IMX299CJK in GH5S Back-Illuminated or Front-Illuminated

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JakeJY Veteran Member • Posts: 5,314
IMX299CJK in GH5S Back-Illuminated or Front-Illuminated

I see in another thread there there was an argument over whether the IMX299CJK in the GH5S is back-illuminated (BI or BSI) or front-illuminated (FI or FSI). Don't want this to turn into an emotionally charged debate, but just wanted to discuss this from a factual standpoint, as the truth does make a significant difference in how to analyze different results (related to advantages of BI vs FI sensors).

I always presumed the IMX299 was BI due to most of the evidence pointing that way, but if it's a FI variant of the IMX294, that would be a fairly interesting difference.

Some links first. Tech Insights confirms the sensor in the GH5S sensor is the IMX299CJK.

Some of this may be settled easily if someone spends the money on that report, but I doubt anyone wants to do that just to settle curiosity (although if you have a corporate email, you may be able to look at the table of contents or a sample report as a guest to look for clues to the answer).

Arguments for it being a BI sensor:

Sony's website claims in the table of sensors that IMX299 is a BI sensor, as do various distributors that sell the sensor:

The specs are nigh identical to the IMX294, which the spec sheet does explicitly say is a BI sensor, although due to Sony switching units (and perhaps even test methods) when mentioning sensitivity, those can't be cross referenced. The IMX294 was what a lot of people though the GH5S was using.

Arguments for it not being a BI sensor:
Panasonic never claims GH5S has a BI sensor, nor does Blackmagic on the BMPCC 4K, nor does ZCAM on the E2.

The spec sheet for IMX299 does not explicitly say it is a BI sensor:

However, I wasn't able to find a reference of those camera makers saying that the sensor is FI either or sensor vendors saying the IMX299 was FI.

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