bio and EIR -- how does it work?

[Alastair Rucklidge <A.M.Rucklidge@xxxxxxxxxxxxxxx>]

Please fill in this bio:
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- - Name: Alastair Rucklidge

- - Profession/Study: Mathematician

- - Country: England

- - Personal history of photography: I started learning B&W when I was an 
undergraduate, but let it drop for many years, until a couple of years 
ago when I managed to get a convenient darkroom set up. I've been 
shooting Kodak HIE since then, as well as regular B&W and slides, and 
slowly getting better at printing.

- - preferred subjects: Landscapes (HIE) and natural details (colour)

- - materials (film, filters, paper, chemistry): 
 film: Kodak HIE (of course), Tmax, Velvia, Kodachrome 200, Velvia.
       I'm experimenting with Ektachrome IR. 
 filters: mainly a 25A for HIE, but I've tried an 87C -- the thin polyester 
          keeps blowing out of my filter holder!
 paper: Ilford MG IV in RC and FB. Want to try some of the Kentmere papers.
 chemistry: ID-11 (which I pretend is the same as D-76) for HIE, and 
            standard Ilford developer for paper. Also use thiocarbamide toner.

- - format (35mm/medium format/large format): 35mm and 6x6

- - Other strange hobbies: Does being a mathematician count?

- - How did you find out about this list: I've been lurking pretty well 
 since it started, so I can't remember how I found out!

- - Expand on anything photographic you like:

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This is a great list, and I've learned a lot from it. Now I have a question:

How does EIR work? I know there are three layers, sensitive to infrared; are
the other layers sensitive to red and green? What colour dyes are produced by
each layer, and how do these mix? I'm trying to work out (a) why the sky comes
out blue on EIR when shot through a yellow filter, if none of the layers are
sensitive to blue; (b) how to get green in the image (I've got red, magenta,
blue, cyan and yellow, but no green so far).

I'm trying to put together a table like this to help previsualise the results:

- --------------------------------------------------------------------------

perceived colour   light from subject   colour on EIR through a yellow filter
and typical subject                   

- --------------------------------------------------------------------------

black              none                 black
                                        
black              IR                   ???
                                        
red                red                  seems to come out yellow
                                        
red                IR + red             
                                        
green              green                
                                        
green              IR + green           red and magenta
sunlit foliage                          
                                        
yellow             red + green          
                                        
yellow             IR + red + green     

blue               blue
sky

and so on...

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Any assistance would be gratefully received!

Many thanks,

Alastair Rucklidge

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