From: Arthur Wood <arthurwood@bimmerfest.com>
Subject: Re: Is there an easy way to stop this light scatter ghosting in all my photos & videos of engine valves?
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From: Arthur Wood <arthurwood@bimmerfest.com>
Newsgroups: rec.photo.digital,rec.video.desktop
Subject: Re: Is there an easy way to stop this light scatter ghosting in all my photos & videos of engine valves?
Date: Fri, 15 Dec 2017 06:18:42 -0000 (UTC)
Organization: Mixmin
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PeterN wrote:

>  I think that your answer is a good response to a real problem. 
> Some here may have encountered it and you provided an answer that would 
> help them.

I see the solution is a "diffuser" but what's the "problem".
What I mean by that is why does the light look like it's raining?

For whatever reason, it's like "sleet" at a 45 degree angle.
Where is all that "sleet" of light coming from?

And why always a 45-degree angle?
I assumed that some "physics" principle is being invoked.

No matter how I held the camera, I still got a 45-degree "sleet" of light.

Take this one example from far away:
https://www.turboimagehost.com/p/36857795/engine_bay4.jpg.html

Compared with this at 90 degrees:
https://www.turboimagehost.com/p/36857797/engine_bay6.jpg.html

Compared with this at a closeup:
https://www.turboimagehost.com/p/36857801/engine_bay10.jpg.html

All have this "sleet" of light at the same angle.

Why the 45-degree "sleet" angle in /all/ the photos?

I realize the /solution/ is a diffuser but what's the physics problem?
Is there a physics principle that causes the always 45 degree sleet?