Sony DT 18-55 mm f/ 3.5-5.6 SAM II Lens Specification Guide

4-17

SAL18200 (3.5-6.3/18-200) (DT 18-200mm F3.5-6.3)

This section describes the check/adjustment of focus-shift amount resulting change of focal-length by aperture setting.

• 1000 mm Collimator

• Flange Back Tester

• A-mount Attachment

• Flange Back Gauge (43.50mm)

• Aberration measuring cap 62mm

1)

Perform “1. Preparations” of “4-4-1. Optical Axis Check/Adjustment and Focus-shift Flange Back (f’F) Check”.

2)

Turn the zoom ring of the checking lens, and set the focal length to 200 mm.

3)

Turn the focus ring until the flange back (f’F) at focal length (200 mm) is “44.60 

±0.03 mm”.

1)

Set the lens aperture to the open aperture position, and measure the flange back (f’F).

2)

Set the aberration measuring cap 62mm (F11 equivalent) on the tip of lens as shown in the Fig.4-5-1, then measure the flange back

(f’F).

3)

Calculate amount of focus-shift using the following formula, and check that the specification is satisfied.

When the focus-shift is out of specification, perform “3. Adjusting Method”.

The focus-shift amount of the checking lens is difference between the flange back (f’F) of open aperture and flange back

(f’F) reading (using aberration measuring cap 62mm).

Focus-shift = flange back (f’F) of open aperture reading - flange back (f’F) reading (using aberration measuring cap 62mm)

Focus-shift (mm) = –0.12 to +0.21

Aberration measuring cap 62mm