What's this??!! ( circular ring artifacts )

Started 6 months ago | Discussions
Ari Aikomus
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What's this??!! ( circular ring artifacts )
6 months ago

http://diglloyd.com/blog/2014/20140223_3-SonyA7R-circular-ring-artifacts.html

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eths
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Re: What's this??!! ( circular ring artifacts )
In reply to Ari Aikomus, 6 months ago

Interesting if true, but the tone of the article kind of disqualifies it, IMHO.

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Ari Aikomus
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Re: What's this??!! ( circular ring artifacts )
In reply to eths, 6 months ago

eths wrote:

Interesting if true, but the tone of the article kind of disqualifies it, IMHO.

Yep, I've been trying to find more information about that, rather that how "big" problem this is, if real at all - but without success.

...I wonder a little bit how much people try to find faults about A7 models

Anyway, IF this is a real issue - of course, it need to bring up and discuss it clear.

Ari

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sassenach74
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Re: What's this??!! ( circular ring artifacts )
In reply to Ari Aikomus, 6 months ago

Did he not show the image he's talking about?!

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Neil.

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wictred
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Re: What's this??!! ( circular ring artifacts )
In reply to Ari Aikomus, 6 months ago

Ari Aikomus wrote:

http://diglloyd.com/blog/2014/20140223_3-SonyA7R-circular-ring-artifacts.html

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can't see any examples there.

the link to the review ("See the review of the Sony A7 / A7R") leads a page with a couple links, the only one that sounds relevant ("Sony A7R: 'Shading Comp' Bug?") to a login mask / error message:

"Login failed

Access to this content is by subscription:"

Obviously it can't be a big deal.

I assume we're talking about the same circular banding that was also visible on all previous NEX models when pushing RAWs by at least 3EV in PP, right? (which can be removed by turning off lens corrections - they DO affect RAW)

Samsung have the same (non)-issue with their mirrorless cameras.

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wictred
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Re: What's this??!! ( circular ring artifacts )
In reply to wictred, 6 months ago

OK after reading the Ricoh related article it turns out that we're indeed talking about the vignetting/banding that is visible when pushing exposure in PP but the site claims that they are also visible in bright lighting on the A7R.

I think "pics or it didn't happen" is more than appropriate in this case

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mbietenholz
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Re: What's this??!! ( circular ring artifacts )
In reply to wictred, 6 months ago

wictred wrote:

I assume we're talking about the same circular banding that was also visible on all previous NEX models when pushing RAWs by at least 3EV in PP, right? (which can be removed by turning off lens corrections - they DO affect RAW)

On my NEX-6, the lens-corrections do NOT affect the RAW.  The lens corrections for the kit lens (vignetting, distortion and chromatic aberration) are pretty obvious, and if I open the file in RAWtherapee, I can turn any of these corrections on or off at will.

It is of course possible that Sony changed this on later models, but there has been much confusion on this issue because of RAW converters that silently make the corrections for you if the EXIF data indicates that they were set in the camera. In some cases (Sony IDC but I think it isn't the only offender) the RAW converters don't even give you the option of turning the corrections off.

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wictred
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Re: What's this??!! ( circular ring artifacts )
In reply to mbietenholz, 6 months ago

mbietenholz wrote:

On my NEX-6, the lens-corrections do NOT affect the RAW. The lens corrections for the kit lens (vignetting, distortion and chromatic aberration) are pretty obvious, and if I open the file in RAWtherapee, I can turn any of these corrections on or off at will.

Oh but they do.

try the following:

- take a severely underexposed shot in RAW.

- add at least 3 EV in PP (might need up to 5)

try the same with and without vignetting correction.

see if there is a difference.

with lens correction activated, you should see a circular banding effect. the RAW does not have the vignetting correction applied of course, however the circular banding effect is there...

This is the same kind of circular banding that is described in the Ricoh related article linked in the original post.

I just took two examples with the NEX-6, this is how it looks after pushing 5(!) EV in PP

both are shot in RAW, imported into LR, exposure changed by +5 EV, no additional changes.

vignetting correction on

vignetting correction off

This is completely irrelevant in normal usage. The original image is almost pitch black.

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wictred
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Re: What's this??!! ( circular ring artifacts )
In reply to wictred, 6 months ago

The same can also be seen in Samsung cameras and apparently also Ricoh.

