V700 does (unwanted) posterization

[bernard_lazareff]

<p>Even though its raison d'être is MF, I use my V700 occasionally to do a quick scan of a 35mm roll, including b/w. When looking at the scan result for the attached frame, I had an impression of posterization in the gradient, in the upper part of the frame.</p><div></div>

[bernard_lazareff]

<p>To confirm or disprove that impression, I created a histogram of the region extending across the width of the picture, above the highest clouds. And, sure enough, the histogram is bimodal. Same if saving in 16-bit tiff.</p><div></div>

[bernard_lazareff]

<p>Then I scanned the same frame on my Nikon LS-2000. And now the sky gradient is nice and smooth (not shown), and the histogram is consistent with a smooth gradient. See graph below.</p><div></div>

[bernard_lazareff]

<p>More detailed information. Both scans made with vuescan. Media: b/w negative. In color tab: generic color negative (other users here find this the best choice for b/w). White point @0.5%, black point @2%.<br /> V700 scan made at 1600dpi. (shouts of "grain aliasing" from the back of the room). But the LS-2000 scan was made at 1350dpi. <br /> V700 35mm holder has been carefully adjusted for height, including index-card shims. The LS-2000, of course, has auto-focus. <br /> Insights, anyone?<br>

Irrelevant (?) information: FP4, D76(1+1) 11min, Minolta Hi-Matic 7sII, orange filter, 1/125 f:5.6+1/2</p>