D7100 'streaking'

Started Apr 7, 2013 | Discussions thread
mosswings
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Re: D7100 'streaking'
In reply to Jussi Mattila, Apr 7, 2013

I'd like to know more of the EXIF data.  Was A-DL on?  What lens was being used?

This result is quite strange but quite faint.  That it is barely visible at +2 in the D90 and disappears completely as you increase ISO in the D7100 suggests that the effect is occurring right at the lower limits of the D7100's dynamic range at ISO 200 - and since the D90 has less DR, as well as less resolution, you don't see it at that ISO. It almost drowns in the noise floor - the exposure (a tricky one  for autoexposure, by the way) is biased towards the bright window in both cases.

The fact that the "streaking" appears to be a simple linear translation or reflection of the extremely bright window and blinds suggests possible ghosting in the lens that you're using.  It appears to be a faster lens (f2.8), and such lenses tend to be more susceptible to such off-axis problems.  That it also appears in the D90 shot supports this hypothesis.  The sensor surface is reflective as well and can set up strange light paths inside the lens when presented with such scenes.  It would have been interesting to do a shot at a higher aperture.  With a higher aperture the lens elements are blocked from seeing any errant reflections that the wide aperture permits.

A simpler test might be to set up a specular light source against a dark background in roughly the same geometry to see if you get a ghost image on the other side.

 mosswings's gear list:mosswings's gear list
Olympus XZ-1 Nikon D90 Nikon D7100 Nikon AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR Nikon AF-S Nikkor 70-300mm f/4.5-5.6G VR +1 more
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