RE: filmscanners: Magnification of light - AND brief density math lesson...

["Austin Franklin" <darkroom@ix.netcom.com>]

> [rafe b:]
> >> I'm afraid I don't understand.  Doesn't the proper exposure
> >> depend on the image under consideration?
>
>
> [Austin]
> >No.  More so the film.  The image data only spans a small part
> of the 16 bit
> >range.  Increasing exposure time only increases DMax.
>
>
> Well, this again is contrary to my experience, but I
> don't scan BW film all that much.  I would have thought
> that BW film would exercise the scanner's dynamic range
> more so than color negative film.

They are about the same, 2.4 to 2.8.

> On the film scanners I've used, when exposure needs to
> be messed with at all, it's always a result of an
> over- or underexposed image.

Not with the Leaf.  They even go out of their way to say to scan at minimum
exposure of 16ms for everything but chromes, and they say it gives a DRange
of 3.3, and the only advantage of longer exposure is getting higher DRange
of 3.7.  Of course, exposure time compensation may help for some
circumstances.

> Either that, or an image with a lot of contrast, where
> I'm making two separate scans which I will merge in
> Photoshop.  There seems to be less need for that trick
> as I move to better scanners, tho.
>
>
> rafe b.
>
>