From: Jeff <j@donotspam.me>
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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Subject: Re: Is there an easy way to stop this light scatter ghosting in all my photos & videos of engine valves?
From: Jeff <j@donotspam.me>
References: <p0ua03$mcf$1@news.mixmin.net> <tot53d9cdaq17no7um1bjlgn35pk7olbop@4ax.com> <p0vpol$67e$1@news.mixmin.net>
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Arthur Wood<arthurwood@bimmerfest.com> wrote in
news:p0vpol$67e$1@news.mixmin.net: 

> Eric Stevens wrote:
> 
>> I think you mean cams rather than valves.
>> 
>> It looks to me as though the highlighted parts give rise to a strak of
>> light at an angle to the frame of the image. In some of the shots
>> (e.g. bay 10) streaks can be seen emenating from highlights other than
>> the cams. I suspect the problem may be due to a smear on the camera
>> lens. I suggest you try it with another camera.
> 
> You are correct in noticing that all the streaks of light are at the
> same 45 degree angle no matter how the camera is held.
> 
> That's why I think it may be some "physics" principle involved.
> 
> There are many other photos taken with the same camera but under
> daylight lighting where these streaks do not happen so it's not the
> camera. 
> 
> Some of those photos are here.
> http://www.bimmerfest.com/forums/showthread.php?t=1181089
> 
> And here:
> http://www.bimmerfest.com/forums/showthread.php?t=1181289
> 
> So it's not the camera or the lens except under those lighting
> conditions. 
> 
> I was assuming there is something weird in the physics of the lighting
> that causes those sleet like streaks always at 45 degree angles and far
> from being a mere reflection.

The "physics" are because the smudge on the lens is at a 45 degree angle.