Bed size vs Camera angle lens options

[vobuse (Kirk Hickling)]

About to purchase the camera option from Lightburn for my Redsail M900 which has a 900x600 working area.
What is the best option for this bed size based on the variants of camera angle lens available. Ultimately, my objective is to improve the workflow with full camera coverage (900mmx600mm).

I await the advice, thanks in advance.

Kind Regards.

[Blake (Blake Bartlett)]

An important piece of information is the distance from your open lid mounting spot to the bed.

[Chris (Chris Leitch)]

This is a frequently asked question

What is the best camera lens to choose for my bed size?

To answer this question requires one additional piece of information: The height above the bed that you plan to mount the camera. LightBurn now has a helper that will do the ugly math for you. Go to Help > Camera Selection Help and the software will use the current workspace size by default, and show you the minimum mounting heights for all the cameras we sell: [image] This number is the absolute minimum required for the camera to see the whole working area. You will need to allow a little …

[vobuse (Kirk Hickling)]

Tell me if I am on the correct path here

My bed size is 900x600.

I measured from bed to cover which came in between 35 to 36 inches. When converted to mm this comes to 889mm and based on your formula:
900/1.4 = 635 which no where close to 889mm
900/0.825 = 1077.57 which is closer to 889mm hence 60 degree angle lens is the best fit

[Chris (Chris Leitch)]

The calculation is for the minimum distance.

If you try the 60 degree lens you’ll end up cutting off part of your bed.

You’d be better with the 90 degree lens based on your calculations.

[LightBurn (Oz)]

Chris is spot on - The number is the minimum height above the bed for the camera to see the entire area. So the 60 degree camera would need to be mounted 1077mm or higher to see the whole bed. The 90 degree camera would be 635mm or higher. At 890mm you’re only about 145mm above the minimum spot, which won’t affect much - just means you have a little wiggle room, which is a good thing.

I won’t have 90’s in stock for a couple more weeks because of the Chinese New Year holiday. I’ll announce on the forum when we get our next batch in.

[vobuse (Kirk Hickling)]

Ok duly noted.
Please expedite the order as I have some big jobs coming up in short order, thanks.

[woodini (Giovanni Di Costanzo)]

my bed size is 1400 mm x 700, so with 160 degree I would have to have 1,400: 2.7 = 518 mm minimum height from the bed to check the whole area?

[LightBurn (Oz)]

Your math looks right, yes.

If you’re going for “basic alignment” that should work, but if you want good accuracy on the sides with a bed of that size, I’d suggest going with a 120 degree lens to minimize the distortion. A 160 degree lens means that the sides have significantly less resolution to work with.

An illustration of why that is:

Camera help if you will

It is better to use a narrower lens if you have the option, yes. Have a look at this graphic: [CameraBandSpread] Each of the bands here is the same number of degrees wide, but they vary dramatically in width where they hit the imaginary bed at the bottom. This means that the middle area of the image has more camera pixels per mm than the edges do, and the wider the lens, the worse this gets, which is why really extreme fisheye lenses squeeze the image together around the outside edge. This…

The view from a 160, 140, and 120 over a 700x500mm bed:

Camera distance

For the red/black, the 140 seems like a good choice for lid mount. It’s got enough extra room to allow some flexibility. For the red/black 700mm x 500mm, here are the images from 3 different cameras mounted in the lid: 160 degree: [View-160] . 140 degree: [View-140] . and 120 degree (note this is fuzzy because I didn’t take the sticker off the lens): [View-120] . The 120 cuts it pretty close, while the 160 captures too much extra around the bed.