V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 78
Nikon has done a good job of suppressing such patterns,
especially when you turn on the various noise reduction
schemes the camera supports. On the other hand, if you turn
off noise reduction, underexpose, and use a high ISO value,
you very well may see some patterning to the noise
production in your shots. In general, however, proper
exposure and camera settings should help you avoid that.
Also, make sure your D300 has the latest firmware, as Nikon
changed an internal routine that was triggering visible patterns
on long exposures.
Before I wrap up this section on noise, I need to differentiate
between sensor noise and image noise. So far in this section
I’ve talked about noise that is generated by the sensor and the
accompanying signal capture electronics. Once a final image
is produced by the imaging ASIC
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in the camera and we have
RGB pixels to look at, we talk about noise differently.
Specifically, we refer to two types of noise we can
see
in the
final image data: luminance noise and chroma noise.
Luminance noise is essentially
brightness
changes from pixel
to pixel that are incorrect. If you see a pebbled texture of
same colored pixels in a broad single tonal area, such as sky,
you’re seeing luminance noise. This often looks similar to film
grain. If you see pixels of color (typically red, blue, or green)
where they aren’t supposed to be, you’re seeing chroma
noise. This type of noise is decidedly un-film like.
Luminance and chroma noise are how the noise from the
underlying sensor and supporting electronics end up
appearing in the final image. The D300 is aggressive at trying
to control chroma noise, but less so at controlling luminance
noise. You have some ability to control this aggression by
using the
High ISO NR
settings in the SHOOTING menu.
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Application-Specific Integrated Circuit
