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LENS GENERAL ADJUSTMENT GUIDE
5. FOCUS-SHIFT CHECK (APERTURE (AMOUNT OF SPHERICAL ABERRATION))
This section describes the check/adjustment of focus-shift amount resulting change of focal-length by aperture setting.
Equipment
• 1000 mm Collimator
• Flange Back Tester
• A-mount Attachment
• Flange Back Gauge (43.50mm)
• Aberration measuring cap (Exclusive for each model)
Note:
It differs in model. Refer to the service manual of each model.
1. Preparations
Perform “1. Preparations” of “3-1. Setting of Flange Back (f’F)”.
2. Checking Method
Note 1:
Note 1:
In case of the zoom lens, some models do not require steps 1) - 5) at the WIDE side. (Refer to the service manual of each
model.)
Note 2:
For the confirmation procedure of a single focus lens, perform steps 8) - 12) described below.
1)
Set the zoom to WIDE end.
2)
Set the focus to infinity (index) or near infinity. (Refer to the service manual of each model.)
3)
Rotate the knob of flange back tester to achieve good focus, read the flange back value. (Make the value to Aw.)
4)
Set the aberration measuring cap (F8 equivalent, for WIDE) on the tip of lens as shown in the Fig.5-1-1.
5)
Rotate the knob of flange back tester to achieve good focus, read the flange back value. (Make the value to Bw.)
6)
According to the result in step 3) and 5), calculate amount of focus-shift (F8 equivalent, for WIDE) using the following formula.
Focus-shift (F8 equivalent, for WIDE) (mm) = (result in step 5) (Bw)) - (result in step 3) (Aw))
7)
Set the zoom to TELE end.
8)
Set the focus to infinity (index) or near infinity. (Refer to the service manual of each model.)
9)
Rotate the knob of flange back tester to achieve good focus, read the flange back value. (Make the value to At.)
10) Set the aberration measuring cap (F8 equivalent, for TELE) on the tip of lens as shown in the Fig.5-1-1.
11) Rotate the knob of flange back tester to achieve good focus, read the flange back value. (Make the value to Bt.)
12) According to the result in step 9) and 11), calculate amount of focus-shift (F8 equivalent, for TELE) using the following formula.
Focus-shift (F8 equivalent, for TELE) (mm) = (result in step 11) (Bt)) - (result in step 9) (At))
Fig.5-1-1
Specification:
The specification of the focus-shift differs in model. Refer to the service manual of each model.
If the adjustment is required, perform the adjustment of the focus shift (Aperture (Amount of Spherical Aberra-
tion)) (Described in the service manual of each manual.).
Aberration measuring cap
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