Find the shadow's source
Put a sheet of paper where you normally write and hold a pen as usual. Watch what happens to the shadow as you move the lamp. For many right-handed writers, a light on the left avoids putting the writing hand between the source and the page; left-handed writers can try the opposite side. Treat that as a starting point and judge the actual desk.
A shelf above the workspace may cast a much larger shadow than your hand. A monitor can block light from a lamp positioned behind it. In both cases, extra brightness may exaggerate the contrast without bringing much more light to the notebook. Try moving the source into a clear line towards the work surface.
An adjustable arm is helpful only if it can reach that position without occupying the keyboard space. Before buying, measure the depth of your desk and look at the lamp's stated reach. A beautifully jointed lamp with a short arm may still leave the important part of a deep desk unlit.
Change tasks during the test
Paper and screens respond differently. A lamp that makes handwritten notes clear may appear as a bright reflection on the monitor. With the screen in its normal position, move the light to the side and adjust the head so it lights the desk rather than shining towards the display.
Check the glossy items too. A laminated reference sheet can reflect the source straight back towards you even when the ordinary paper looks fine. A small change in the sheet's angle or the lamp's position can be enough. There is no need to rearrange the whole workspace to make one reflective object behave.
Use the chair at its usual height. Standing over the desk to assess the light gives a different view of the shade opening and screen reflections. If two people share the desk, let both try it; the adjustable position that suits one person may not be the final position for the other.
Keep the desk usable
Make room for the base, not just the beam. It should sit fully supported without trapping a paper pile or balancing on a cable. A clamp lamp can free surface area, but it needs a desktop edge and thickness that the manufacturer approves. Glass, hollow panels and unusually shaped edges deserve particular care; do not force a clamp onto an unsuitable surface.
Once the position works, decide whether output needs to change. Record the bulb specification if the lamp uses a replaceable bulb. Consider a different compatible output only after testing the existing one with the shade correctly aimed. If you routinely work after dark, make that final check then, with the rest of the room lit as it normally would be. Daylight can conceal a weak evening arrangement.
