"Pepper grain" (was Minolta Multi Pro)

[Roger Smith <rsmith@xxxxxx>]

At 4:58 PM -0800 4/3/02, Arthur Entlich wrote:
>This issue of "pepper grain" brings up a number of issues.  Roger 
>Smith and I were looking at several phenomena in regard to different 
>films which didn't appear to be dirt or dust, or grain, but did show 
>up on the scan when highly magnified.
>
>Roger found one defect which I don't think has been fully addressed 
>yet, very small bubbles in the film base, which he was able to 
>directly correlate (by use of a microscope) these bubble positions 
>with artifacts on the scanned image.  Further, he determined that 
>these bubbles showed up not only in scans, but when printing the 
>image via standard darkroom techniques.
>
>There was a second phenomenon which was this secondary grain which 
>did not correspond with the real grain.  At the time, we were 
>discussing this I suggested there might be some component of the 
>filmbase that the scanner CCD could see that wasn't visible through 
>other methods.

	Art is correct - I looked at a number of films through a 
high-power compound microscope and I could clearly see countless tiny 
bubbles in the outside protective coating over the emulsion. These 
bubbles did seem to correspond to the tiny black specks I was seeing 
in my Minolta Scan Dual II scans, as reported by Reichmann and Rains, 
quoted by Kennedy McEwen.
	Unlike Reichmann and Rains, I saw these bubbles in every film 
I looked at, from a 1976 Kodachrome slide to yesterday's Fuji Velvia 
and Kodak Gold 200. The manufacturer seemed to make little difference.
	I had never seen these effects before (after 25 years of 
Cibachrome printing), and they didn't show up on scans made by my 
Canon FS2710. It's just when I switched to a Minolta Scan Dual II in 
the summer of 2001 that I started noticing this "peppery" effect. In 
fact, that is partly what started Art's and my "quest" for why 
Minolta scanners emphasize film defects.
	As far as the specks showing up on darkroom printed images, I 
did re-examine some 11x14 Cibachromes I printed ten years ago. By 
examining light areas of the prints under a loupe, I could faintly 
see tiny specks that looked very much like the "pepper grain", but 
they were completely invisible under normal viewing conditions.
	Very interesting.

Regards,
Roger Smith

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