Do I need a 300mm?

Hello All. It’s freak’n hot here !

Anyhoo, so you know where I want to end up, I want to be able to just lay a 20oz tumbler down on the workspace. Click go, and run the job. I’m not getting a good engraving out on the sides on 3 letters or so. I’m using my 200mm lens, and using LB cylinder correction.

I’m pretty sure I’m focused cuz as I was running a test I raised and lowered my lens until I heard a small buzz. The widest sentence in the logo is 57.5mm… Well, well, within the boundary box in LB.

If I have to buy a 300 lens to do what I want, then so be it. Yep, I have a rotary, but it would be so much faster just to place, burn, pull, rinse and repeat.

What else should I be looking at if anything. I want to be able to do something like this around the 3:00 time marker.

You need to figure the curvature of the mug and the depth of field of the lens… F theta lenses are specific for Flat focus field.

You should adjust for the focus 1/2 around the curve or in the middle… Then the depth of field of the lens will range around the best focus point.

I bought my machine with a F420mm, covers 300mmx300mm… I also have an F100mm (70mmx70mm)… I refer to them as they are factory marked… that way I don’t have to guess…

Advantage of a long lens is the it has more depth of field… so it will reach around the objects curve further, while maintaining focus. There is also more room between the head and your work object.

How much it will help you, you’ll have to determine. You can find depth of field values, but you have to hunt for them… I keep my eye open and I rarely see these published…

Disadvantage is with a change to a longer lens, you speed/power values will change. I don’t know of any exact formula, but I use the ratio of the lens. For a 200 to a 300, I’d increase the power/speed for a 50% increase… as a starting point…

I still don’t follow why these change so much. I can double the lens length in my co2 with a lot less adjustment to the speed/power… to get the same results…

Good luck


Thanks Jack.

Looking at those video’s it looks really nice to be able to do it.

BUT, to be honest. When I had my rotary running these, it took me 5 seconds, to release the one done, and put another on.

I may just ditch the whole concept all together to be honest with you. I don’t think I’ll be gaining a whole heck of a lot in the long run anyway.

I’ve done several with my 110 and rotary, and have libraries already created with settings for them based on the color of the tumblers.

Hope your staying cool.

If you stay under 100W lenses, they are not that bad, price wise… I think the last one I got was about $60… for an F160mm…

Don’t know until you try, I guess …

Since you run Windows, I’d suggest you watch Laser Everything video on the CoreFile2 software that comes with the EZCad2 package. I think it’s much easier to setup a new lens with CoreFile2 software than the regular manual way… I do what’s necessary to not borrow the spouses Windows machine… I got EZCad2 to work on it and use it only for new lenses. 2 out of the four lenses I have were calibrated with CoreFile2…

Good luck