Buying a 100w JPT Mopa E7, what lenses would you recommend?

Community Laser Talk
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I’m considering which type of lens I should buy. I’m thinking about using 110, 175, and 210 mm lenses, but I’m also considering dropping the 175 mm and just using the 110 and 210 mm lenses. However, I’m worried that this might have too much of an impact since I don’t really have much to compare it to.

My main applications would be deep engraving with the 110 mm lens, and more general surface engraving with the 210 mm lens—things like cleaning dirt off golf clubs or engraving magazines, where it’s mostly surface marking.

I’m wondering, how big is the actual difference between using a 175 mm versus a 210 mm lens for general engraving? Would it be noticeably worse if I skip the 175 mm and go straight to the 210 mm for those jobs?

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I don’t have a Mopa laser… but if I were to buy such a powerful laser I would definitely go for the largest possible lens. The investment in the “extra” lens is quickly forgotten and earned back and the possible application advantage will be permanently available to you.

PS. the difference between the two lenses you are talking about is 20% :wink: … and I would actually also go for a 300mm lens if it is available for the machine.

Just my subjective opinion

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If you need 100W then that’s great. The issue, as a hobbyist, was the cost. For my 60W MOPA, a regular lens is about $60, once I cross into the 100W and greater territory, my same focal length lens for 60W lens now costs about 8 times more at $480.

I have an F100mm, F160mm, F254mm and an F420mm lens for mine. The problem with an F100mm lens, is you can’t easily get into the small area with your hands and seeing it for focus is even worse. Of course, I wouldn’t be able to afford these lenses if mine were a 100W or more machine.

If you go from a longer lens to a shorter lens, the spot size is reduced. A 50% reduction in spot size relates to 1/4 the area or an apparent power increase of 4 times.

Most of the time I use my F254mm, lots of height so it’s easy to work with and keeps the lens away from the 175x175mm work area.

The difference between 100W and a 50W machine is the 100W pumps up the fiber twice as fast allowing more full power pulses/s. Of course you’re paying for it.

I’ve found 60W to be a nice power range. I can burn up objects, putting more power in, doesn’t necessarily give you a faster job…it could burn your material up real fast.

I’d suggest you get an F420mm (300x300mm coverage) as this will come with a tall column (mines 80cm). I actually use the F420mm quite often doing rocks. The taller column allows strange size rocks to be placed where they can be lased.

Mother nature doesn’t seem to make really flat rocks often enough, the extra 13mm of depth of focus using an F420mm is really handy for irregular sized rocks.

Even though @bernd.dk doesn’t have a MOPA, I think his insight is right on…

Good luck.

:smiley_cat:

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I’m thinking about buying a 300mm, 210mm, and 110mm lens.
It’ll be expensive, but it’s a “cry once, buy once” situation.

I’ll need to use a tower riser for the 300mm lens.
The only downside is that the focus point ends up quite high —
but it is what it is.
A tower riser will be necessary either way for a 300mm lens.

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Thank you, coming from a 30w fiber laser!