Sony DT 18-250mm f/3.5-6.3 lens
Review Date : Fri, 1 Jan 2010
Author : Jon Tarrant
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How does this Sony superzoom stand up to the competition? This Sony DT 18-250mm f/3.5-6.3 lens review from What Digital Camera aims to find out.
|Cons:||No image stabilisation|
This lens is designed to cover the APS-C format but was tested using a full-frame Sony A900 body, which automatically records the smaller area when a DT lens is fitted. Although that is a clever trick, the viewfinder does not clearly define the APS-C area, making it difficult to frame pictures quickly at speed. Most people will never meet this problem, but it is worth mentioning in case any full-frame owners think of buying a DT lens such as this.
In common with other manufacturers, Sony has positioned its superzoom's focusing ring towards the front of the lens and, as such, it is obstructed when the supplied petal-type lens hood is reversed for storage. More seriously, but not unusually, part of the zoom ring is also obstructed.
Automatic focusing is not particularly brisk, but proved to be very reliable on the A900 body. The manual-focusing ring does not have a particularly nice feel and rotates when the lens is set to AF mode: the need to avoid hampering the ring's rotation makes it difficult to grip the lens firmly, especially at longer focal-length settings.
Curiously, despite being specified with a maximum aperture that varies from f/3.5 to f/6.3, the smallest recorded maximum aperture was f/5.6. The same oddity also appeared at the minimum aperture end of the F-stop scale, where Sony specifies f/40 but the zoom's EXIF data showed f/38.
Chromatic aberration is detectable at both ends of the zoom range (with the fringe colours reversed at opposite extremes) in technical images and demanding real-world pictures, but not in more everyday images.
In terms of MTF performance, Sony's lens works best as a wideangle zoom: it returns a resolution of 0.25 cycles-per-pixel or better at 70mm and below down to f/16, but is slightly weaker at longer focal-length settings. That said, the MTF curves are neatly grouped and indicate smooth transitions rather than abrupt changes in behaviour.
Overall, this is a nice lens that feels solid and inspires confidence. Its price may be only slightly less than that of some other lenses that include image-stabilisation technology, but it is still a sound investment.