Lightroom/ACR RAW conversion problem - Canon 600D

[Sammy Yousef]

I'm a long time Nikon shooter who got a Canon 600D for Christmas. I've never had issues with conversion of Nikon RAW files in Lightroom but I'm seeing strange behaviour with the Canon RAW conversions under extreme circumstances.

Excuse the picture itself which is rubbish but this is the one in this sequence that highlights the problem best. Shot in a rush in a wind storm on a consumer tripod in a rush as it was about to rain. This is not a one off - I see these blue channel artifacts with the entire sequence of shots.

100% crop view. On the left out of camera JPG. On the right RAW file. Both imported to Lightroom 5. (I tried updating to 5.7 from 5.5 with no change) with camera calibration set to Adobe Standard. It looks like Lightroom is blowing out the blue channel.



If I choose one of the profiles that emulate Canon's in camera picture styles, I end up with Magenta blown out instead. Here it is with picture style Standard chosen on he right.



Is anyone able to tell me what's happening here? Is this a known issue? Is there a known solution? As it stands I don't trust Lightroom's RAW conversion.

DPP does not have any such issues and the conversion is fine with it.

Here is the metadata for the shot:
Aperture: f/3.5
Shutter speed: 30 sec
ISO: 100
Lens: 18-55 IS kit lens
Focal length: 18mm
Flash: Did not fire

Thanks for looking.

--

Sammy.
My forum postings reflect my own opinions and not those of my employer. I'm not employed in the photo business.

 

[Sailor Blue]

This is more likely related to the camera and how its Auto Exposure works than to Lightroom.

Copy the JPG and RAW images back onto your camera's memory card and put the card back in the camera. Check the three histograms of the image, you might just see the blue channel is blown out in the blue channel histogram. Now turn on the camera's Highlight Alert and look at the image full sized without the histograms. I'll bet you see the blue lights blinking.

Every camera and every camera sensor has its foibles. Some are more sensitive to one color than another. With Canon it is usually the red channel that blows out first. Sometimes a single color blowing out won't show up in the Luminosity Histogram or with the Highlight Alert so to be safe you need to check the three individual RGB histograms.

 

[Sammy Yousef]

Thanks for your response.

It still doesn't explain why Lightroom changes which colour is blown if you apply camera calibration. It really does seem to have more to do with ACR's intepretation of the data.

 

[Sailor Blue]

Thanks for your response.

It still doesn't explain why Lightroom changes which colour is blown if you apply camera calibration. It really does seem to have more to do with ACR's intepretation of the data.

Different camera profiles change things like exposure, saturation(s), and contrast to try and emulate the camera profile settings. It doesn't surprise me at all that colors that are nearly saturated become saturated and change the color of the blown out lights. The same thing might have happened if you changed the in-camera profile to a different one.