Final answer:
False. PD measuring instruments are not prone to more parallax errors compared to those taken using a PD ruler. PD measuring instruments are less prone to parallax errors if used correctly.
Step-by-step explanation:
False. PD measuring instruments are not prone to more parallax errors compared to those taken using a PD ruler. Parallax errors occur when the position of the eye is not directly in line with the measurement scale, resulting in an error in the measurement. PD measuring instruments, such as a PD ruler or a pupillometer, are specifically designed to minimize parallax errors by ensuring accurate positioning of the eyes.
On the other hand, using a PD ruler (or pupillometer) without proper positioning and alignment may result in parallax errors if the student's eye is not in line with the measurement scale.
Therefore, PD measuring instruments are less prone to parallax errors if used correctly.