Why are FOV different between H7_R1 & H7_R2?

OpenMV Products
1

Hi everyone,

I have recently bought a Cam H7 R1 and a Cam H7 R2. I have then put a wide lens on both boards. But I noticed than the Field Of View is reduced on the R2 compared with the R1.
I use the Cam to decode datamatrix on some labels. You can see on the screenshots attached that, for the exact same code running on both boards, the image is zoomed with the R2 (I have hidden some writings for privacy concerns, but you can look at the datamatrix). The image is set as follow : sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.VGA) #VGA : 640x480
sensor.set_windowing(0, 120, 640, 240)

I know that the R2 comes with a best image sensor than the R1, but I did not think it would impact the FOV or the zoom.

So my questions are:

  1. Is this difference of view normal?
  2. If this is normal, how could I have anticipated it from the R2 documentation or from the sensor datasheet? Is there a specific parameter for this?
  3. Is there a way to correct this so that the image look as the one from R1?

Thanks in advance, and for the hard work concerning the OpenMV products!

Montage
Montage801×611 222 KB

2

Hi, it’s because the image sensor is smaller. We tried to find a compatible lens but our first production of them was a little rushed and the lens was off. If you use the wide angle lens you will get a similar field of view.

The cameras chips are physically different in size though which causes this affect.

3

Hi, thanks for having replied so quickly!
I did not know the sensor size could reduce the field of view.
To be sure I understand well: on R2, the wide angle lens gives the same field of view than the normal lens? And a “compatible” lens could compensate this size difference so that we could have a larger FOV?

4

Yeah, by increasing the FoV on a lens you’ll get back to more normal behavior.

5

So, to be sure, are you telling me that I should use a lens with even more FoV than the wide angle lens to get the same FoV than R1?

6

… yes …

7

Alright, thanks!

I was doubting because, when I read “If you use the wide angle lens you will get a similar field of view.” in your first message, I wondered if you meant that the FoV would be unchanged even with an increased FoV from an even wider lens.

Do you have an idea of when you will find a compatible lens for this sensor?

8

Our wide angle lens or something with similar specs will do.