Colour Film v BNW Film

Barney

Barney

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Wayne
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How come that the colour films do not seem to blow out the skies as much as the BNW films do?
 
Colour films have 3 emulsion layers with filters between each one. Black and white films (and each layer in a colour film) are only natively sensitive to blue and UV, depending on additives to extend sensitivity into the green and red.

I'll be inaccurate now for simplicity, and not worry about complementary colours in negative films. The blue layer will produce blue dyes in the print if it receives any exposure.

Does a blown out highlight in a digital image register anything in the blue channel in the sky? Rhetorical question.
 
Adding another note to the above - the different layers are usually of differing sensitivities to balance things out.
 
Right, so the blue layer(sky) effectively operates at a different ISO than the red or yellow layer?
 
Barney said:
How come that the colour films do not seem to blow out the skies as much as the BNW films do?
Click to expand...

I think it's just a case of black and white simplifying things. Colour can be a bit of a smorgasbord, and that can be distracting.
 
I can't guarantee that if you make a search using these words

Spectral sensitivity curves colour negative film

you'll see the same as me, but you might, and if so, look at the pictures and diagrams it throws up. I know I get different results on my tablet, win 10 desktop, win 7 running in VirtualBox and Sue's computer. That's the great thing about search engines personalising things - it removes consistency and predictability from searches.
 
And if you should want this sort of data for digital cameras, good luck. I could only find generic information in a text book when I looked for it some years ago. I plotted my own curves for an Olympus E3 and then gave up.
 
A nice evening there spent looking at graphs, on a side note I think I am starting to understand how colour filters work and adjust the sensitivity curves on BNW film.
 
If you want to go down this particular rabbit hole, the best advice I can give you is to read my book. I say that not because I'm self promoting, but because almost everything I could attempt to explain here is covered. Bluntly, it's my final word in the sense that it condenses all I know (or think I know). It will suggest further reading.

If you don't want to take that route, be aware that you can still buy ortho films, and films with extra sensitivity into the red end of the spectrum but stopping short of true IR.
 
will do Stephen,

Get the book into print so I can have a hard copy.
 
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