noise / moire pattern 5diii long exposure low iso

[edawg]

I am having an issue with some sort of green/magenta noise pattern or moire with my 5d III. Has anyone else noticed this?

I have noticed it at low ISOs with long exposures of particularly blank surfaces lacking detail: shadows, water, etc.

How can I avoid this?

Here is the original:

And with curves adjusted so you can see the issue more clearly:

Turning off Auto Lighting Optimizer actually makes it worse. Images processed in DPP.

 

[edawg]

EXIF data:

File Name EDG_4054_1.CR2
Camera Model Canon EOS 5D Mark III
Firmware Firmware Version 1.0.7
Shooting Date/Time 6/1/2012 10:15:42 PM
Author Ed Graham
Owner's Name
Shooting Mode Bulb
Tv( Shutter Speed ) 150.4
Av( Aperture Value ) 11.0
Metering Mode Evaluative Metering
ISO Speed 200
Auto ISO Speed OFF
Lens EF17-40mm f/4L USM
Focal Length 17.0mm
Image Size 5760x3840
Image Quality RAW
Flash Off
FE lock OFF
White Balance Mode Auto
AF Mode Manual focusing
Picture Style Auto
Sharpness 3
Contrast 0
Saturation 0
Color tone 0
Color Space sRGB
Long exposure noise reduction Disable
High ISO speed noise reduction Standard
Highlight tone priority Disable
Auto Lighting Optimizer Standard
Peripheral illumination correction Disable
Chromatic aberration correction Enable
Dust Delete Data No
File Size 23176KB
Drive Mode Single shooting
Live View Shooting OFF

 

[jrista]

That is not moire, nor is it noise...its posterization. This kind of thing is often the result of image processing and compression, and can be seen frequently in JPEG images less than around 90 quality that have areas of smooth gradient (like a sky.)

I can't be sure what causes that, however I do believe I remember seeing some threads in the past about similar problems with the 5D II as well. I noticed that you have High ISO speed NR enabled... You might want to disable that. You might also want to disable the CA correction. Those are all post-processing effects, and they may be affecting the saved image. I know the Image Quality EXIF value says "RAW", however I am suspicious it might actually be a native-size form of mRAW (a form of YCC encoding, and definitely not an actual RAW format.) To actually apply aberration, peripheral illumination correction, and noise reduction, the output image couldn't be in a true RAW format, and if the data is encoded in some form, then that could be the source of the posterization.