Problem with down looking camera lighting

[svetozar161]

Hello. Following the example of the respected Mike Menci, I bought a Keyence CA-DXW3 light on AliExpress. I installed it according to his diagrams and connected it to 12 volts. And this is what I received, you can clearly see in the photo: a very bright spot of light. The height from the lens to the circuit board is about 90 mm. The camera has an 8 mm lens. Why is this spot formed and the image is somehow blurry? Is the light very bright? Mike's pictured product is perfect; it's the same light. Can anyone help?

[svetozar161]

https://drive.google.com/file/d/1GIkZx6vT9zbRgyX4RRkNDFCF-Y2iGGir/view?usp=sharing, 

https://drive.google.com/file/d/1XYUlneF6emklQA3bG7PB_LSfDrSZ-xxQ/view?usp=sharing, 

https://drive.google.com/file/d/1aJCStBquNRH_HgUtsLccozMyPwkAptDS/view?usp=sharing,

https://drive.google.com/file/d/1c6xCcC52I-d6nVUCvsWfWANdwYLls2Q5/view?usp=sharing

вторник, 26 мая 2026 г. в 23:30:22 UTC+3, svetozar161:

[Luke Bayes]

I can't speak for the original author, or this device, but it looks like you could use a polarizing filter.

Dave at eevblog did a great job explaining how they work for PCB systems like these.

Best,

lb.

--
You received this message because you are subscribed to the Google Groups "OpenPnP" group.
To unsubscribe from this group and stop receiving emails from it, send an email to openpnp+u...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/openpnp/82c2d6fe-bc48-4219-8cf5-61842e88f09dn%40googlegroups.com.

[Mike Menci]

Reduce the Highlight - and adjust the focus or change the camera lens - move camera closer to PCB... you need to find the right settings with OpenPnP I&S - which camera are you using =??  

[Селенин Алексей]

Hello Mike. Thank you for your attention to me. The camera is using ELP FHD 5 mpx with IR lens 8 mm. The coaxial light consumes only 90 mA with 12v. How can I reduce the brightness? Using the current regulator? If I lower the camera, I can't adjust the focus. Which lens should I use? 3.6mm? 6mm?

ср, 27 мая 2026 г. в 07:50, Mike Menci <mike....@gmail.com>:

To view this discussion visit https://groups.google.com/d/msgid/openpnp/167188e8-dab6-4625-ba82-9957fb8211acn%40googlegroups.com.

[Mike Menci]

Try 6mm focus and no IR - yes reduce voltage to less than 12V - visualy see which voltage will do the equal light on PCB.-... test needed...

[Mike Menci]

One more note - Down looking camera is not as important as up Looking camera for Vision in OpenPnP - might be more useful to use your Coax setup for Up looking camera??

On Wednesday, 27 May 2026 at 09:16:21 UTC+2 sveto...@gmail.com wrote:

[Селенин Алексей]

Thanks, Mike, I'll try. It's just that the smaller the lens, the greater the fisheye distortion. I'll try and write a report.

ср, 27 мая 2026 г., 10:38 Mike Menci <mike....@gmail.com>:

To view this discussion visit https://groups.google.com/d/msgid/openpnp/054d6525-4c14-421f-a4e2-236dd9701feen%40googlegroups.com.

[Mike Menci]

See this !

[Селенин Алексей]

I understand, I will deal with it later. Now I'm redesigning the machine again. As much as possible, I'm moving away from inaccurate printed plastic parts and switching to aluminum CNC parts. This will be the second version of the machine. I'll deal with the up-looking camera later)) However, it seems that there were no issues with it in the first version of the machine.

ср, 27 мая 2026 г. в 10:45, Mike Menci <mike....@gmail.com>:

To view this discussion visit https://groups.google.com/d/msgid/openpnp/2c279c9e-110f-43f3-92b0-f63a7d941293n%40googlegroups.com.

[svetozar161]

I bought five different M12 lenses: 3.2mm, 3.6mm, 6mm, 8mm, 12mm, and I'm trying to figure out which one will work. The smallest lens, 3.2mm, has a very strong fisheye effect.

среда, 27 мая 2026 г. в 10:55:58 UTC+3, svetozar161:

[Andreas Petter]

I can strongly recommend using Claude or any other strong AI to understand your camera and optics. I had a similar problem with optics and I got a great result from it. The right distance for a given lens, the right angel of view and expected focus depth, wich depends a lot from light and aperture. 

Finally I chose 6mm for down looking and 16mm for upwards. The angel of view is around 15x23 mm which is small but gives good precision and large enough to capture all packages and fiducials. 

Furthermore, I would recommend using a monochrome camera with global shutter. This is by far the most precise option.

[John B]

It also looks like your down looking camera is auto exposure adjusting, trying to get the high lighter area to be properly exposed, and it can't quite make it. The area of the board that is not a direct reflection is showing quite a bit of noise in the image, as it is not getting nearly enough light. Also, due to the great intensity of the light, either there is a lot of internal reflection in your camera lens and or it is dirty.

Any light source that can reflect of the shiny surface of the PCB and other components and directly towards the lens is going to produce glare/hot spots. The first thing I would do, is un mount the light source (but it should remain on) and move it around , while looking at the image from the down looking camera, you should see the hot spot move around. The point where it is least problematic, is where you should mount the light source.