[LRflex] Re: Was a bunch of stuff, black fabric

OK David.  I am ready to tackle the black fabric question. Still about 30 
message behind, though.

I guess I really don't have an answer, or a guess like Colin, but I do have 
a few thoughts.  The IR can only come from two sources.
1)  Light is being absorbed by the dark pigments and degraded to heat and 
re-radiated.  This is happening in both non-synthetic and synthetic 
materials.
2)  Ambient IR is being reflected from the surfaces.  I assume this is also 
happening to some extent from both fabrics.

So, how to figure out what is going on.  I could suggest two possible 
experiments.

1.  Find some synthetic and non-synthetic black material that when 
photographed with film or read with a light meter give the same black 
readings.  They absorb the same amount of visible light.  Now photograph 
them in a very cold room (walk in freezer or outside on a day like today) 
and see what the results are.  Maybe synthetics re-radiate at a different 
wavelength than non-synthetics?

2.  Using an IR flash, photograph them in total darkness to see if there is 
any difference in what they reflect.  Maybe synthetics reflect more IR than 
non-synthetics.

I do not think there is any reason to believe that just because an object is 
black it behaves the same as far as absorbing or reflecting in the IR range. 
  Some materials may be very good at absorbing visible and IR, and others 
only visible.

I don't have an IR flash nor do I have an M8 to try these.  Also


>From: David Young <telyt@xxxxxxxxx>
>Reply-To: leicareflex@xxxxxxxxxxxxx
>To: leicareflex@xxxxxxxxxxxxx
>Subject: [LRflex] Re: Was a bunch of stuff, now Dark Desert Clothes
>Date: Sun, 26 Nov 2006 09:52:38 -0800
>
>Aram offered:
>
> >Sorry, I am behind in reading.  Maybe someone already said this.
> >I read an article long ago about dark desert clothes.  It seems that the
> >dark clothes absorb the light and get hot, and this heat cause the air
> >inside the clothes, which are loose fitting robes, to get and hot and 
>rise.
> >This draws in cooler air underneath and creates a sort of air 
>conditioning
> >system - convective cooling.  Of course it does not work with a black 
>three
> >piece suit.
>
>
>Hi Aram!
>
>Now that's the best (and the only good) explanation for black robes
>in the desert that I've seen!
>
>Unfortunately, black also radiates the heat better, which is what
>causes the M8's "magenta twist" - especially with synthetic fabrics.
>
>Does your science wizardry extend to explaining why synthetic fabrics
>would cause more problems than, say, cotton or wool?
>
>Cheers!
>
>---
>
>David Young,
>Logan Lake, CANADA
>
>Wildlife Photographs: http://www.telyt.com/
>Personal Web-pages: http://www3.telus.net/~telyt
>
>
>
>
>------
>Unsubscribe or change to/from Digest Mode at:
>     http://www3.telus.net/~telyt/lrflex.htm
>Archives are at:
>     http://www.freelists.org/archives/leicareflex/

_________________________________________________________________
MSN Shopping has everything on your holiday list. Get expert picks by style, 
age, and price. Try it! 
http://shopping.msn.com/content/shp/?ctId=8000,ptnrid=176,ptnrdata=200601&tcode=wlmtagline

------
Unsubscribe or change to/from Digest Mode at:
    http://www3.telus.net/~telyt/lrflex.htm
Archives are at:
    http://www.freelists.org/archives/leicareflex/

Other related posts: