RE: ISO for meter w/infrared

["George L Smyth" <GLSmyth@xxxxxxx>]

> -----Original Message-----
> From: owner-infrared@xxxxx [mailto:owner-infrared@xxxxx]On Behalf Of
> Charles Jay Pilzer
> Sent: Wednesday, December 29, 1999 3:39 PM
> To: infrared@xxxxx
> Subject: ISO for meter w/infrared
>
> I am using a Hasselblad with has no built in meter.  I have a Sekonic
L-508
> meter.  I would like to know what ISO to use on the meter for HIE when I
> have one of the following filters on the camera and no filter on the
meter.
>
> 1. no filter
> 2. red 25
> 3. B&W 090 (89B)
> 4. 87
> 5. 87B
> 6. B&W 093 (87C)

I use Kodak Infrared both within 35mm cameras and large format, the former
with the meter within the camera, the latter is a Minolta Spotmeter.  When
using a #25 filter, I meter through the filter, so my Exposure Index is the
same as those few times I shoot without the filter.  When shooting HSI (the
4X5 variety), I simply place the filter over the meter and make my readings
that way.  For this, I normally meter at EI 250 (examples on my Web page).

I only have two opaque filters (R72 and 87C), so I can't give you specific
guidelines for all of the filters you have listed.  However, when I use one
of mine, I use that same #25 filter and meter through it, then add a filter
factor for the filter I will be shooting through.  This simplifies things
greatly.

More important, however, is for you to run a series of tests yourself to
determine how best to use these materials.  I generally point people to my
Web site when suggesting a particular exposure time for HIE/HSI because I
can show the results that I obtain.  It is entirely possible that you may be
looking for something quite different, thus you will want to alter your test
to give you the results you desire.

Cheers -

george

---
Handmade Photographic Images
http://www2.ari.net/glsmyth/

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