
  Engineering Sample V3 Released:
  • Closer and more centred cell placements will reduce vignetting at small apertures. Maximising light exposure.
  • Low-temperature hand soldering is used to preserve LDR lifespan.
  • Tinned soldering pad for effortless installation.
• September 2023:
  Engineering Sample V2 Released:
  
  • Removed adjustable resistor.
  • Added light-dependent resistor (LDR). Total LDRs = 3.
• June 2023:
  Engineering Sample V1 Released:
  • First prototype released for public testing.

*No technical support is provided with this item.