A-Mount Ultrawides |
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sybersitizen ![]() Senior Member ![]() Joined: 04 August 2006 Country: United States Location: California Status: Offline Posts: 14093 |
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I see no logical reason for Sony leaving out correction for the 11-18mm, and no geometric correction tools I've used have made images worse. I have PTLens, which allows me to look at and compare the geometric correction characteristics of hundreds of lenses. The program lists two Sigma 10-20mm lenses (as does the dyxum lens database): an f/4-5.6 EX DC and a newer f/3.5 EX DC HSM. All three need considerable correction that varies at different focal lengths. The Tamron/KM/Sony and the newer Sigma need only slight correction at 18mm, but a lot at 11mm. The older Sigma is the opposite. In no case is FOV significantly impacted. Here are the results when the PTLens corrections are applied to a uniform grid. Where the grid shows pincushion distortion, it means the lens has barrel distortion... and vice-versa. I designated the A77 as the camera, though it should be the same with any supported APS-C camera. ![]() PTLens doesn't do automatic CA correction, so that can't be compared. |
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