Sigma's budget super-telephoto for Sony A — the 135-400mm APO for affordable long reach.
The Sigma 135-400mm f/4.5-5.6 APO DG is a budget super-telephoto zoom for Sony A mount. Covering 135-400mm with APO elements for chromatic correction, it provided affordable super-telephoto reach. The DG designation indicates digital sensor optimisation. A budget gateway to long-range wildlife and sports photography on the A-mount system.
Optical performance is basic with APO elements providing better chromatic correction than non-APO alternatives. Centre sharpness is acceptable at shorter focal lengths, weakening at 400mm. The slow f/5.6 at 400mm demands bright conditions. No stabilisation — body SR provides some compensation. Adequate for casual super-telephoto work in daylight.
Sony A mount. Filter thread is 77mm. Weight is approximately 1,280 grams — heavy. Build quality is adequate. APO elements help but the overall optical quality lags behind modern alternatives. Tripod collar included. Benefits from Sony body-based SteadyShot INSIDE stabilisation. The A-mount system is discontinued.
Very cheap on the used market. Check zoom mechanism and AF. The 400mm reach at budget pricing was the appeal. Thoroughly superseded by the Sigma 150-600mm Contemporary and similar modern alternatives. Only of interest at extremely low prices for casual super-telephoto experimentation.