Purple haze with electronic shutter in Lumix GX85

[purplehazeissuer]

I recently bought a used Lumix GX80/GX85 and shot some night images with it. I noticed some of the photos have this clear purple/red haze at the top edge of the images. I tested further by shooting with lens cover on at high ISOs and noticed that the haze seems to only appear on electronic shutter, and is absent with mechanical shutter.

I have tried different lenses and the haze happens with all of them. I've cleaned the sensor and done pixel refresh. I've tried taking photos with different orientations and while panning up and down, but didn't notice any clear pattern when the haze happens, other than the shutter type. Sometimes with electronic shutter the haze is stronger, sometimes fainter. Visible in both RAW and JPEGs.

Here are two photos, first one with electronic shutter and the second with manual. The noise profile of the manual photo is not pretty either, but at least with normal photos it blends in nicely whereas with the purple haze at the edge is clearly visible in the edited images taken with electronic shutter.


Electronic shutter, haze clearly visible at the top.


Mechanical shutter, no edge haze.

Any idea what might cause this?

 

[daddyo]

N/T

--
Blessings,
Greg
http://www.pbase.com/daddyo

 

[grsnovi]

Any idea what might cause this?

ISO 25600

 

[ChrisFB]

Seems odd, but I notice you’re at 25600 iso - bit too much for the GX85.

Do you have normal samples, low light, at say, max 6400? Still an issue then?

 

[jalywol]

Does it do it at normal settings?

-J

 

[valsan]

Does it do it at normal settings?

-J

no, but then that wouldn't be clickbait

 

[Trolleyman]

Any idea what might cause this?

ISO 25600

Jimi Hendrix?

 

[JosephScha]

I have a G9. I must say: I have never shot a picture at ISO 25,600. Not ever.

Do you know what raising the ISO does? It lowers the code that corresponds to white. Let's assume the ADC can read out up to 10 bits at base ISO (I don't know if this is true):

ISO 200: 0 to 1023

ISO 400: 0 to 511 - white is code 511

ISO 800: 0 to 255 - white is 255

ISO 1600: 0 to 127 - white is 127

ISO 3200: 0 to 63 - white is 63

ISO 6400: 0 to 31 - white is code 32

ISO 12,800: 0 to 15 - white is code 15

ISO 25,600: 0 to 7 - white is code 7

Now, how much noise do we think might occur in the readout? Perhaps 3 codes?

3 codes doesn't do a thing at ISO 200 or ISO 400. But at ISO 25,600 3 codes of noise is almost half way to white. Of course you see it.

You didn't mention if you had the lens cap on, and were in a dark room. Even if the lens cap was on, ISO 25,600 is unreasonably sensitive. Any light in the room that snuck around the lens cap could be what you see.

Can I ask you to PLEASE repeat this test at ISO 1600? Or even ISO 3200? ISOs you are more likely to use. I'm willing to bet you won't see anything.

--
js

 

[Gary from Seattle]

[No message]

 

[Dino Anderson]

This is called amp glow. It's basically a form of readout noise. Just don't shoot that high ISO. This camera is not meant for that.

 

[Bassam Guy]

 

[Bassam Guy]

 

[Stu3133]

Strange.... I cant see the black cat either!!

 

[alcelc]

Due to the shutter shock concern (14-140) of GX85, I use e-shutter all of the time. Never realize the same problem in last 8 years shooting with this little camera.

The following was a snapshot from my old travelling album taken by GX85 at ISO3200 (ther current ISO ceiling set on GX85) using e-shutter always in a dark background. It is a SOOC JPG (on Vivid and NR=0) to show how GX85 would perform. Under 1:1 (my usual ruler to i.d. a keeper) I trust you should not find the purple haze as claimed.





I expect a few simple editing in PP might eliminate the noise and remove the tiny softness...

--
Albert
** Please forgive my typo error.
** Please feel free to download my image and edit it as you like **

 

[agott123]

nt..

 

[purplehazeissuer]

Those values were to highlight the issue. It does happen with normal values too. Here is 1/250 sec, f/1.8 ISO 1600:

 

[purplehazeissuer]

It does happen with lower light. I shoot at max 1600 and it happens there. The 25600 ISO and f22 photos were just to showcase the issue since those parameters exaggerate the haze.

Here is a 1600 f1.8 photo, you can see the haze at the top.

 

[purplehazeissuer]

Thanks, googling amp glow shows similar issues, some forums were also discussing about light leak. The haze appears even at ISO 1600, which shouldn't be too high.

 

[purplehazeissuer]

Thanks, I know how ISO works and normally I shoot max 1600. That shouldn't bee too high, but I can still see the haze there.

Here is one ISO 1600 photo with the haze visible:

 

[Markusweld]

Any idea what might cause this?

ISO 25600

Jimi Hendrix?

I was going to say Prince, but not sure if Purple rain & Purple haze have anything to do with each other