Re: InfraRed and Water - A comprehensive approach - Final Chapter

["Rolland Elliott" <rolland_elliott@xxxxxxxxxxx>]

A few more points to clarify........

Kieth wrote: "I will assume over 20 scientific studies, done over nearly 70 
years by
varying scientists,  showing optical absorptive qualities of water
throughout the spectrum will satisfy you... Look at the data and weep
(those near IR-absorptive tears)..."

You are absolutely right Kieth! I'll just have to burn my "American Infrared 
Survey Book"
because it has an IR picture of a lady getting out of a lake and the shallow 
shoreline water looks transparent. According to you, it should be black or 
at least very dark.  I'll also have to burn my book " Photography by 
Infrared, It's principles and applications" because it blatantly states 
that:

" When infrared film is exposed through a red filter, the sensitization in 
the red and near infrared makes the film useful for penetrating water to an 
appreciable degree."  It also has a graph on page 168 that shows a greater 
than 90% transmission of IR light below 900nm (which is similar to what 
Kodak HIE film can record) through 1 cm of water. I'll also dig through all 
my old negatives and pictures and purge any of them that show water that 
looks even slightly transparent.

>From now on all my IR water shots will be dark and black! Who am I to stand 
in the way of your precious data tables? All sarcasm aside, what does the 
unit of 1/cm for absorption mean on that web site?

Kieth further states, "Yes and you can see through small "window panes" of 
ice... BUT YOU CAN'T
see through even 5 feet of the same ice!"

This is true for most substances many people consider transparent.  Thin 
pieces of scotch tape are transparent, but a five feet thickness of scotch 
tape, certainly wouldnt' be. A thin 87 IR gel is transparent to near IR 
light but a five foot thickness of the same material would not be, besides 
at $25 bucks per gel that would get expensive. I guess it's just your point 
of view. I've been talking mainly about small amounts of water, while you've 
been talking about large ones.  The thicker the water the more IR it 
absorbs. Therefore small amounts of water absorb relatively small amounts of 
IR while larger amounts of water absorb rather large amounts of IR.

"Just because absorption is not easily measurable with
small volumes of water, that does not mean it is not a fact!"

Everthing absorbs light to some extent (unless you are using a vacuum), so I 
guess you're right on a theoretical level, but what is to be learned on a 
practical level from this info?

<<Your ancestors must have been the ones at the dock telling Columbus that 
the world could not be round.. Why? "See, to all appearances it is flat!">>

You're right again! How did you know I was related to Columbus?

"Or, wow, how cool it would be to have a cheetah the size of an elephant.."

You're right again! That would be really cool! Or how about a space ship 
that travels faster than light and has IR and UV sensors all over it. That 
would be extra cool!

"The steelworkers open the blast furnace door,
allowing huge amounts of heat (mostly as IR radiation) to pour out at us 
both...Guess who gets the permanent second skin of rubber (or Dupont 
neoprene) and watches his flippers curl up? "

This is a great false analogy; very funny too, even if I am the one turning 
out a little overdone. You are talking about how you would be protected by 
your wall of water because water absorbs far infrared energy and heat, but 
this whole discussion is not about far infrared energy and heat, it is about 
water and near IR light that can be photographed.  Last time I checked IR 
film doesn't record heat, so your analogy is a rather poor comparison.

I wrote:
>>you're .....talking about theoretical IR photographic situations, that 
>>you've never had
>any hands on experience with.
Kieth's response: "I make my living taking photos...INCLUDING INFRA-RED 
IMAGES."

Good for you! Wouldn't it be great if more of us could do this? Let's see 
some of those Underwater IR pictures you claim to have experience with. 
Afterall I've shared specific book and picture references for my agruments, 
I even did a couple of quick tests with an IR camcorder, the least you could 
do is share.

"In fact, if you want, I will approach my contacts at Kodak, RIT, and 
elsewhere and get you an actual spectral analysis of the spectral response 
curve for H20..."

No, need to do that I already have one. It's on page 168 of above referenced 
book. But you might want to get one for yourself. Better yet, come over to 
my office and I'll take an IR picture of you crying I'm sure the tears will 
show up to be quite transparent in the final picture.  It may be seen from 
the chart that in a thickness of 1cm, water is transparent to light of 
wavelengths in the visible spectral region (400-760nm); from 700 to 900nm it 
is about 90% transparent; it is only partly transparent in the longer near 
IR region; it is opaque to radiations longer in wavelength than 1400nm  in 
the infrared.

Mine's for 1 cm thick water, if you have one for 1 or 2 meters of water they 
would be neat to compare. One thing you could do is get rid of that legal 
mumbo jumbo disclaimer for me;  I find them particularly annoying.  Peace 
Rolland

And lastly Karl wrote:
"I did my own tests Rolland, did you do yours under purely IR light, or 
under
normal light with an IR filter over the front?"

My response:  Mine were done with an 88A filter which is very close to an 87 
filter.

>"Mine were done:
>a) under IR with a video camera, then
>b) photographing into a pool of water 1 inch deep with HSIR and an 87 
>filter
>over the front (result: black water)"

That's interesting that your experiment conflicts with mine and also 
published data on IR transmission through water.  Did you use a regular 
camcorder or an IR camcorder?

Peace Rolland
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