Re: Two questions -- About InfraRed Emulsions and ISO

From: Editor - P.O.V. Image Service (editor@p-o-v-image.com)
Date: Sun Jan 30 2000 - 19:44:36 /etc/localtime

Don Bryant wrote:

>
> Please explain this statement. What is the "wood effect"?

The wood effect is the tendency of green photosynthesizing foliage, when
illuminated, to appear white and diffuse in Black & White IR imagery...

Human skin exhibits the same characteristics to some degree in B&W IR
imagery...

Blue light will swamp the image if it is not filtered out and the effect is no
longer apparent..

It is a result of the IR and Near IR light proceeding through the superficial
layers of the leave/skin and being reflected by the water bearing layers..

Hope that helps....

> And do you really
> mean "without a red filter or *without* an IR
> filter"?
>

Without a red or IR filter..

The effects are visible with a red filter...

A deep red filter offers more pronounced effects...

And a visually opaque IR filter accentuates the effects to the maximum
possible...

Keith 

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