Continuing 'I'm done with Velvia'

Poisson Du Jour said:

Roger,
The lab that handles my RA4 production uses a wet chemical machine with LED exposure. It is not a new development, nor even recent, but a process that has been around for 20-25 years at least. I do not know why you are mentioning "laser"; such things are not used unless by some full-digital means they are employed in pure digital printing (which is what I am definitely NOT involved in).

Click to expand...

An LED exposing unit cannot be much older than 20 years because the blue LED was invented 1992 and it took some years to make it commercially available.
It does not matter how the light for exposing RA-paper is created. LED or Laser - all of them use 3 different wavelenghts RGB.
Your image is scanned and transferred by any electrical way to any kind of exposure unit. I don't see a big difference to "digital".

I think many people think about a laser printer when they hear "laser exposing". This is NOT the same! A laser printer uses a fine raster of dots to create pictures similar to pictures in a printed magazine. Each color or the black of b/w can only be full "on" or "off". Mixture of color is done by addig more or less dots of each color side by side or overlapped into a raster.
This is the same with inkjet printers, while their raster is very fine. But you never can print a single dot with 50% magenta, 20% yellow and 10% cyan! So this kind of printers are "pure digital" because each color can only be "1" or "0".

A laser imager like a Lambda (or even my homebrew DIY-imager exposes all 3 colors to the same dot and controls intensity of each color in that dot. So each single exposed dot contains all possible combinations of R+G+B.
While the PIXEL RESOLUTION depends on the image file and the resolution of the exposing unit, the COLOR RESOLUTION is way beyond commercial laser- or inkjet printers.
With traditional printers, color resolution is a result of physical pixel resolution.
If you think about a theoretical low resolution of 10 DPI and print a light brown color, your desktop printer will create a field of clearly visible dots C, M, Y and black with lots of white between. You have to view it from distance to see the "real" color.
A laser imager for RA-4 will create a field with all dots of light brown. So color resolution does not depend on dot raster resolution.

This is off topic, but you should know it when comparing different technologies and comparing between analog and digital.

Joachim

hi OP
i am nearly done with velvia too,
i only have 50 sheets left !
i develop it in coffee and dektol ,, it loves it !
YMMV

To further muddy the waters Poisson Du Jour, a Laser and LED are not digital devices. They have a varying intensity with how they are electrically driven. They may be implemented analog or digital. That would be up to the engineers of the equipment and may have nothing to do with your assumption.