Help: red/magenta circle on Sony A7III pictures

[Deki Majstor]

Hi all,

I couldn't find a similar post, that's why I decided to make a new one.

Some of my pictures have a red/magenta "circle" / artifact. It doesn't happen all the time and I couldn't figure out what the cause of it is. It happens in different lighting conditions, indoors (artificial light) and outdoors (full sunlight). The circle changes form and color depending on lighting. Lens correction/profile corrections in LR didn't help.

All the attached shots were in RAW with an aperture of f/2.8 with different shutter speeds and different focal lengths on the same setup: Sony A7III and Tamron 28-75 2.8.

e-front curtain shutter - off

The first picture is an extreme example and you can clearly see it. I marked it in the second and third picture. I shoot a lot at f/2.8 with the same setup for my professional work indoors, outdoors with and without flash and the problem is not consistent. It doesn't happen a lot.

Any help would be appreciated. Thank you!




indoor shot with artificial light.




outdoor, full sunlight


I removed a person from this picture. Focus on the bottom and upper half of the picture where the red/magenta circle is clearly visible.

 

[jmbillings]

Filters on the lens?

 

[dv9973]

Not enough info about processing.
Try without camera shading compensation.

 

[No account anymore]

First of all: Stop down the lens a few stops.

Second: Don't apply in-camera lens correction and then push files, especially with zoom lenses where strong vigneting. This correction affects jpg and cRAW, but not uncompressed raw.

 

[JimKasson]

First of all: Stop down the lens a few stops.

Second: Don't apply in-camera lens correction and then push files, especially with zoom lenses where strong vigneting. This correction affects jpg and cRAW, but not uncompressed raw.

WRT the last sentence above, the last time I looked, which was more than year ago, there were some a7x lens corrections that affected the raw data, and, in the case of lenses like the 24-105, produced radial color shifts.

Has that changed?

Jim

 

[Deki Majstor]

Thanks to everybody who replied!

To answer some of the questions:

- no filters used

- post processing info: I pushed the exposure 1-2 stops on the 1st and 3rd shot. Not much else done.

I still don't know what causes this.

First I thought it's because of increasing exposures too much in post, but this doesn't make sense because that would mean that it should happen all the time - which it doesn't. Then I thought it's because of high shutter speed coupled with low f-stop number, which is debunked by the first picture (and a lot of other pictures I have) which has a low shutter speed and the worst "red-circle effect".

I have to do some proper testing myself in different lighting conditions and with different settings to find out what causes this. I'll also try out what one person suggested to turn off "shading" under lens compensation in-camera, but I thought this only affects JPG's anyways. So I'll test that out as well.

 

[Paul Barnard]

I have to do some proper testing myself in different lighting conditions and with different settings to find out what causes this. I'll also try out what one person suggested to turn off "shading" under lens compensation in-camera, but I thought this only affects JPG's anyways. So I'll test that out as well.

It you turn off the shading it will go away. The fact that it impacts RAW has resulted in several very big threads in this forum. If you want the full back ground do a search for shading compensation and settle in for a good read.

 

[AZheaven]

According to the exif data your shutter speed was at 1/4000 sec. I have noticed the same thing in your photo when I shot at the speed using Shutter Priority. But I shoot mostly Aperture anyway. Don't have a need for Shutter just yet.

 

[Tristimulus]

In camera auto vignetting correction cause the red and magenta circle.

The vignetting correction is rudimentary and that is amazing given how sophisticated the image processing is generally done in Sony cameras (seems more like a glitch Sony has not worked over). The original A7 is worse in this regard.

The discolored color artefacts get more visible when shooting in overcast winter weather, in low contrast twilight, and in fog. Use my cameras a lot in low contrast light so this issue is simply too well known here. Happily most images are not affected.

Seems like Sony has a way to go when it comes to some of the more subtle parts of the in camera image processing train.

Shoot JPG in low contrast light and stretch the images - viola, colorful artefacts appear!

Use lenses like the Sony 4/24-105 or 1.8/35 and the issue gets worse.

This is a good reason to become a die hard RAW shooter (was not, am now).

 

[sharkmelley]

This issue has been discussed many times previously but unfortunately the discussions tended to generate more heat than light:

The effect of in-camera Lens Compensation and more ...

Sony A7III Posterization and Colored Banding

Sony A7xxx Posterization and Colored Banding (Part 2)

Sony A7xxx Posterization and Colored Banding (Part 3)

Sony A7xxx Posterization and Colored Banding (Part 4)

The problem can be reduced by switching off the lens shading correction in the camera menu but even so, some kind of correction is still applied to the raw data which causes those coloured rings to appear in shadow areas during heavy post-processing.

Mark

 

[reyvis]

I thought i would put my two penny's worth in! As i have had a lot of these magenta rings. The above is what I call a reject photo before I would post process.

I do a fair bit of astro with a sony 24mm gm 1.4. I was getting that magenta ring. Usually i stack from 10 images up to over 100. With 10-20 images the ring was present but usually disappears when the stack is 40 images or more due to the advantage of stacking re noise etc. Having read many of the theads about this problem. i did my own tests.

The above pic is an example. THERE is no Sony in lens compensation, it is a stretched no compression raw and linear stacking with no pre- alteration. each image is10seconds/iso 1600 and f1.4 and uploaded here as a jpeg. No filter etc.The Tiff outputs are the same .

