D7100 'streaking'

Started Apr 7, 2013 | Discussions thread
mosswings
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Re: not an issue
In reply to krikman, Apr 13, 2013

krikman wrote:


That this effect exists is curious, but we're geeky. The relevant issue is whether this makes any difference to your day-to-day shotmaking. It probably doesn't in any practical sense; all it means is that you might feel less self-assured in unusual lighting situations. All it probably means is that you want to be careful when taking high-DR shots of venetian blinds

I still can't imagine any other scene where streaking can occure. Can somebody suggest any?

So its not a Nikon/Toshiba problem but venetian blind windows problem.

It's possible that the extent of the bright zone along one or the other axis of the sensor may affect the amount of streaking observed.  If we postulate that it's the mechanism that Fuller in his paper (citation above) offers - then the ratio of the number of bright pixels to dark pixels in the direction of the streak may be important.  Remember that we saw really only the background noise level (the greenish wall) following the blinds or darker features in the window. It was the bright sections that brightened the wall, exactly as predicted by Fuller.

This offers an interesting experiment.  Begin with the shot of the window as we've seen, then mark down the exposure.  Switch to manual, and take a series of shots with a narrower and narrower slice of the window.  If we see the bright stripes on the wall fade, or fade somewhat with distance from the slice of window, that suggests we're seeing Fuller's mechanism.

Fuller proposes a few strategies for coping with this mechanism. They involve lowering the impedance of certain pixel nodes, which means higher current and therefore power dissipation; allowing certain key pixel bias nodes to settle more, which means slower operation or increased current and power dissipation; and probably a few other techniques known only to the sensor design gods.

There are several instances in which this subject situation might crop up, but they are most likely masked by other aspects of the scene. For example, if you're shooting a picture of the setting sun through a keyhole while sitting inside a closet, you'll probably see some streaking from any sensor.  But if you're shooting pictures of the setting sun on a beach somewhere, you probably won't.

Of course, much of this is purely speculation on my part, and I'm quite dangerous because I know how to read a circuit diagram but not how to design a sensor.  Still, it's a lot of fun.

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