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Stepless aperture range
A position
Stepless aperture
Automatic aperture (functioning
when set to the A position)
+1
0.25X 0.20X 0.15X 0.08X 0.029X
0.87 1.0 1.2 2.0 5.0
m
0+
3
/
4
+
1
/
2
+
1
/
4
Exposure correction
Magnification ratios
Distance
Apodization element
Intensity decreases gradually
toward the perimeter
Gradually diffused without losing
shape
Intensity stays the same Line becomes thicker
Specifications
Name
(Model name)
Equivalent
35mm-format
focal length*
1
(mm)
Lens
groups-
elements
Angle of
view 1*
3
Angle of
view 2*
3
Minimum
focus*
4
(m (feet))
Maximum
magnification
(×)
Minimum
f-stop
Filter
diameter
(mm)
Dimensions
(maximum
diameter × height)
(mm (in.))
Mass
(g (oz.))
135mm
F2.8 [T4.5] STF
(SAL135F28)
202.5 6-8*
2
18° 12° 0.87 (2.85) 0.25
f/31
(T/32)
72
Approx. 80×99
(3 1/8×3 7/8)
Approx. 730
(25 3/4)
*
1
The value for equivalent 35mm-format focal length is based on Digital Single Lens Reflex Cameras equipped with an APS-C sized image sensor.
*
2
Including apodization element (1-2)
*
3
The value of angle of view 1 is based on 35mm-format cameras, and that of angle of view 2 is based on Digital Single Lens Reflex Cameras equipped with an APS-C sized image sensor.
*
4
Minimum focus is the shortest distance from the image sensor to the subject.
Included items: Lens (1), Front lens cap (1), Rear lens cap (1), Lens hood (1), Exclusive case (1), Set of printed documentation
Designs and specifications are subject to change without notice.
is a trademark of Sony Corporation.
Aperture
This lens has two aperture settings; A position and a stepless aperture control. Use
the aperture ring to switch between the two settings. T No. is used in both notation
and control on the camera and lens.
To use the stepless aperture setting
This setting allows stepless control of the aperture between T/4.5 - T/6.7. Turn the
aperture ring to set the desired aperture.
• This stepless range is recommended when a large aperture is desired.
• Set your camera to A mode or M mode when using this setting. (In P mode or scene-
selection setting, the settings will be the same as A mode. In S mode, the settings will
be the same as M mode.)
• A slight click can be felt at the T/4.5, T/5.6, and T/6.7 marks.
• The index marks between T/4.5 and T/5.6 represent 1/3 aperture values.
• Stop-down metering is used when the stepless aperture is selected.
• When shooting, the aperture values set by the aperture ring are used. Those values are
not accurately reflected in the values displayed or recorded by the camera.
To use the A position
This setting (A position) allows the lens to be used the same way as traditional manual-focus lenses. Set the aperture on
your camera.
• All exposure modes (P, A, S, M) can be used on the camera.
Aperture Information
This lens has two apertures; the stepless aperture, manually controlled with
the aperture ring, and the automatic aperture (A position), controlled by
the camera. In the stepless aperture setting, emphasis is put on the aperture
shape, which is rounder than the automatic aperture. For large aperture
settings, selecting the stepless aperture is recommended.
Depth of field (in meters)
When focus is set on a subject, anything at that same distance will appear sharp, and anything within a certain range
before and beyond the subject will also appear in focus; this is called depth of field. Depth of field depends on the
subject distance and aperture you choose.
T/4.5 T/5.6 T/6.7 T/8 T/11 T/16 T/22 T/32
∞
∞
114.8
∞
97.8
∞
82.3
∞
69.2
∞
49.0
∞
34.7
∞
24.6
∞
17.4
10m
10.91
9.23
11.08
9.11
11.32
8.96
11.61
8.79
12.44
8.37
13.84
7.84
16.48
7.20
22.58
6.46
5m
5.21
4.81
5.24
4.78
5.29
4.74
5.35
4.69
5.51
4.58
5.76
4.42
6.15
4.22
6.80
3.97
3m
3.068
2.935
3.080
2.924
3.096
2.910
3.115
2.894
3.165
2.852
3.239
2.795
3.350
2.719
3.522
2.618
2m
2.027
1.974
2.032
1.969
2.038
1.963
2.046
1.956
2.065
1.939
2.094
1.915
2.135
1.882
2.198
1.837
1.5m
1.514
1.478
1.156
1.484
1.519
1.481
1.523
1.478
1.533
1.469
1.547
1.456
1.567
1.439
1.597
1.415
1.2m
1.028
1.192
1.209
1.191
1.211
1.189
1.213
1.187
1.219
1.182
1.226
1.175
1.238
1.165
1.254
1.151
1.0m
1.005
0.995
1.006
0.994
1.007
0.993
1.008
0.992
1.011
0.989
1.016
0.985
1.023
0.978
1.033
0.970
0.87m
0.873
0.867
0.874
0.866
0.874
0.866
0.875
0.865
0.877
0.863
0.881
0.860
0.885
0.856
0.891
0.850
The depth-of-field scale and depth-of-field table are for 35mm-format cameras. The depth of field is shallower when you
use Digital Single Lens Reflex Cameras equipped with an APS-C sized image sensor.
Exposure compensation
As the magnification increases, the amount of light reaching the image sensor decreases. This is automatically
compensated in all autoexposure modes, or in the manual exposure mode as long as the exposure is adjusted according
to the camera’s meter index. If your camera is set to the manual exposure mode and you are using a hand-held exposure
meter, or if your camera is set to the manual exposure mode and you are using the Manual Flash Control function
available on some external flash units, adjust exposure accordingly.
(E.g., when adjusting by the aperture, +1 means opening the aperture 1 more stop.)
About Apodization
A special “apodization element” is situated near the aperture of the lens
optical system. This special optical element is a type of ND filter which
gradually becomes thicker (darker) towards the perimeter, thereby reducing
the amount of light that passes through around the outer perimeter. The
aperture of this lens is indicated and controlled by the T No., which
compensates for the reduction imposed by the special apodization element.
The T No. can be used as the F No. on a normal lens when the exposure is
determined.
Principle of defocusing effect improvement
Defocusing of a dot Defocusing of a line
This lens
Theoretical ideal
traditional lens
Defocused images appear as blurred clusters of dots. A lens with well compensated aberration reproduces the
image shape accurately, but cannot produce smooth blurs in a defocused area. There may be unpleasant blurs,
which for example, make one line appear to be doubled, depending on the way of compensation. This lens adopts a
special apodization element that provides a gradually diffused image toward the perimeter without losing the core
shape. In other words, it provides soft and natural defocusing without transforming the original shape unnaturally.