Sony Alpha DT lenses
Sony’s range of DT lenses are designed for DSLRs with smaller ‘APS-C’ sized sensors. These include the Alpha A100, A200, A300, A350 and A700 models. DT lens optics are only corrected for use on bodies with these smaller sensors. They can be fitted to full-frame bodies like the A900, but the camera will automatically crop the uncorrected border areas to give the same coverage as an APS-C model.
For a full explanation of lens specifications and examples of coverage at different focal lengths, check out our Camera Labs Lens Buyers Guide.
So whether you have a DT lens mounted on an APS-C or a full-frame Alpha body, its equivalent focal length will always be multiplied by 1.5 times. So the general-purpose DT 18-70mm lens will deliver a field of view equivalent to a 27-105mm.