XDCam red edging

[Guest Benjamin Pritchard]

During a recent shoot using a Sony PMW500 set to 422 50mbps MPEG2 I was looking to shoot a character in front of a completely blown out window. I used no fill as I wanted over expose the image till the entire (large) window had blown to white. I found that up to a point the image was fine until blowing the last of the detail seen through the window. A red edge appeared all around my foreground subject much like a solid red ghost image. The red had distinct boundaries rather than feathering into the shadow detail.

Has anyone come across this and how might it be controlled. Given the hectic nature of the shoot I left a bit of detail in the window and exposed to just before the red appeared so that the windows might be further blown in post. I would imagine that clipping the whites might have worked but couldn't get it working on the day.

Is this particular to the camera system used or an HD issue in general.

 

Benjamin

[Ari Davidson]

During a recent shoot using a Sony PMW500 set to 422 50mbps MPEG2 I was looking to shoot a character in front of a completely blown out window. I used no fill as I wanted over expose the image till the entire (large) window had blown to white. I found that up to a point the image was fine until blowing the last of the detail seen through the window. A red edge appeared all around my foreground subject much like a solid red ghost image. The red had distinct boundaries rather than feathering into the shadow detail.

Has anyone come across this and how might it be controlled. Given the hectic nature of the shoot I left a bit of detail in the window and exposed to just before the red appeared so that the windows might be further blown in post. I would imagine that clipping the whites might have worked but couldn't get it working on the day.

Is this particular to the camera system used or an HD issue in general.

 

Benjamin

 

Sounds like aliasing due to the bayer pattern.

Post a sample?

[Guest Benjamin Pritchard]

Here are some examples of the red edging discussed above. Test 1 is shot at f.16 and test 6 at f.1.8. the issue becomes progressively worse the more over exposed the image. Admittedly I couldn't imagine wanting to over expose more than test 1 in this case but I did before and would like to know why I can't.

[Andre Labous]

Benjamin,

I had similar problem with my PMW-500 using a Canon HJ 4.7x11 lens. It my case the chromatic aberration problem created blue lines in edges from extreme over exposure on horizontal and vertical lines. The PMW 500 has Automatic Lens Aberration Compensation. In menus make sure you have right lens selected. My problem was finally solved when I sent my lens back to canon and had latest firmware installed so that the 500 could recognize the lens thus adjusting aberration.

Hope that helps,

Andre

[Guest Benjamin Pritchard]

Here is a still from the original footage. Of particular alarm is the red line emanating from the left side of the frame. Was this similar to the blue edging seen?