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Raspberry no IR-filter camera see-through images

Sat Jun 22, 2019 5:37 pm

I have used Raspberry v[12] NoIR cameras only for capturing in the dark sofar, if not capturing at normal daylight.

In thread "ESP32-CAM ov2640 exposure control/FREX mode"
I try to bring ov2640 sensor into FREX mode as I did with Raspberry v1 camera (ov2640 sensor is a predecessor of v1 camera ov5647 sensor), in order to do global external shutter videos with ESP32-CAM module and ov2640 sensor.
According the ov2640 datasheet there are 38 pins on the sensor, and the cable provides 24 lines, 21 of those are connected.
Unlike ov5647 sensor that allows to enter FREX mode either via I2C command or via pin signalling, ov2640 only allows to enter FREX mode via pin signalling. The interesting pins for entering FREX mode are A2 (EXPST_B) and B2 (FREX).

So I wanted to see which 21 pins get exposed on the connector cable, and whether probably A2 and B2 are among them. First I did a 2MP v1 camera photo that gives quite some details for the sensor backside cable connections:

Unfortunately the other side of the connector cable is painted black and did not allow to inspect where the fore side connections of connector cable end. I remembered to have read somewhere that sometimes infrared light can "see-through" stuff. So I gave it a try, this time with a v2 NoIR camera, and a 12V 1A 48-led infrared light. I placed the connector cable slightly above ground in order to get IR light reflected from desk as well:

This is same scene with room completely dark, allowing the led light's photo resistor give full IR light, captured with smartphone camera:

I was impressed that it is now relatively easy to identify which fore side cable is connected to which of the 24 connector cable pins (right click and zoom 2MP photo to 100% display) -- this is "see-through" black image:

Another IR light see-through photo created after having removed metallic plate from other side of connector, and this time grey glue remained that did not allow to see through directly while working on the ESP32 thread: ... 338#p45338

This time connector with grey glue on top is just placed between v2 NoIR camera and 48-led IR light:

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