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Sony 18-70mm f/3.5-5.6 DT ( SAL-1870 ) - Review / Lab Test Report |
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Lens Reviews -
Sony Alpha/NEX (APS-C)
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Review by Klaus Schroiff, published December 2007
Introduction
The Sony 18-70mm f/3.5-5.6 DT is the bottom end standard zoom lens of the
Alpha systems. It is usually not sold separately but in camera-lens "kits".
As a designated "DT" lens it can only be used on Sony/Minolta APS-C DSLRs.
Its field of view is equivalent to 27-105mm on full format cameras - a quite
attractive 4x zoom ratio covering wide to moderate tele range.
The build quality of the lens is relatively decent for a kit zoom lens
although it is a plastic construction down to the lens mount. The very broad,
rubberized zoom ring operates smooth whereas the tiny focus ring at the very front
of the inner lens tube feels rather cheap and it is obvious that Sony does
not expect anyone to use it seriously. Consequently the front element does
also rotate during focusing. The fluted rubber of the zoom ring provides lots
of grip but it also tends to collect quite a bit of dust.
As you can see below the lens extends slightly towards the long and the wide end
of the zoom range. It has its shortest length at about 35mm.
Similar to the Zeiss 16-80mm the Sony lens does still rely on the conventional
focusing system driven by the camera (via a slotted drive screw). The AF produces
a moderate degree of noise during operations but it is very fast and accurate
(on the Alpha 700).
| Specifications |
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| Equiv. focal length | 27-105 mm (full format equivalent) |
| Equiv. aperture | f/5.3-f/8.4 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 11 elements in 9 groups inc. 1 aspherical and 1 AD elements |
| Number of aperture blades | 7 (rounded) |
| min. focus distance | 0.38 m (max. magnification ratio 1:4) |
| Dimensions | 77 x 66 mm |
| Weight | 240 g |
| Filter size | 55 mm (rotating) |
| Hood | barrel-shaped, snap-on, supplied |
| Other features | - |
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