This August, Leica announced that they will no longer be able to repair the Leica M9 sensor. This sensor had an issue with corrosion or “sensor rot” that was caused by oxidation of the sensor glass. Sensors are typically built with a fused clear glass that covers the BGA grid and sensor microlenses. On top of this layer, there is usually 1 or two UV and IR cut filters to make sure the camera only sees visible light. This whole assembly adds some bulk though, and can cause corner sharpness losses when using film lenses. We offer a thin filter service to reduce this thickness in some digital cameras when people want the best performance with film lenses, particularly rangefinder lenses. Since this issue affects Leica lenses particularly, Leica chose a different design approach in their sensors to preserve their sharpness. Leica actually uses their UVIR cut filter and fuses this to the sensor directly. This allows them to achieve the very thinnest filter stack, but also makes repairs much harder. In most cameras if you scratch the front sensor, you can remove the scratched filter relatively easily (although it still requires a camera disassembly and skill, major companies still don’t do this repair locally). With the Leica sensors, a scratch or other damage meant that the whole assembly needed to be replaced. This became a particular issue when the M9 sensor glass started corroding across the board. UVIR cut glass is typically made with a Schott BG type material, which is chemically prone to oxidation. We saw this over a decade ago with our first hot mirror filters which are built with this same type of glass. Luckily, protective coatings on the glass can keep the material away from oxygen and prevent this issue, which is how we now treat our hot mirror filters. Schott has since developed oxidation resistant glass options, like the BG60 which we used in our V2 thin filter material. Leica unfortunately used an older S8612 glass, chosen for its high transmission at a thin thickness, and while this glass is coated, it failed to protect this glass sufficiently to prevent oxidation, causing corrosion issues across the board. If you lived in a humid area, you probably had issues quickly, but if you were in a drier area the issue may have taken several more years to appear. Leica initially offered a good will replacement for the corroded sensors between 2014 and 2017. After that, they charged $1,600 to replace the sensor, until stopping this August.
That’s where Kolari came in. We’re happy to announce that we can now repair the Leica M9 sensor and replace it with corrosion resistant glass for $999. We’ve removed Leica coverglass before, but haven’t looked into this repair earlier since there was a warranty option through Leica. We found out about this recent news after a few customers emailed us asking about the repair. So we picked up an M9 with a corroded sensor, and gave it a shot. We were able to delaminate the corroded filter from the sensor, and replace it with BG60 glass. This glass will last indefinitely without oxidizing per Schott test reports, and also allows us to reduce the Leica sensor stack by 0.2mm, further improving on it’s excellent corner sharpness. We can also replace the glass with our full spectrum glass making it IR and UV compatible.
BG60 vs the M9 S8612 Glass
The 0.6mm BG60 replacement glass we use has a very similar transmission profile compared to the M9 original, but it is slightly lower transmitting. This translates to a 1/4 stop light reduction overall.
If we apply an exposure correction to the BG60, you can see how similar the transmission profile is. There is a slightly higher UV sensitivity (lenses transmit little light under 375nm) while the IR side is virtually identical.
Note: At the moment, we only support the Leica M9. We do not have support for the Leica M Monochrome, Leica M9-P, M-E, or any other Leica camera other than the Leica M9. If you send in an unsupported camera, we will not attempt to repair it. We will notify you, send it back, and process a refund for your order minus any shipping costs and a 3-5% processing fee.
When working with corroded equipment, there’s a high degree of risk outside of our control when performing repair services. Most of the Leica M9’s we receive suffer from a heavily damaged ICF that may crack when being removed from the sensor assembly. We’re a highly skilled and capable repair shop but unfortunately, there isn’t much we can do to avoid this even under extreme care. If your sensor cracks during removal there is a chance that glass dust can land on the bare sensor which can cause fine scratches that can be visible under some shooting settings. Furthermore, we’ve been seeing that some M9’s are also affected by a liquid gel substance that can leak onto the sensor and also corrode through bond wires. This liquid gel is visible under a microscope but can’t always be seen. If we notice that your camera is affected by this substance we will reach out to you before we continue with your repair service and ask for permission to proceed. (We successfully repaired a few M9’s with corroded bond wires and the camera did not have any noticeable issues after being repaired but we can not guarantee this for every camera.) We can not be held liable for damages if the liquid gel spreads to your bare sensor during the repair service. We are also not liable for any liquid gel issues or electronic issues stemming from corroded bond wires after the repair service in the event that it is not visible during the repair. Lastly, some repairs are not possible (or very high risk) because of extremely strong bonding that can not be softened for a safe filter removal. If we find that we can not safely remove your ICF we will stop the repair process, reassemble your camera, notify you, and send it back. (This is the main reason we do not support the Leica M9M, M9-P, and M-E.)