Re: Filter/Speed/Meter

[Clive Warren <Clive.Warren@xxxxxxxxxxxxxx>]

At 10:03 am -0500 2/10/00, R. C. Lacovara wrote:
>
>Folks,
>
>I see that you share exposure information by stating the filter 
>which you use (often an 89B) and then the film speed. That seems 
>reasonable. But sometimes it's not clear what you are using for a 
>meter. I suppose that light meters are similar in the visible, but 
>do they not differ somewhat in the IR?
>
>In any event, could someone tell me, for either HIE or Maco, a 
>filter/speed/lightmeter combination?
>
>I have tried a Hoya R72 over my Weston III and IV, but despite 
>several sources' claims that these meters are IR sensitive, this is 
>hard to see. I'm trying to rig a better filter mount for one of my 
>Westons.
>
>Thanks,
>
>Bob
>R. C. Lacovara, Ph. D.
>Electrical Engineer in Computer Science Drag and
>Principal Member of Technical Staff

Bob,

The easy way to think about this is that the Maco film is about a 
stop slower than HIE.  So, if you are using an 87 or an 89B filter 
then you should be rating the film at about 12ASA.

Meter cells do indeed differ in their sensitivity to infrared light. 
Luckily there is usually a fairly constant relationship between the 
amount of visible light available and the amount of infrared light 
when you are outside.

Have a wander over to the Infared FAQ (URL in sig. file) and think 
about leaving your meter at home :-)

-- 
All the best,

              Clive   http://www.cocam.co.uk
                      Photographic Services, Filters and Equipment, Infrared FAQ
*
****
*******
******************************************************
*  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  *
******************************************************