First, let me note that I am not offering precise quantification of the magnitude of the effect we are discussing; after all, the data id not for any of the Canon, Sony or Nikon (CMOS or ILT CCD) sensors that the original article is dealing with; just with what seems an clear fact, that microlenses cause a significant fall-off in sensitivity as light comes from an off-perpendicular angle, including the light form the outer parts of there light cone from a low f-stop lens (like f/1.2 and maybe f/1.4) even at the center of the frame. But for reasons I have stated before and restate below, it is likely if anything to be greater with current DSLR front-illuminated active pixel CMOS sensors than with Kodak's FF CCDs.
Second, even if one denies that microlenses are the cause, the effect
is still there in every single microlenses sensor I have data for (four different FF CCDs of three different pixel spitches from Kodak.)
... On second reading it could also mean (and would be more likely) that there is a row of shielded pixels around the entire array of photosensitive sensels.
The second reading is correct: this is a border around the edge of the entire sensor, not within each photosite. This is made clear in the early pages of the long spec document for the KAF-39000, and in every Kodak FF CCD long spec: see http://www.kodak.com:80/global/en/business/ISS/Products/Fullframe/
Despite the identical 6.8 micron sensel pitch, the datasheets mention different sizes for the sensor array, ... They also mention different numbers of pixels, confusing ...
It is not at all confusing if you read a bit more carefully: these are sensors using the same basic 6.8 micron photosite design but of different sizes (44x33mm vs 49x37mm) and thus of different pixel counts (39MP vs 31MP). But that difference is irrelevant to per pixel performance characteristics.
All I'm saying is that differences in design make comparisons difficult, and certainly not a basis to generalize on, and the (also mentioned in the datasheet, offset) microlenses were instrumental in increasing the overall sensitivity of the (more special ?) design.
I would rather draw general conclusions about microlenses based on identical sensor array designs, only differing in the use of microlenses or not, that's all. That will probably be data that's hard to find.
The difference in overall sensor size and pixel count is irrelevant to the question we are discussing: we are looking at what happens at an individual photosite, anywhere on the sensor, when light strikes it at various angles, and Kodak gives data for those two contemporary sensor designs for what happens at a photosite at the center of the sensor. By the way, here is another earlier one with microlenses but not offset, that KAF-8300 of the Olympus E-300 and E500: http://www.kodak.com:80/global/plugins/acrobat/en/business/ISS/datasheet/fullframe/KAF-8300LongSpec.pdf
and the KAF-18000, an 18MP, 44x33mm sensor with 9 micron pixels and non-offset microlenses:http://www.kodak.com:80/global/plugins/acrobat/en/business/ISS/datasheet/fullframe/KAF-18000LongSpec.pdf
which you might want to copare to the same generatio 22MP, 49x37mm KAF-22000 with no microlenses and far less off-perpendicular fall-off:http://www.kodak.com/global/plugins/acrobat/en/business/ISS/datasheet/fullframe/KAF-22000LongSpec.pdf
The angular fall-off is even worse for the older KAF-5101 of the Olympus E-1, with 6.8 micron pixel pitch and non-offset microlenses, but that is no longer at Kodak's site.
It becomes hard to conclude anything that than, consistently over eight years of putting microlenses on FF CCDs, Kodak has been forced to sacrifice off-perpendicular sensitivity fall-off as part of the price of adding microlenses.
The size difference is however relevant in a different sense: despite the substantial advantages in QE that microlenses give when Kodak uses them in FF sensors (about doubling QE and thus adding one stop of sensitivity) and despite Kodak having had this technology since the KAF-5101 from 2002 with this same 6.8 micron pixel spacing, Kodak has never used microlenses on its larger MF sensors, the ones about 49x37mm, while using them on three generations of its smaller 44x33mm FF CCDs for MF (KAF-18000, KAF-31600, KAF-40000). The reason seems obvious, especially since Kodak more or less states it in text I have already quoted: adding microlenses has the unfortunate side-effect of causing greater fall-off in sensitivity to off-perpendicular incident light, causing a kind of vignetting, and this increases as distance from the center of the frame increases. The effect is thus more tolerable with the smaller radius (corner distance) of the 44x33mm MF sensors than with the larger radius of the 49x37mm sensors. Before Kodak had off-set microlenses, it did not use microlenses on any MF sensor.
I ask again: can anyone suggest any plausible reason why Kodak would hamper every one of its microlensed FF CCD sensors in this way if it could combine the QE advantages of microlenses with the greater off-perpendicular sensitivity that all its non micro-lensed FF CCD sensors have, going back many years?
Or to put it another way, why does Kodak continue to hamper the sensitivity of all its largest 49x37mm MF sensors with substantially lower QE by not offering any of them with microlenses, except due to its inability to add microlenses while avoiding the vignetting problem due to sensitivity that declines too fast as the angle of incidence increases?
And to the idea that this is just inability on Kodak's part, I will note again that (a) Dalsa says the same thing about off-perpendicular sensitivity fall-off being a disadvantage of microlenses, and (b) as Dalsa explains, the problem is likely to be worse with all recent DSLR sensors because they are all front-illuminated CMOS sensors, and thus microlenses need to be further from the wells.