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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D


@MatthewB wrote:

This seems to only happen when I'm shooting during the day with bright sulight and then the dark portions of the image become covered in the red grain. Does this make sense?


Yes, it does make sense.  Was this shot in sunlight?  It seems overcast.

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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

It was bright sunlight with no clouds, I was standing in the shade.

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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

[ Edited ]

@MatthewB wrote:

It was bright sunlight with no clouds, I was standing in the shade.


And, the building face is not in direct sunlight.  The sky is totally washed out.  

 

I think your shot just might have too much dynamic range.  Are you familiar with HDR captures?

 

3F26D07A-067D-453B-8BBE-7356E33615BE.jpeg

 

Here is one.  Exposing for the background was too dim to capture the foreground.  Exposing for the foreground was too bright for the background.  I took three shots -2, 0, 2 Ev.

 

 

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"Doctor told me to get out and walk, so I bought a Canon."
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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

I do know what they are but dont know how to take them in camera

 

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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

The DR of that shot is not extreme.  It is drastically underexposed.  Try the shot again with a more correct exposure and see if it helps. But first reset your camera to default settings.  Otherwise call Canon and schedule a C&C. Tell them the problem you are seeing.

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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

HDR,  "..but dont know how to take them in camera"

 

Very simple and any camera can do it. Some cameras can do it automatically. Check your manual. Essentially you take three or more shots each with a slightly different exposure.  For instance take a 1 stop underexposed, correct exposure and a 1 stop over exposed. I prefer to use Lightromm or Photoshop to merge the three, or more, shots together.

EOS 1DX and 1D Mk IV and several lenses!
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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

[ Edited ]

My guess is that 70D reads out 4 columns at a time and one of them is defect. Search for Weird stripes on 5D mark II raw. The sky has a maze pattern same as some 7D and 5D II. Green Equilibration in RawTherapee solves that.

 

Bayer pattern from your 70D below:

 

Skärmbild från 2019-09-27 10-57-49.png

DCS 3c, DCS 520, D30, D60, 1Ds, 300D, 30D, 1000D IR, 7D, 6D, 6D, M5
15-45/3.5-6.3 IS, 16-35/4 IS, 22/2, 24/1.4 II, 24-105/4 IS, 50/1.4, 85/1.8, 100/2.8, 70-200/2.8 IS II, 300/2.8 IS
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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

The DR of that shot is not extreme. It is drastically underexposed.”

It is both under and over exposed. Look at the histogram. It is saturated in both highlights and shadows.
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"Doctor told me to get out and walk, so I bought a Canon."
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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D

With Hraw it is easy to check the highlights. 0.001% clipped in green channels.

 

Capture.JPG

 

Capture1.JPG

DCS 3c, DCS 520, D30, D60, 1Ds, 300D, 30D, 1000D IR, 7D, 6D, 6D, M5
15-45/3.5-6.3 IS, 16-35/4 IS, 22/2, 24/1.4 II, 24-105/4 IS, 50/1.4, 85/1.8, 100/2.8, 70-200/2.8 IS II, 300/2.8 IS
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Re: Red Grain in the Under Exposed portions of the Image. Canon 70D


@Peter wrote:

With Hraw it is easy to check the highlights. 0.001% clipped in green channels.

 

 


I think you are correct.  I took a closer look at the histogram, and the highlights are not saturated.

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"Doctor told me to get out and walk, so I bought a Canon."
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