Here, take a look at Photomic S a little for example.
This finder is a match needle type with two-point LED indicators.

• Attach Photmic S finder as you saw previous page.
  Then, as shown in the figures, turn the aperture ring from one end to the other end.
  By doing this procedure, full-aperture metering is enable to be used on F2.
  In addition, the lenses that are able to be used at full-aperture metering are those of F1.2-F5.6 at maximum aperture.