Digital BW, The Print

Olaf,

the key technology for producing bw negs from digital files has been the LVT. 
That stands for Light Valve Technology and is a company that Kodak bought 
in the early nineties. It is sort of an Iris kind of set up in that a piece of film is 
attached to a drum which spins as a head scans across the width. The smaller 
of these can print 8x10 film, but bigger units can go to 11x16 (if my memory 
serves). They go up to res80 (2032 dpi). Because essentially the head shoots 
a tiny spot of light (modulated by the valve) the resultant film looks seamless. 
No scan lines, no raster pattern. 

However, they are designed with color transparencies in mind. Their limitation 
comes when exposing bw because of the need to reach a certain dmax for 
adequate contrast in darkroom printing. If they have to put out a lot of light, 
they tend to flair. So, a lab that sets them up for bw has to decide how much to 
push (usually TMX, sometimes TechPan) vs what LUTs to write for the pushed 
characteristic curve. As a result, there is no single standard  and you need to 
work with the lab and your printing paper to work around some limitations.

Essentially the density range (DR) of the original camera neg has to be 
compressed to whatever the dmax of the LVT is. In the processs, the tonal 
arrangement of the steps in the middle may shift and your paper characteristic 
curve may not like the new neg. 

Going to a higher sensitivity is not really an option because you end up with 
two sets of grains. Also an issue is that the size of your original neg may be 
changed to fit a 4x5 (printable 3.5x4.5) or larger. That may introduce other 
changes in your darkroom setup (lens etc).

 I  have plotted curves from negs from different labs and different setups to 
track how they interpret the grays in the file. I generally choose the snapier 
negs with the higher dmax. Even so, I will end up jumping two grades up to 
accomodate the shorter DR of the digital neg. That means that if I printed at 2  I 
will end up at close to 4 (in Magenta equivalents on my color head). But 
bottom line, you can get very good results and can exhibit straight and 
semi-digital (new term?) side by side without being obvious.

From what I hear, the same applies to a competing technology, sold by Durst 
as the Lamda and related line of printers. They work by RGB lasers and can 
take bw neg film. But I will let others who know more fill us in on that. Maybe 
someone from A&! can come and explain how the Durst machines work. If 
Benoit or Phil are reading this, perhaps they can help.

There is another line of technology that Martin mentioned, based on a CRT 
tube. These are the so called film recorders which are used in applications 
that are not as critical - such as presentation slides etc. I also don't know how 
far along they have come, but none of the high-end labs, that I know, use 
them. Because they are the most affordable (but not cheap!), they can be very 
useful for duping, stock portfolios etc. I don't have much experience with them 
though.

I hope this helps.


Antonis



--- In DigitalBlackandWhiteThePrint@y..., "Olaf Ringdahl" <o.ringdahl@a...> 
wrote:


>  My particular interest right now is in finding ways to go from film
> negatives, through computer processing, to final, archivally processed
> silver prints. There are several ways to accomplish this and I would like to
> explore the possibilities