New answers tagged sigma
It's hard to say for sure, but if the issue only appears when the lens is mounted on the camera and when it's powered on, it does suggest that the issue is something to do with the electrics in the lens. Have you confirmed that the issue is still occurring with the lens on another camera body? If so, does the speed at which you zoom make any difference - ...
I believe a lot of cheaper hypersonic montors (HSM) [or USM for Canon glass] don't have great quality control and can produce that kind of noise. Likewise, I've personally had a Canon USM lens that was vibrated too much in a case emit that kind of noise, too. Your best bet would be to send the Sigma back for warranty service (or take it into a shop) to get ...
If the lens is similar to the Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM, it uses an ultrasonic (Hypersonic, in marketing parlance) motor for focusing. These motors can be smoother (less backlash or overshoot) than traditional electromagnet-based rotary motors, but apparently the "ultrasonic" ratcheting is not quite beyond your hearing range. This is nothing ...
It is a Minolta mount! Have a Look at the rear cap of this lens. (If you still have) There you should see "For ..."
Naaa This is the Sigma SA mount. https://en.wikipedia.org/wiki/Sigma_SA-mount which is like a cross between the pentax K mount (mechanically) and the canon mount (electronically)
I think you've got a Minolta A-mount lens. Compare to this photo (image borrowed from here): Minolta and Konica merged at some point and were subsequently acquired by Sony, and this mount is apparently still used by Sony as the "Alpha mount system".
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