I'm trying to create this halftone effect in Inkscape but I'm not able to produce it. All I'm able to do is create a small circle and clone it to produce simple halftone. But how do I do this?
To quickly create the desired image we can use the Clone > Create Tiled Clones... tool.
Here is the steps involved (in Symmetry: P1: simple translation mode):
By choosing different settings we may change number or color of dots, rotation, or introduce a fade effect if needed.
You can create rings of dots by using a rotation transform. Offset the center of rotation of a dot, duplicate it, and apply a Rotation Transform. The angle of rotation will be defined by the number of desired dots in the circle divided by 360.
You can use the same technique to quickly create multiple rings. This is not quite exactly the same as your posted graphic because it will result in the same number of dots per ring, but this will help illustrate how to use transform and duplicate together:
Start with a ring like this, select it:
Duplicate it via Edit → Duplicate or by pressing Ctrl + D
Apply a Scale Transform via Object → Transform
Repeat until happy: