Re: polarizer?

[George L Smyth <glsmyth@xxxxxxxxx>]

--- paul schuster <paul@xxxxxxxxxxxxxxxxx> wrote:
> hello list!
> 
> I recently received the maco IR 4x5.
> I have only exposed a couple of sheets.
> 
> my question is:  are there any special considerations when using a polarizer
> and IR.  I stacked the filters (#25 red and the ploarizer).  I had heard it
> would only act as a neutral density filter when using IR (what I was going
> for).  I had the red on first and then the polarizer.  now normally, I would
> turn the ploarizer until I got the desired effect.  but I was unable to see
> much change through the red.  I guess next time I will put the polarizer on
> first and red last.
> the day was a bit hazy.

The order in which they are put on makes no difference.  The polarizer will
work with your visible light but not infrared radiation.  Depending upon the
scene, the polarizer may or may not show a noticeable affect.  The hazier the
day, the less the affect.

> also!:  is my math correct in my filter factor of 5.5?  a filter factor of 3
> for the 25 red, and 2.5 for the polarizer.  bringing my maco ISO 100 to
> around 3 or less ?

Assuming you are using a circular polarizer, the filter factor will be
determined by how the the polarizer is set.  Remember, you will only be
affecting the visible component of what will be striking your film.

Cheers -

george

=====
Handmade Photographic Images
http://members.home.net/hmpi/

__________________________________________________
Do You Yahoo!?
Get Yahoo! Mail - Free email you can access from anywhere!
http://mail.yahoo.com/
*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************