Good point. Another proper name for Lippmann Process is Interference Process.
>
>I know somebody who lives in Brisbane who makes Lippmann plates for
>astronomers. They're highly valued for this application because of the
>accuracy of their colour rendition.
If it were not for the fact that the source of this post is undoubtedly
reliable I would find the above statement unbelievable. The original glass
plates that could be used for this process were one million times slower
then conventional plates. Emulsions, including fine grain ones, are much
faster today but I still wonder what this process has that cannot be
matched by todays's contemporary color materials.
>Some observatories maintain a collection
>of Lippmann plates exposed at set intervals from earlier this century for
>comparative purposes. Of course there are no problems with fading, unlike
>any processes involving dyes!
Silver processes are not that stable unless a protective toning is used.
I'd go so far as to say that the more stable color slide films, kept in the
dark, will outlast many silver films.
>He does a batch once or twice a year, depending on the number of orders that
>come in.
>
>I haven't actually seen any of the results, but they're supposed to be quite
>hard to see and have to be viewed with a bulb either side inside something
>like a camera bellows to cut down reflections. The plates used to be backed
>by a mercury reservoir that filled a tank behind the plate; a mirroring
>process is used nowadays instead.
I have seen a number of original Lippmann plates at the Bibliotheque
Nationale in Paris. They are tricky to see and are nearly impossible to
reproduce.
>The special fine grain emulsion used for the plates (which are on special
>optical glass with both surfaces perfectly flat and parallel to one another)
>is quite slow, and could only be used for still lifes.
>So, to answer your question, the process is feasible, and is still in use on
>a very limited scale.
Thanks for the info Phil. If you find out more, please tell us about it.
Luis Nadeau
nadeaul@nbnet.nb.ca
Fredericton, New Brunswick, Canada
http://www.mi.net/dialin/awef6t/