With Samsung cameras you can't turn it off. Changing the lens correction settings does not remove the banding, but it goes away if you use manual lenses.

Maybe this is some minor "offset correction" (applied to the RAW) to cope with corner issues caused by the small flange focal distance and which only becomes visible ("amplified") when pushing shadows.

For some reason Sony have deactivated this "correction" (or whatever it is) when you disable lens vignetting correction altogether, which is actually a good thing.

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Mel Snyder
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Re: What's this??!! ( circular ring artifacts )
In reply to eths, 6 months ago

eths wrote:

Interesting if true, but the tone of the article kind of disqualifies it, IMHO.

I agree re tone. I find a lot of articles with the tone, "For what offense are we hanging him today?"

In the pharmaceutical industry, companies can test a drug in hundreds - even thousands - of patients, and study the blood tests and clinical effects in them all. Cameras simply are not developed and tested that way.

HOWEVER - despite all the testing of new drugs, we regularly discover side effects and adverse reactions never seen in the clinical trials, once the drug has been prescribed to hundreds of thousands, even millions of patients. I've seen drugs that looked perfect and safe in clinical trials get withdrawn completely for defects not appreciated until hugely used.

New cameras are more likely to have issues than new drugs. I bought my A7 prepared to accept it was very much a V1.0 camera. And like new drugs, issues could arise after it was in the hands of tens of thousands of users - issues Sony didn't encounter. That's the penalty of buying early.

Look at the photo below. Look at the sky. This was shot with the Ultra-Wide Adapter on the Sony SEL16F28. No filter. I did not PP the sky or vignette it. My only explanation is the altitude: 12,500 feet above sea level, subfreezing ambient temperature. Light at that altitude can be VERY polarized, and lens curvature could combine for the explanation. It never did anything like this at low altitudes.

I'll bet Antarctica has similar light or worse. rest assured Sony didn't send a team there to test the A7 and its lenses.

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mbietenholz
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Re: What's this??!! ( circular ring artifacts )
In reply to wictred, 6 months ago

wictred wrote:

mbietenholz wrote:

On my NEX-6, the lens-corrections do NOT affect the RAW. The lens corrections for the kit lens (vignetting, distortion and chromatic aberration) are pretty obvious, and if I open the file in RAWtherapee, I can turn any of these corrections on or off at will.

Oh but they do.

try the following:

- take a severely underexposed shot in RAW.

- add at least 3 EV in PP (might need up to 5)

try the same with and without vignetting correction.

see if there is a difference.

with lens correction activated, you should see a circular banding effect. the RAW does not have the vignetting correction applied of course, however the circular banding effect is there...

This is the same kind of circular banding that is described in the Ricoh related article linked in the original post.

I just took two examples with the NEX-6, this is how it looks after pushing 5(!) EV in PP

both are shot in RAW, imported into LR, exposure changed by +5 EV, no additional changes.

vignetting correction on

vignetting correction off

This is completely irrelevant in normal usage. The original image is almost pitch black.

I'll try this later when I get a chance.   I don't get it - turning the vignetting correction on in the camera does *not* cause the vignetting correction to be baked into the RAW data, but *does* cause some other subtle change in the RAW data that produces banding at very low light levels?

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wictred
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Re: What's this??!! ( circular ring artifacts )
In reply to mbietenholz, 6 months ago

mbietenholz wrote:

I'll try this later when I get a chance. I don't get it - turning the vignetting correction on in the camera does *not* cause the vignetting correction to be baked into the RAW data, but *does* cause some other subtle change in the RAW data that produces banding at very low light levels?

Exactly.

But it is only a very very small effect ...

However when it is the lower bits of the RAW it will become visible when you push the exposure afterwards.

The shadows don't contain that much detail, and if you "amplify" the result in PP, small differences become visible. Just like shadow noise becomes visible the same way.

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walnorth
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Re: What's this??!! ( circular ring artifacts )
In reply to Ari Aikomus, 6 months ago

Is this the same guy who says that the NEX 7 "is just a toy" and not a camera? And uses "confluence" in the title of many of his photos? His finding a "problem" to dismiss the camera is a foregone conclusion. I'm just surprised he doesn't say that it makes waffles in your camera bag during a full moon.

Yet so many people are out there making great photos with a NEX 7 or Alpha 7/r. All of us must be deluded.

