Re: Konica 120 infrared

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On  6 Sep 96 at 19:51, JoePaduano@xxxxxxx wrote:

>  Strong sunlight is best to achieve strong contrast & the infrared 'look' of
> white vegetation.
>  Infrared reflection is strongest at midday and in the summer. 

Mmm....what do you mean with midday? As opposed to noon? Same goes
for the early morning at least. The longer shadows in either case
will also add to the contrast. The way I see it, it is not so much
more absolute IR reflection, but relatively. This is easy explained
with the variation of UV over the day: maximum UV is present at noon,
so the relative amount of IR *must* be less at that time. That is not
said that the absolute amount is less, but with a #25 you use both
visible and IR, so the difference probably affects the final
exposure. And most of us meter visible light, so the variation of IR
within the spectrum could add to exposure error as well.

FWIW, in this Agfa-Gevaert IR book they state that sunlight of 
6000Kelvin can be split in 40% visible, 59% heat/IR, and 1% UV.

Btw, it also seems as if spring foliage reflects more IR than summer
and fall foliage. Any bio experts present who could explain the
theory behind this?

 
--
Bye,

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The difference 
between men and boys
is the price of their toys

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]

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Topic No. 8