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4-9
SAL18552 (DT 3.5-5.6/18-55 SAM Ⅱ) (DT 18-55mm F3.5-5.6 SAM II)
3. The focusing error amount check
1) Open the images shot with the lens to be tested and the AE master lens by the image display software on the PC. (Display the images at
1) Open the images shot with the lens to be tested and the AE master lens by the image display software on the PC. (Display the images at
the same pixel magnification.)
2) Check the displacement between the focus position (peak of image-formation) of the lens to be tested and the focus position of the AE
master lens. (Refer to Fig. 4-5-4 and Fig. 4-5-5.)
3) Compare the error amount in step 2) with the reference value of Table 4-5-3 and check whether the error amount is within the accept-
able range. If the error amount is outside of the range, perform 4-7-5.
⊿
SB Check/Write .
Reference value
Focal length/
18 mm
Distance
(mm)
0.36 m (20 times)
0
±
23
0.72 m (40 times)
0
±
92
1.08 m (60 times)
0
±
208
Focal length/
24 mm
Distance
(mm)
0.48 m (20 times)
0
±
26
0.96 m (40 times)
0
±
106
1.44 m (60 times)
0
±
238
Focal length/
28 mm
Distance
(mm)
0.56 m (20 times)
0
±
30
1.12 m (40 times)
0
±
119
1.68 m (60 times)
0
±
267
Focal length/
35 mm
Distance
(mm)
0.7 m (20 times)
0
±
33
1.4 m (40 times)
0
±
132
2.1 m (60 times)
0
±
297
Focal length/
55 mm
Distance
(mm)
1.1 m (20 times)
0
±
37
2.2 m (40 times)
0
±
148
3.3 m (60 times)
0
±
333
Table
4-5-3
<For reference 1: shooting image by AE master lens> (Fig. 4-5-4)
• Assume it standard image in the setting environment.
• If the peak of image-formation is to equal distance with AF assist chart position, it is ideal. In actual fact, the image of before and
• Assume it standard image in the setting environment.
• If the peak of image-formation is to equal distance with AF assist chart position, it is ideal. In actual fact, the image of before and
behind the peak is displayed. (Because the environment, the individual difference of camera and lens conditions are combined.)
• The image of before and behind the peak, assume it reference standard image.
• When shooting the image with sharpness setting of the camera to + side, it is easy to distinguish the peak of imaging area remarkably.
• When shooting the image with sharpness setting of the camera to + side, it is easy to distinguish the peak of imaging area remarkably.
Enlargement of same pixel magnification
Example of image shot with
a certain AE master lens under
a certain environment.
a certain AE master lens under
a certain environment.
Identifying the peak position of
image-formation:
• Center of sharpest area
• Center of area with less color fogged
- Front defocus area: Magenta fogged
- Rear defocus area: Green fogged
image-formation:
• Center of sharpest area
• Center of area with less color fogged
- Front defocus area: Magenta fogged
- Rear defocus area: Green fogged
Example where peak position accidentally matches
the AF Assist Chart position
the AF Assist Chart position
Fig.
4-5-4
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