Dark corners at 210mm on a Sony 55-210mm: normal vignetting or an obstruction?

Asked 10/11/2015

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I shot an air show with a Sony a6000 and the Sony 55-210mm f/4.5-6.3 at 210mm, f/6.3, 1/1250, ISO 100. In some images I see darkening in the corners against the sky. No filters were used, the posted images are the full frame scaled down, and in the third example it happened in only one frame of a burst.

Are the first two examples just normal vignetting at the long end and wide open, or does this suggest a problem with the lens? And what could cause a single frame to have much darker shading along one edge, like the third image?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

2 Answers

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The first two look like typical light falloff at the corners that is normal for telephoto shots taken with a wide open aperture. Even though the aperture is f/6.3, that is as wide as that lens goes. With the darker the sky the falloff will be more noticeable due to the way light curves and gamma are applied to the linear data coming off the sensor. In the first image the differences between center and corners are emphasized because they fall on the part of a typical response curve that has the steepest slope between the two intensities. With the brighter sky in the second shot the differences are minimized because the slope of the light curve levels out quite a bit near the top.

The third shot, however, looks like your lens hood or another obstruction was blocking the top edge of your lens.

Originally by user15871. Source · Licensed CC BY-SA 4.0

user15871

10y ago

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AI Answer

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The first two examples sound like normal vignetting/light falloff: at 210mm and f/6.3 you’re shooting the lens wide open, and corner darkening is most visible against an even blue sky. That kind of falloff is usually fairly symmetrical and often improves if you stop down.

The third example is different. A single frame with much darker shading along one edge is unlikely to be normal lens vignetting. It points more to a temporary obstruction, such as a mis-mounted or incorrect lens hood, or another object briefly blocking the edge of the lens. Community answers also note filters or stacked filters can cause this, but you said no filters were used.

So: first two = likely normal optical vignetting; third = likely something physically intruding into the frame rather than the lens’s usual behavior.

UniqueBot

AI

10y ago

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