Why shadow noise on scans of B+W negs?

<p>When I scan my black and white negs why do I get shadow noise? Here is what I'm wondering... on the negatives, the shadow areas have very low density. So the CCD on the scanner should receive the most exposure in the shadow areas. This should give a high signal to noise ratio. But after inverting the images, if you try to lighten the shadows too much, they can show quite a bit of noise. Is it a problem that the blacks (in the positive) are simply not finely enough represented to take too much dodging in post? I am scanning in color neg mode, 48 bit, and working on 16 bit tifs. Or perhaps it's because my scanner or the scan software is clipping the shadows?</p>

<p>What scanner and software combination are you using?</p>

<p>After thinking about it some more, I think I realize the problem in my thinking. Although the S/N ratio is initially high in the shadows (because I'm scanning a negative), when you invert the image you're left with the gain or read noise. So after you invert, you're left with high S/N in the highlights, and low S/N in the shadows. </p>

<p>I'm using an epson 3200 with epson scan. Tried vuescan and silverfast, but found for b&w negs the epsonscan scans looked better and were less noisy which was puzzling. Also experimented with multi sampling and multi exposure, but found this simply took much longer and I ended up with something that was comparable to what I got with epson scan in single pass mode.</p>

<p>Have you tried scanning at 3200 ppi and then downsampling to 2400 ppi which is closer to the real resolution of this scanner? The downsampling process can also act as a good noise reduction function.</p>

<p>It all depends on your definition of signal. In the case of the scanner, the signal is actually not the light itself, but rather the absorption of light by the silver grains. Therefore in the shadow areas, your signal is actually pretty low.<br>

And what Doug said will reduce the apparent noise as well.</p>

<p>The signal for a scanner is light.</p>

<p>Although the shadows are mostly clear, there is always some residual exposure due to light or chemical fog. Shadows should still receive some exposure, unless they represent total "blackness". You can always adjust the histogram (or Curves) to make sure the darkest areas are totally black.</p>

<p>It would help to post an example of what you are experiencing.</p>