Vivitar's compact telephoto — the 75-150mm f/3.8 constant aperture zoom.
The Vivitar 75-150mm f/3.8 is a compact telephoto zoom with constant f/3.8 aperture. Vivitar lenses were manufactured by various Japanese OEMs — quality depends on the manufacturer. The constant f/3.8 provides consistent exposure. The compact 75-150mm range covers portrait through moderate telephoto. Mount not specified — verify before purchase.
Quality depends on OEM manufacturer — some Vivitar lenses are very good (Komine, Tokina manufactured). The constant f/3.8 is a practical advantage. The compact 75-150mm is a useful range. Check serial number prefix to identify manufacturer. Build quality varies. The constant aperture is the distinguishing feature versus variable alternatives.
Mount not specified — verify. Weight varies. Build quality varies by OEM. The constant f/3.8 and compact range are the practical features. Vivitar lenses are valued differently by OEM — identify the manufacturer via serial number for quality assessment. Manual focus likely on most versions.
Very cheap. The constant f/3.8 adds value. Verify mount and check OEM via serial number. Quality varies dramatically between OEM manufacturers. The compact range and constant aperture are the practical selling points. Good copies from quality OEMs are genuine bargains.