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Strange A7Sii artefacts. Am I alone?


Guillaume Borkhataria

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Hi guys, I'm experiencing these weird artefacts in underexposed areas of my images, these dark boxes appear in the same areas in underexposed parts.

4K / ISO1600 / f2.8 / 1/100
S-Log3 / SGamut.Cine

I over exposed the faces by about 1.5 - 2 stops over.

Ive pushed some of the stills in photoshop to highlight the artefacts. Any advise with regard to my artefact issues would be greatly appreciated. Is something wrong with my A7Sii?

Many thanks!

artefact-02.png

artefact-03.png

Artefect-example.png

CUBIST VICTIMS.00_29_45_07.Still008.jpg

CUBIST VICTIMS.00_29_53_19.Still001.jpg

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Guest Ebrahim Saadawi

First:

Test out where the problem comes from as follows in order (any dark area around you now):

1 -Shoot with a different lens. It doesn't look like an optical issue but just to rule it out. if still remais:

2- Shoot a RAW still image. If problem is there --> sensor problem. End. If it's not there: 

3- Shoot video. If it appears only in video --> processing/codec problem. So then:

4- Shoot video at Slog and PP off. See If it appears only in one/two profiles then a profile issue. If it appears in all pps:

5- Connect the camera to TV via HDMI and see if it's there. If it goes away --> codec/NR issue

 

Make screen grabs of all these tests. Then share them here, other users will try to replicate the bug using the tests you gave: 

if they find it too --> an A7sII bug. If they don't --> your sample bug --> return to retailer/Sony along with the tests I listed. 

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Hi Ebrahim

Many thanks for your suggestion. I've investigated the issue a little and here are my findings:

EDIT: I have not labelled the attached photos properly, but essentially, the JPG are the ones with the artefacts, followed by a manipulated RAW export to show that RAW did not replicate the artefact

Lens test: [Both lenses are attached to my A7Sii body using the Metabones: Canon EF Lens to Sony E Mount T Smart Adapter (Mark IV)]

- Can replicate with Canon EF 70-200 F2.8 Lii

- Can replicate Canon EF 24-70 F2.8 Li

OBSERVATION: The issue is visible on both lenses, the pattern is the same. The pattern does not change when I zoom the 24-7, however, the pattern changes on the 70-200 lens as I zoom in and out. It is not a gradual change, it is a static change that changes on roughly 4 increments, 70mm, 100mm, 135mm, 200mm.

- I cannot replicate the issue when no lens is attached. (exposed sensor)

- I cannot replicate the issue when another lens is held in front of the body without the adapter (not properly attached to body)

RAW test

- I cannot replicate the issue with Uncompressed RAW (.ARW) files.

- I cannot replicate the issue with Compressed RAW (.ARW) files.

- I can recreate the problem on .JPG stills.

Video test

Watch this link to view my video test: https://www.youtube.com/watch?v=GKtJUESOpyI&feature=youtu.be (I've uploaded in 4K but YT compression may make it hard to notice)

- Replicate issue in underexposed areas (below 2 stops). It becomes very hard to notice when when there is almost no light. (try very dim light)

- Replicate between ISO 1600 - 5000

OBSERVATION: As visible in the video there is a random change in the hue when underexposed and in low light. It flickers from a red hue to a blue hue. The issue is present but harder to see when the hue is blue.

Picture Profile test

The only variable that affects the issue is Gamma. Color mode does not affect the issue, only making it easier to see in certain color modes.

- Can replicate the issue in Gamma: SLog3 / SLog2 / ITU709(800%)

- Cannot replicate the issue with any other gamma setting

 

Findings summary

- The focal length of my 70-200 has impact on the pattern of the issue

- I cannot rule out the Metabones adapter as the problem (although I cannot see how the adapter would affect the image, it only sends signal to change aperture, focus motor and IS)

- I can't replicate the issue with RAW images, but I can with stills. So I don't believe something is wrong with the sensor. 

- Only the Gamma variable in picture profile affects it. Appearing only in Slog2 Slog3 and ITU709(800%)

- A random change in the image hue (in low light) makes the issue more visible and less visible.

I have uploaded some images and a video link. For you guys to have a look if you're interested.

 

Is anyone able to replicate my issue?

70mm JPG V2.jpg

70mm JPG V3.jpg

70mm JPG.jpg

70mm RAW.jpg

70mm V2.ARW

70mm V3.ARW

102mm JPG.jpg

102mm RAW.jpg

125mm JPG.jpg

125mm RAW.jpg

135mm JPG.jpg

135mm RAW.jpg

200mm JPG.jpg

200mm RAW.jpg

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Guest Ebrahim Saadawi

Very well done. Not in raw = not a sensor nor lens/adapter issue.

This is most definitely a processing defect in the camera turning raw data to JPEG and Video. 

Now we just need another tester so we'd know whether to return the camera for repair warranty or if it's a global a7sii issue so you'd learn to avoid it.

 

Many a7sii owners here just wait for replies:

@jcs @AndrewReid 

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