“PENTAX released the long-awaited 1.4x autofocus teleconverter in March, 2014. This handy accessory mounts between your existing DSLR lens and the camera mount to increase the effective focal length by 1.4x, giving you extra reach at the expense of one stop of light. For example, a 300mm F4 lens paired with the teleconverter would give you the same field of view and maximum aperture as a 420mm F5.6 lens. We feel that the teleconverter is an important addition to the Pentax lens lineup, which currently has a limited number of extreme telephoto lenses.”
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“This is actually the first converter from Pentax that supports autofocus – until now autofocus was only available with select third-party converters, many of which were plagued by issues such as poor availability, poor image quality, or a limited feature set.”
Read more at pentaxforums.com
