# Chapter 25 - Optical Instruments - Questions: 1

Moving closer to the subject decreases the object distance.

#### Work Step by Step

The focal length of the lens stays constant. Equation 23-8, $\frac{1}{d_{o}} + \frac{1}{d_{i}} = \frac{1}{f}$, tells us that if $d_{o}$ decreases and f stays the same, the image distance $d_{i}$ must increase. The camera lens moves farther away from the sensor.

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