Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Digital Photography > How far can this lens "see-through"?

Reply
Thread Tools

How far can this lens "see-through"?

 
 
Dave Martindale
Guest
Posts: n/a
 
      11-28-2006
"J. Clarke" <(E-Mail Removed)> writes:

>The fabric isn't all that special. Ever have a 16 year old ask you not to
>use nightshot mode on a Sony camcorder because her Daddy shot her 15th
>birthday that way and "it was embarrassing"?


What matters is the IR absorption properties of the dyes used on the
fabric. "Black" fabric may absorb only visible light while passing IR
freely (apparently typical of organic dyes), or it might absorb all
frequencies of light.

The dyes used in colour film pass IR pretty freely; that's why it's not
safe to look at the sun using any number of thicknesses of colour film
stacked together. (Not much visible light gets through, so your eyes
don't blink or squint, but most of the IR is still getting through and
will cause damage). That's also how film scanners with "ICE" work -
they make a 4th pass using IR light, and the image dyes are transparent
in IR but dirt and scratches appear dark.

On the other hand, the metallic silver in B&W negatives does absorb IR,
and so does carbon black in ink, so these are opaque even in IR.

Dave
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Re: How include a large array? Edward A. Falk C Programming 1 04-04-2013 08:07 PM
ToolTipText pop up far far away from mouse pointer RC Java 2 01-08-2008 12:54 AM
Taking table-less CSS design far too far Andy Dingley HTML 45 06-11-2006 07:14 PM
How far can you get the drunk? rupert NZ Computing 10 01-25-2005 07:18 PM
OT: Problem no one can solve so far peace to all A+ Certification 11 07-05-2003 03:00 PM



Advertisments