I would like to know details/facts concerning the spectral sensitivity of
Talbot's Calotype emulsion compared to the sensitivity of Vandyke emulsion; and
of the sensitivity of the Calotype compared to ortho film (or any other film
anyone may know about).
For example, does an image (camera) made with ortho film, respond to the light
spectrum in the same way (or not) as the calotype (also exposed in the camera).
(Although I guess modern coated lenses play havoc with that too!) Or, would a
vandyke emulsion (if it were to be exposed in a pinole camera for example)
respond the same as Talbot's calotype emulsion or the same as his first
photogenic drawing emulsion (also sometimes known as a salt print) exposed
similarly?
Now as far as I am aware, the calotype is only sensitive to the UV and blue end
of the spectrum. Is it exactly the same for the Vandyke or does the addition of
Fe Am Ci, extend sensitivity across the spectrum?
Now I realize this may be a really silly question, but my chemistry knowledge
and knowledge of physics is not what I would like it to be. My interest is
partly to ascertain whether any contemporary emulsion, or combinations, can
actually replicate Talbot's emulsions (of the 1830s and 1840s) with respect to
their response to the light spectrum. I know I could coat paper with photogenic
drawing emusion and expose it in the camera etc etc, but I don't know how to go
about determining relative colour sensitivies. Facts concerning the specific
behaviours of emusions across the spectrum are what I need. If possible.
Somebody???
Many thanks all - in anticipation of many many responses.
Catherine