JakeJY
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Veteran Member
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Posts: 5,314
IMX299CJK in GH5S Back-Illuminated or Front-Illuminated
4 months ago
2
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.
https://www.techinsights.com/products/def-1802-802
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:
https://www.sony-semicon.co.jp/e/products/IS/camera/product.html
https://www.macnica-atd-europe.com/product-page/sony-imx299cjk-c
https://www.gophotonics.com/products/cmos-image-sensors/sony-corporation/21-209-imx299cjk
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.
https://www.sony-semicon.co.jp/products/common/pdf/IMX294CJK_Flyer.pdf
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:
https://www.sony-semicon.co.jp/products/common/pdf/IMX299CJK_Flyer.pdf
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.