Purple haze in photo corners?

Carl Mucks said:

it's likely a vignetting correction that amplifies the noise. The lens has some 2.5 stops falloff at the corners, so the ISO at the corners in your case is about 18000, thus a lot of noise.

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Hye said:

Carl Mucks said:

it's likely a vignetting correction that amplifies the noise. The lens has some 2.5 stops falloff at the corners, so the ISO at the corners in your case is about 18000, thus a lot of noise.

Click to expand...

I don't think so:

(1) It doesn't have the shape of vignetting correction, mostly along the bottom and left edge.

(2) It occurs even if you do a dark exposure without a lens attached.

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joryphoto said:

So I shot this long exposure on a Sony A7ii with a Zeiss Batis 25mm f2. Settings used: ISO, 3200 f2 30sec exposure. When I bring up the shadows in lightroom, I get this weird purple noise in the photo.

I keep finding conflicting information online about what this coloring is and how to avoid it. Anyone also experience this / have any suggestions?

Shot straight RAW:



Profile correct + max shadow add

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Carl Mucks said:

Hye said:

Carl Mucks said:

it's likely a vignetting correction that amplifies the noise. The lens has some 2.5 stops falloff at the corners, so the ISO at the corners in your case is about 18000, thus a lot of noise.

Click to expand...

I don't think so:

(1) It doesn't have the shape of vignetting correction, mostly along the bottom and left edge.

(2) It occurs even if you do a dark exposure without a lens attached.

Click to expand...

I don't know how you did your experiments. My experiments clearly show the vignetting correction increasing the noise as expected when using the native lenses, and there is an even noise over all the frame when using manual lenses.

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