So what is the reason why this happens. the solution points to one thing for me. If I use F2 instead of F1.4 the ring goes away immediately. if i use f1.4, then f1.6, then f1.8 the ring reduces by a linear amount.

I assume it is because the lens has very strong vignetting at f1.4. Only happens when i use the lens for astro landscapes. Ie long exposures. It may be lens specific and related to design parameters or some other combination.

Long exposure night photography seems to tax these sensor / lens combinations to their limits. Or maybe i am just a bad photographer.



--
Sony A7 & A7r3 with 24 f1.4 , 24-105 f4 and 16-35 f4 ( have had the 28-70, 24-70 and 70-300)

canterbury

Explore canterbury’s 936 photos on Flickr!

www.flickr.com

 

[JimKasson]

I thought i would put my two penny's worth in! As i have had a lot of these magenta rings. The above is what I call a reject photo before I would post process.

I do a fair bit of astro with a sony 24mm gm 1.4. I was getting that magenta ring. Usually i stack from 10 images up to over 100. With 10-20 images the ring was present but usually disappears when the stack is 40 images or more due to the advantage of stacking re noise etc. Having read many of the theads about this problem. i did my own tests.

The above pic is an example. THERE is no Sony in lens compensation, it is a stretched no compression raw and linear stacking with no pre- alteration.

What did you use to demosaic the images?

each image is10seconds/iso 1600 and f1.4 and uploaded here as a jpeg. No filter etc.The Tiff outputs are the same .

So what is the reason why this happens. the solution points to one thing for me. If I use F2 instead of F1.4 the ring goes away immediately. if i use f1.4, then f1.6, then f1.8 the ring reduces by a linear amount.

I assume it is because the lens has very strong vignetting at f1.4. Only happens when i use the lens for astro landscapes. Ie long exposures. It may be lens specific and related to design parameters or some other combination.

Long exposure night photography seems to tax these sensor / lens combinations to their limits. Or maybe i am just a bad photographer.

--

the last word the last word - Photography meets digital computer technology. Photography wins -- most of the time.

Photography meets digital computer technology. Photography wins -- most of the time.

blog.kasson.com

 

[Tristimulus]

First of all: Stop down the lens a few stops.

Second: Don't apply in-camera lens correction and then push files, especially with zoom lenses where strong vigneting. This correction affects jpg and cRAW, but not uncompressed raw.

WRT the last sentence above, the last time I looked, which was more than year ago, there were some a7x lens corrections that affected the raw data, and, in the case of lenses like the 24-105, produced radial color shifts.

Has that changed?

The A7II i is better in this regard (radial color shifts) than the original A7.

But the issue still remain. My two worst lenses in this regard is the 4/24-105mm G and the 1.8/35mm lens - stop down and things improve but never dissapear fully.

Images taken in fog and cloudy snowy weather are visually affected. Low contrast and evenly illuminated areas (the sky) are most affected.

The astro image above shows clearly that Sony users are in for more than one challenge when trying to get the most out of the night sky. Colors vary with scene intensity which is a very bad thing (does not affect ordinary photos except when using lenses which vignette heavily in low light underexposed scenes).

Forget Sony for more serious deep sky astrophoto. Especially in light polluted areas.

Works wonders in twilight before astronomical twilight end.

Given the mostly very sophisticated image processing done in Sony cameras the rudimentary handling of vignetting (radial color shifts) and colors varying with scene intensity is a bit puzzling - should ideally be fixed long ago...

 

[reyvis]

I do not think i can give anything of use to you Jim 'K', who knows more in your little finger than I will ever know ! But for the record. I usually stack the unaltered raws in Sequator and stretch with RNC . After that it depends upon the output tiff what i do next. I live in light polluted areas and the best bortle level i can get is probably 4. light domes on every horizon. i never use flats, dark frames etc. I was hopeful that f1.4 was ok for astro. It is, if i do a large enough stack. I should get a tracker!

I adopted the Sony A7 series when it first came out. i like the system very much. Astro nightscapes are always a challenge when sitting in the middle of a dark field all by yourself, cold, windy and after midnight when i should be tucked up in bed like more sane people. Then i see the ISS go by in the sky and think I wish i was up there!

 

[A7iiishooter9]

Oh my God I’ve been trying to find an article on this for months. I’ve yet to read the whole thread anyway, this problem is worse in darker areas. For example shoot a dark horizon with certain amount of light. E whole thing have concentric purple and green circular stuff like these and it looks really bad. I also tried out my very old Sony a55, it did not happen there.

 

[No account anymore]

Oh my God I’ve been trying to find an article on this for months. I’ve yet to read the whole thread anyway, this problem is worse in darker areas. For example shoot a dark horizon with certain amount of light. E whole thing have concentric purple and green circular stuff like these and it looks really bad. I also tried out my very old Sony a55, it did not happen there.

Turn off in-camera lens corrections. Also nte that tis defect is most pronounced when using bright apertures, since it is probably related to on-sensor vignette correction.

If this doesn't do the trick, try using uncompressed raw.

 

[akjackson009]

Mark,



I've tried everything to reduce those magenta circles in my Sony uncompressed RAW files including turning off all the settings suggested. I'm noticing the rings in very low contrast areas such as clouds even without post processing in the native RAW files. I've replicated the issue in multiple Sony a7r III bodies and one a7r IV bodies and switched to Nikon Z7 II'S. I know this is an old thread, but any update and maybe a possible solution? I miss my Loxia 21mm!



Thanks,
Concerned ex-Sony shooter