Arducam IMX219 autofocus blurry through ceramic glass on Raspberry Pi 4B

USB UVC Webcams
1

Hi everyone. I’m running an Arducam 4K 8MP IMX219 on a Raspberry Pi 4B, and the image saturation is really unstable. Sometimes the background comes out with a red blur instead of being clear. It works intermittently and feels very unstable overall.

2

That pattern sounds a lot like a lens shading problem rather than something in your capture logic. To confirm, I need to figure out which field of view (FOV) version of the camera you have. Could you send me your order number through a private message? I’ll use it to identify the exact variant.

3

I’ve tried changing the logic in my code and resetting the device a few times, but neither helped. I’ve just sent the order number over in a private message. Thanks for looking into it.

4

Thanks, I’ve received it and I’m checking the FOV from the order details. Right now the main suspect is still lens shading. When you see the red blur in the background, is it tied to any particular lighting or exposure settings, or does it seem totally random?

5

It seems pretty random, hard to tie it to one setting. I’d really like some suggestions to make the captures more consistent. Also, I’ve got a second problem now: the autofocus doesn’t work as intended when I capture an item through a glass pane. Without glass between the camera and the item, the image is clear. With glass in between, it’s blurry / not clear.

6

Those sound like two separate issues, let’s take them one at a time. For the glass problem - glass can definitely throw off autofocus, especially with reflections or coatings. Can you tell me what capture software you’re using and what kind of glass it is?

7

Sure. The camera is the Arducam 4K 8MP IMX219 (marked 4x B0292) on a Raspberry Pi 4B, and I’m capturing with OpenCV. The glass is Nextrema Ceramic Glass - I picked it for low thermal conductivity and good insulation at high temperatures. Ideally I want good visible light transparency and low glare, while keeping those thermal properties. Here are some samples:

8

Thanks for the images. The difference between the with-glass and without-glass shots makes it pretty clear the glass is interfering with focus - likely reflections or reduced contrast that’s making the autofocus hunt. Before I dig deeper on that, can you update me on the original red-background saturation issue? Is that still happening on your side?

9

The red-background issue actually got fixed after I swapped the camera for another unit. The autofocus through glass is still unresolved though. Are there any Arducam settings that can fix the autofocus in this situation, or is there a specific glass type you’d recommend for image clarity through glass?

10

Good to know the red-background problem cleared up after the swap - that points to it being a fault in the original unit. As for the current issue: the image is clear without the glass and soft with it, so the Nextrema ceramic glass is the main suspect for the autofocus trouble (reflections and lower contrast). We’re still looking into whether any camera settings can compensate for it, and whether a glass with better anti-reflective / visible-light properties would suit your thermal requirements. I don’t have a confirmed fix for the glass/autofocus part yet, but that’s the current conclusion.