Customizable Lens Diffuser for Macro Photography

This is a customizable diffuser that attaches to the end of a lens or microscope objective, using either filter threads or a friction fit. When lit from behind with sunlight, a flash or other light source, it provides a soft diffuse illumination for photographing small subjects. Many options are provided to customize the threads and the diffuser shape, and the end can be angled to provide better illumination coverage when the lens is positioned at an oblique angle.

Slicer Parameters

For simplicity you can just load the supplied print profile and replace the geometry with an STL generated by the customizer. If you want to set the parameters explicitly, here's what I recommend:

Quality

• Nozzle size: 0.4mm works well, but 0.2mm can give a thinner diffuser and more accurate threads
• Layer height: 0.08mm or as small as practical if printing threads; can be larger if not using threads
• Seam Position: Random (reduces warping in the diffuser cone)

Strength

• Wall loops: 1
• Detect Thin Walls: yes (otherwise parts of the wall may disappear if they're narrower than the minimum line width)
• Sparse infill density: 100%
• Sparse infill pattern: Concentric

Speed

• Reduce to about half of typical printing speed or layers may fail to adhere in the thin diffuser

Customization Tips

Threads

If printed filter threads are too tight or too loose, you can make minor adjustments using the Thread Adjustment parameters. With an adjustment of zero (the default), the threads are modeled at their actual (nominal) diameter, which normally would be too tight but material shrinkage tends to make them just a bit looser so with Bambu Matte PLA the default setting seems to work pretty well. But you may need to tweak the Thread Adjustment to get an acceptable fit. If the threads are just a bit tight, they will loosen up after attaching and removing a few times.

Definitely print the threads with a small layer height. A small nozzle may also improve the thread quality, especially if you need threads with a pitch much less than 0.75mm. I have printed 0.4mm threads using a 0.2mm nozzle and they came out pretty good, but it's hard to get the threads started properly on the lens because the pitch is so fine and the plastic is flexible.

Wall Thickness

I've had good luck printing these diffusers with a single wall loop in the thin diffuser part, and it gives fairly good translucency with white filament. The default wall thickness of 0.3mm will be thinner than the nominal line width with a 0.4mm nozzle, and the diffuser walls may disapper unless you have Detect Thin Walls enabled. If you use a smaller nozzle then you may need to reduce the wall thickness in the customizer to avoid getting 2 walls in some regions.

Curvature

The Curvature parameter lets you curve the diffuser walls outward (convex) or inward (concave).  A convex dome-shaped diffuser works well for most applications. A concave diffuser is trumpet-shaped, which may seem weird but it works well if illuminated from behind with a ring light because the trumpet shape gives a more uniform light distribution than a convex dome.