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mbietenholz
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Re: What's this??!! ( circular ring artifacts )
In reply to wictred, 6 months ago

wictred wrote:

mbietenholz wrote:

I'll try this later when I get a chance. I don't get it - turning the vignetting correction on in the camera does *not* cause the vignetting correction to be baked into the RAW data, but *does* cause some other subtle change in the RAW data that produces banding at very low light levels?

Exactly.

But it is only a very very small effect ...

However when it is the lower bits of the RAW it will become visible when you push the exposure afterwards.

The shadows don't contain that much detail, and if you "amplify" the result in PP, small differences become visible. Just like shadow noise becomes visible the same way.

I stand corrected: you are indeed right wictred - the setting of vignetting-corrections (Lens Comp: shading) *does* affect the RAW data for the NEX-6, at least for the 16-50 kit lens (SELP1650). I just did some test shots, and it looks like turning this correction on in camera causes a partial correction for vignetting to be made to be baked into the RAW data, with the side effect that banding can be produced at very low light-levels.

My guess is the banding is likely the result of doing integer math when doing the in-camera vignetting correction.  It seems unlikely to be due to the raw compression used because that would affect the image whether the in-camera correction was enabled or not.  Also, the raw-compression is pretty local so I don't think it would produce this kind of effect

As Wictred said, the banding only shows up at very severe underexposure, like -4 or more stops, so the banding is probably a pretty minor issue in real life.  I will continue to leave the vignetting correction enabled in-camera - that way the OOC jpegs will be good to go for those shots where I don't want to bother with raw conversions.  If, however, you plan on digging way down into the noise, you might want to disable this correction in the camera (astrophotography is one possible case where you may to disable it).

It may also not affect all lenses -  the SELP1650 kit-lens has fairly severe vignetting issues, so the correction for vignetting is fairly strong (especially if you *don't* correct for the lens distortion).

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Keit ll
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Re: What's this??!! ( circular ring artifacts )
In reply to mbietenholz, 6 months ago

Hasn't this issue been aired elsewhere & shown to be a result of light leaking into the camera from gaps in the lens mount ? The circular bands vary depending on the direction & colour of the light penetrating into the camera.

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mbietenholz
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Re: What's this??!! ( circular ring artifacts )
In reply to Keit ll, 6 months ago

Keit ll wrote:

Hasn't this issue been aired elsewhere & shown to be a result of light leaking into the camera from gaps in the lens mount ? The circular bands vary depending on the direction & colour of the light penetrating into the camera.

I don't think so - whether or not any light will leak into the camera isn't going to depend on the setting of the "Lens Comp: shading".  I did a couple of test shots and it was pretty clear that you got the banding then the "Lens Comp: shading" was enabled and did not get banding when it was disabled.

Lens leaking into your camera may of course *also* cause banding under some circumstances.

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Keit ll
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Re: What's this??!! ( circular ring artifacts )
In reply to mbietenholz, 6 months ago

mbietenholz wrote:

Keit ll wrote:

Hasn't this issue been aired elsewhere & shown to be a result of light leaking into the camera from gaps in the lens mount ? The circular bands vary depending on the direction & colour of the light penetrating into the camera.

I don't think so - whether or not any light will leak into the camera isn't going to depend on the setting of the "Lens Comp: shading". I did a couple of test shots and it was pretty clear that you got the banding then the "Lens Comp: shading" was enabled and did not get banding when it was disabled.

Lens leaking into your camera may of course *also* cause banding under some circumstances.

I didn't reference the use of Lens Comp:shading. Use google to search for 'light leaks on Sony 7/7r'. For some reason this issue has disappeared from recent comments on these cameras

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LeicaBOSS
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Re: What's this??!! ( circular ring artifacts )
In reply to Ari Aikomus, 6 months ago

I wrote about this in December. It really appears to be specific to the FE 35mm f/2.8. I haven't really seen it with the other lenses (and I've looked). You do have to work pretty hard to see it. Overall, Lloyd is a cranky blowhard but this appears to be real.

http://www.leica-boss.com/2013/12/the-problem-with-sonys-zeiss-fe-sonnar-t-fe-35mm-f2-8-za-sel35f28z/

Below is a saturation enhanced image from the FE 35mm f/2.8 - of a white balance expodisc illuminated with a diffused flash

This is a bad as it gets in real images:

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