Re: IR metering simplified or "what the.... "

["Jon Witsell" <wfc27@xxxxxxxxxxx>]

Hmmm,

I have only shot about 5-6 rolls of IR film (Kodak HIE) to date and have 
been happy with the results: 2-3 great pictures per roll, 20 okay, and the 
rest...well. I have been using a Red 25 filter, but I just purchased an 
87c--and am trying to figure out this whole film speed/rubber chicken/filter 
factor thing so I can give this 87c a solid try.

Usually, with the Red 25, I just set the film speed to 200, meter through 
the filter, bracket +/- one stop and everything seems to work. The last roll 
I shot I used both filters and wasn’t as impressed with the results 
(However, this was the first roll of HIE that I processed myself, maybe that 
had something to do with it--but I don’t think so). I couldn’t see a 
consistent pattern of what happened other that the shots w/the 87c weren’t 
as sharp.

Also: since I was shooting at 200, in order to get enough light I had to 
crank open the aperture all the way (which is why I think some of the last 
roll didn’t look as sharp). I am unfamiliar with bracketing with the film 
speed. I just always set my camera at one film speed and bracket with 
f-stops. I remember thinking that I was going to have to get more film speed 
in order to close down the aperture to get the depth of field I wanted. I’m 
still a bit new at this...

Okay, so I tried the calibration method below and this is what happened: I 
took my Canon AE-1P outside on a sunny day here in Seattle (one of four we 
have had this year...) and set it to f/11 & 1/125 and put on a Red 25. 
Pointing it at your average hedge, the meter indicated f/11 at a film speed 
of about 530 (the first detent above 400).

I changed it to f/2.8 and 1/125 and put on the 87c. Pointing again at your 
average hedge, the meter indicated f/2.8 at a film speed of about... the 
same--530. So what now? I thought the film speed would increase with the 
87c.

I guessed that when I took the 87c off and metered the hedge I would get a 
reading for a five-stop-smaller aperture--which is exactly what happened.

I think this next roll of HIE I will shoot at 530 (can I shoot it higher? I 
want to be able to use a smaller aperture) and just use the 87c.

Any suggestions?

Jon, (my bio will follow shortly--and I promise, it won’t be this long!)

>Sorry, but I have to play the devil's advocate on this topic.  A very quick
>and easy way to calibrate your camera's inboard light meter to IR light is
>outlined below:
>
>1. Take your camera outside around noon on a bright sunny day and adjust
>your aperature and shutter speed to f/11 & 1/125.
>
>2.With a 25 Red filter over your lens adjust the film speed of your camera
>until the onboard light meter shows you that f/11 and 1/125 is the correct
>exposure. Use this film speed to shoot IR film.
>
>3. Your camera meter is now calibrated to read IR light fairly accurtely.
>
>This has worked well for me using both the Nikon F90x/N90s camera and the
>Pentax 67II camera.  I suppose your milage will vary depending on the
>senstivity of your inboard camera's metering system.  But it seems to me
>that SO MANY BEGINNERS get frustrated with the metering issue to the point
>that they give up.  This method is simple and should get beginners
>interested before they give up.  Some other notes:
>If you're using an 29 filter use f/8 and 1/125 as a calibration point.
>If you're using an 89B filter use f/5.6 and 1/125 as a calibration point.
>If you're using an 87 filter use f/4 and 1/125 as a calibration point.
>If you're using an 87C filter use f/2.8 and 1/125 as a calibration point.
>As you use darker filters your film speed will increase.  If I remember
>correctly, I think I use EI=5000 TTL with an 87 filter.
>
>Good luck Rolland

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