Missed that x3.
Vari-power is immensely tough to make work on photographs. It’s not really my style for engraving - I like the printed on look typically.
Material only holds so many shades of burn. When you use vari-power to engrave a photo, you’re basically reducing the image to a X-color GIF (say 6-color GIF). And then the edit and power settings need to be perfect in that the grayscale values need to be hitting those different speed/power/LPI sweet spots (to get the different shades) just right.
The more successful 3D photo engravings I’ve seen tend to be edited to be “comic-like” in that they have very exaggerated features. In Photoshop, you’d probably want to look at things like the emboss filter (and then additional editing) to accomplish that.
As for convert to dots, which is really dithering. It uses just on or off to produce dots. The lighter the value, the further the dots are; the darker the value, the tighter the dots are. Our brain perceives those as shades. You can hit a lot more perceived shades with dithering than you can vari-power.
In the end though, you can hit some really photo-realistic engraves with a laser.