Promaster Spectrum 7 Auto Teleconverter for Minolta

The ProMaster Spectrum 7 Auto Teleconverter for Minolta is a third-party teleconverter designed to extend the effective focal length of compatible Minolta-mount autofocus lenses, offering photographers extra telephoto reach without purchasing a separate longer lens. It mounts between the camera body and the attached lens, available in versions built for Minolta’s Maxxum/Alpha AF mount as well as the older manual-focus MD mount.

Depending on the specific model, the teleconverter is offered in 1.7x and 2x magnification factors. The 1.7x version uses an 8-pin electronic connection to maintain full autofocus and metering compatibility with Minolta Maxxum AF lenses, built from 4 elements in 4 groups with multicoated optics, and results in a modest light loss of approximately 1.5 stops, recommended for use with lenses having a maximum aperture of f/4.5 or faster. The 2x version, designed for Minolta’s manual-focus MD mount, similarly extends the attached lens’s effective focal length, doubling it at the cost of a more substantial two-stop light loss typical of 2x converters.

With the 1.7x AF version, autofocus and full metering remain functional across most compatible Minolta lenses, including both prime and zoom optics, letting photographers retain largely normal shooting behavior at the extended focal length, though some additional AF hunting can occur, particularly with longer host lenses. The teleconverter communicates lens data to the camera body, and on APS-C Sony/Minolta bodies used with an adapter, the extended focal length combines with the camera’s own crop factor for an even longer effective field of view.

Build quality includes a compact, lightweight housing with a ribbed grip for secure handling, and the unit is manufactured in Japan.

Key Features
– Teleconverter for Minolta Maxxum/Alpha AF-mount or Minolta MD-mount lenses (version-dependent)
– Available in 1.7x and 2x magnification factors
– 1.7x AF version: 8-pin electronic mount, full autofocus and metering compatibility
– 4 elements in 4 groups, multicoated optics (1.7x version)
– Approximately 1.5-stop light loss (1.7x version); greater light loss on 2x version
– Recommended for use with lenses of f/4.5 maximum aperture or faster (1.7x version)
– Extends effective focal length of compatible host lens
– Compact, lightweight construction with ribbed grip
– Made in Japan