A new prime lens for general photography makes a welcome addition to Sony's 'Easy Choice' lens range.The DT 35mm f/1.8 SAM (SAL35F18) was one of three new lenses announced by Sony in July, 2010. Designed to provide an affordable, compact and lightweight prime lens with a popular focal length for both entry-level and advanced photographers it's less than one fifth of the price of Sony's other 35mm prime lens, the SAL35F14G, which retails for $2,699 and is the only in line-up. . . [more]
The DT 35mm f/1.8 SAM (SAL35F18) was one of three new lenses announced by Sony in July, 2010. Designed to provide an affordable, compact and lightweight prime lens with a popular focal length for both entry-level and advanced photographers it's less than one fifth of the price of Sony's other 35mm prime lens, the SAL35F14G, which retails for $2,699 and is the only in line-up.
The DT 35mm f/1.8 joins Sony's ‘Easy Choice' series lenses, covering an angle of view that is roughly equivalent to the ‘normal' 50mm focal length on a 35mm camera. Ideal for general photography, it can be used for portraiture, landscape shots and close-ups and its relatively wide maximum aperture is useful for hand-held shooting in low light.
The new Sony DT 35mm f/1.8 SAM (SAL35F18) lens. (Source: Sony.)
Because it weighs only 170 grams, it is compact enough to add to a standard kit lens system without significantly increasing the weight of the owner's camera bag. Compared with the SAL35F14G, the optical design of this lens is simple, with only six elements arranged in five groups. No exotic glasses have been included. The table below compares key features of Sony's two 35mm lenses.
35mm equivalent focal length
Angle of View (APS)
Lens Groups / Elements
5 / 6
8 / 10
Depth of field Scale
Non-rotating Focusing Ring in AF Mode
Dimensions (Diameter x Length)
70 x 52 mm
69 x 76mm
Because of its relatively low price tag, this lens is made almost entirely of plastic with a plastic mounting plate and barrel. A narrow metal ring around the barrel, approximately 15mm back from the front of the lens, is the only indicator of any other materials used in construction.
Build quality is good for a plastic lens carrying the ‘Made in China' label. The plastic barrel has smooth finish and the lens comes with a cylindrical lens hood, along with front and end caps. Several multi-lingual instruction leaflets are also provided.
An AF/MF slider switch is located on the left side of the barrel. The focusing ring is approximately 8 mm wide, with a rubberised tip that lacks ridges for a secure grip. It's rather loose, making precise focusing tricky. Distance markings in metres and feet are stamped on the barrel just behind the leading edge.
Although the focusing ring rotates in AF mode, all focusing is internal, The 55 mm diameter filter ring is on the non-rotating inner barrel, which means you can use angle-critical filters without having to re-adjust them when focus is changed.
On the Sony SLT-A33 camera body used for our tests, the review lens was a comfortable, well-balanced fit and its light weight was a good match to the relatively light camera body. The plastic mounting plate attached securely and the focusing ring and AF/MF switch were within easy reach.
The focusing ring moved through roughly one quarter of a turn in MF mode. We would have liked the movement to be slightly tighter but found no reason to complain about manual focusing accuracy.
The Smooth Autofocus Motor (SAM) in-lens AF drive motor was introduced in 2009 to provide faster, quieter focusing. It's a step up from having focus driven by a motor in the camera body but we found it wasn't quite as quick or quiet as the ultrasonic drive motors in premium lenses. However, hunting only occurred with low-contrast subjects in low light levels.
Imatest showed the review lens to be a competent performer that delivered its highest resolution at mid-range focal lengths (f/3.5 to f/9), with a slow decline in resolution from the peak at f/6.3 as diffraction began to influence image quality. Some edge softening was detected at wider apertures, although it was relatively minor for a lens at this price point. The graph below shows the results of our tests.
Lateral chromatic aberration was low in our Imatest tests, dipping into the ‘negligible' category between f/2.2 and f/5 and never rising above the half-way point in the ‘low' division. In the graph below, the red line marks the border between ‘negligible' and ‘low' CA, while the green line represents the transition from ‘low' to ‘moderate' CA.
Slight coloured fringing was found in some outdoor shots, taken in contrasty lighting. However, it tended to be close to the edges, leaving the central two thirds of the frame largely unaffected.
The slight barrel distortion was not noticeable enough to affect most potential users of this lens and vignetting was negligible at the widest aperture. It was difficult to force the lens to flare by pointing it directly towards a bright light source and normal backlighting was handled without problems.
The D-range adjustments on the a33 enabled shadow detail to be recorded in contrasty lighting. Bokeh was smooth and reasonably attractive, although not outstandingly beautiful, either at f/1.8 or with the aperture stopped down.
Buy this lens if:
- You want an affordable general-purpose prime lens for a Sony DSLR body.
- You'd like a lens that requires no readjustment when you fit polarisers and graduated filters.
- You require minimal distortion and vignetting
Don't buy this lens if:
- You prefer metal mounting plates.
- You require high resolution at the widest apertures.
Based on JPEG files from the α33 camera.
Vignetting at f/1.8.
Rectilinear distortion; ISO 100, 1/160 second at f/9.
ISO 100, 1/250 second at f/11.
A crop from a 100% enlargement of the above image showing slight coloured fringing.
ISO 100, 1/160 second at f/6.3.
A crop from a 100% enlargement of the above image showing a slight loss of sharpness at the edges of the frame but minimal rectilinear distortion. (Coloured fringing can also be seen.)
Close-up at f/1.8; 1/640 second at ISO 100.
ISO 100, 1/200 second at f/8.
Contre-jour lighting; ISO 100, 1/250 second at f/8.
ISO 100, 1/160 second at f/6.3.
ISO 400, 1/20 second at f/5.6.
ISO 400, 1/60 second at f/5.
ISO 100, 1/60 second at f/2.5.
ISO 320, 1/60 second at f/9.
ISO 400, 1/15 second at f/8.
Picture angle: 44 degrees (equivalent to 52.5mm in 35mm format)
Minimum aperture: f/22
Lens construction: Six elements in five groups
Lens mounts: Sony A-mount
Diaphragm Blades: 7 (circular aperture)
Focus drive: Smooth Autofocus Motor (SAM)
Stabilisation: Relies on stabilisation in the camera body
Minimum focus: 23 cm
Maximum magnification: 0.25 x
Filter size: 55 mm
Dimensions (Diameter x L): 70 x 52 mm
Weight: 170 grams
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