Update:
Returned to the store already. They will try to fix it first. I only showed them the manual testing off camera. They took it back no problem. Thanks everyone.
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I bought an used af540fgz. Tried it with K5, using both da 18-55wr and da35 2.4.
When camera in AV mode, flash in digital pttl mode, shutter speed never changed no matter where I aimed to meter or what aperture I set.
So I set both camera and flash to manual mode, kept same camera exposure setting and adjusted different flash power output from 1/1 to 1/64, but I always get same extent overexposed images.
Never used Pttl flash before, am I missing sth here or just a defective flash. Luckily I bought from store and can return it.
Last edited by Phenix; 06-30-2016 at 08:15 AM.