Good But Not Great
The SONY VCL-DH1758 1.7x Tele Converter is the best unit we've tried todate (by a long shot) but still not quite as good as simply using PhotoZoom software to enlarge an image.
The unit is well built, the optics are nicely coated and it is miles ahead of the Vivitar teleconverter, which we threw in the garbage after testing, and better than two other similar teleconverters.
If there is ever a future addition of this teleconverter, I would suggest one with 72mm threads to fit on most current long lenses. We had to ring up its 58mm to 72mm to fit on the Sony RX10 III. As a result of the 58mm back diameter, images had severe vignetting up to about 300mm zoom, after 300mm the small amount of vignetting was acceptable.
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