Downsides to Camera with 120 Degree Lens?

I’m looking into buying the LightBurn 8MP W camera. I have a 400x400mm work area. Is there a downside to getting the 120 degree version (eg effective resolution, focal depth, clarity)? Why would anyone get the 90 degree lens if the 120 is the same price and can be mounted lower?

The wider the angle, the more distortion in the camera image. This is not only more demanding computational wise (more CPU speed required) but also gives you less usable resolution.
You get best results with as few image distortion as possible. Then you have maximum usable resolution. Only use wide angle if you don’t have enough space above the laser.

So I would go for the 60° lens and even look for a 30° or less if you can mount such.

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Thank you for your response. The LB 8MP W camera only has 85 or 120 degree options. I haven’t built my enclosure yet, so mounting height isn’t an issue (within reason).
Do you know if the narrower lens has more focal depth (distance in which things stay in focus)? As I’m not planning to add an adjustable bed, more focal depth is better.

Yes, the narrower the lens, the more focal depth, usually. Though this is not only depended on the lens angle, it depends on the full optical stack.

You generally don’t get to choose where you mount the camera. It mounts on the highest point on the lid when opened, in the center. If you made a mount that stuck out 6" lower than the underside of the lid, the gantry would hit it when closed.

I got excellent results with a 16MP Arducam and this Varifocal lens. The Varifocal is not just focus, but it also sets the zoom level. So you can adjust it exactly to encompass the 4 corners of the bed and nothing extra, focus it, lock them both down, and get really good resolution.

The varifocal needs to be “1/3 inch sensor” to be able to cover the unusually large image sensor on the Arducam. If it’s a smaller one the light won’t project onto the entire imager, the resulting image will have the black walls of the tube in the image and you can’t change that.

https://www.aliexpress.com/item/1005001349942062.html?spm=a2g0o.order_list.order_list_main.17.fd0418023zaRH8&gatewayAdapt=4itemAdapt

Since the IR filter had to be removed with the original fixed lens, the varifocal needs its own IR filter as this one does.

You also need an M12 locking ring. The varifocal needs to be screwed in a specific spot somewhere mid-thread on the Arducam’s M12 female thread. It isn’t tightened down against the limit of either thread, so you need a floating M12 ring to tighten against the camera thread to lock it in place.

Danny I’m looking to add a targeting and monitoring camera to a Chinese 100W CO2 laser with 1000 x 600mm bed. It uses a Ruida 6445G controller. I note you mentioned Arducam. Which specific one did you use, and what sort of angular/linear field of view did this manage when coupled to the 1/3" zoom lens you mentioned?
Are there any downsides to your chosen combination, and would you pick anything different in the light of your experience with them?