Sony ILCA-77M2 - Manual (Page 85)

The mark shows the location of the image sensor*. When you measure the exact distance
between the product and the subject, refer to the position of the horizontal line.
*
The image sensor is the part that converts the light source to a digital signal.
Note
If the subject is closer than the minimum shooting distance of the lens, the focus cannot be
confirmed. Make sure you put enough distance between the subject and the product.
[91] How to Use Using shooting functions Adjusting the focus
AF Range Control
You can restrict the autofocus range to focus on a subject without interference from objects in the
background and foreground. The [AF Range Control] function is assigned to the C (Custom) button with
the default settings.
1. Press the C (Custom) button
(A).
2. Set the maximum shooting distance using the front dial and set the minimum shooting distance
using the rear dial.