Place a reflective syringe or similar cylinder in a V-block over a backlight, then repeat the view with a ring light and with bar lights parallel and perpendicular to the barrel. The part is a useful bad actor: shiny plastic, a dark internal element, a stem. Backlight reveals the outline and hides surface print. The ring light builds specular arcs that can erase the internal element or glare across a label. Bars along the axis light the length. Bars across the axis light the ends and change which edges exist. None of these is universally best.
The inspection decides. An internal component wants the lighting that separates it from the barrel. A tip measurement wants the silhouette. A reading job wants the light that does not wash the characters. Pros and cons, not a winner, is the right habit on a line, where a lamp swap is sometimes the entire corrective action.