The phrase "focus down to" is correct and usable in written English.
This phrase is used to indicate that someone should narrow their focus to a specific topic or point. For example: "We need to focus down to the actual cause of the issue so that we can find a solution."
Conventional "aerodynamic lenses" utilize inertia to focus down to 25 nm in diameter (∼5 MDa); to date, Brownian diffusion has prevented the effective focusing of particles smaller than this.
The main selling point of the POV camera is that it can be held in the hand kind of like a pen and then can focus down to within 2.3 inches of an object.
But evolutionary thinking at the molecular level generally trails behind that at organismal levels, perhaps because few theorists and philosophers focus down to it.
She brought her focus down to his face and shakily explained, "Willy's away.
But the advantage of doing A-levels is that I'm keeping my options open, not narrowing my focus down to one profession.
It is a show which deploys such tight scrutiny of such tiny, unimportant things that it shrinks your focus down to just the shape of a model's mouth or the gap between her lips when she smiles.
Barreling ahead, straining at the curves, the group sounded wild but focused, down to the end of the line.
High-energy protons with 200 keV to 1 MeV can be focused down to 100 nm.
The second instrument is based on Fresnel zone plate optics focusing down to 10 nm.
The A−X transition is experimentally found to be saturated at a laser fluence of 1.5 mJ/pulse focused down to a beam waist of 3 mm.
Liu et al. carried the time scale of time-reversed ultrasonically encoded (TRUE) optical focusing down to a few milliseconds [23].
