Re: EIR EI.

[Tom Campbell <tcphoto@xxxxxxxxxxxxx>]

Alan, what filter(s) were you using?  And was it E6 or AR-5 process? 
And, are you metering through the filter?  Just some thoughts that might
nail down the problem.

I'm finding that for most filters, 200-250 is about right.  With a green
(X1) it's at least a stop slower.


 
      After running 3 rolls of EIR through in the last month or so, I
have
>      come to the conclusion that I have no idea of the best EI. I tried one
>      roll on EI250 and the other two on a mix of 250,320 and 400. It seems
>      that even 1/3 to 1/2 of a stop in overexposure causes a complete loss
>      of colour saturation, especially in the sky.

> 
>      The only thing that I can think of is that maybe (slight lack of
>      general knowledge on atmospheric spectral data here), in my part of
>      the world, the background IR is greater than in Rochester.

After spending a year there, I can't imagine a place with *less* IR than
Rochester (joke--actually did some nice B&W there).

 Can the
>      ambient light be low, but ambient IR be high ?

Most definitely.  To verify, try shooting IR at night.  But in most
cases, the IR/visible difference isn't that great in normal lighting
situations.  Obviously, more of a problem with chromes than HSI.
> 
>      I usually end up getting about 1/2 the roll being decent shots with
>      good saturated colours, the others are just magenta/pink and white.
> 
>      Any idea ?
> 
>      Alan.
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