Re: rodinal developer for infrared

[John Sparks <sparks@xxxxxxxxxx>]

>Kayo Matsushita wrote:
>> 
>> George, you mean you set the ASA setting on your meter to 8 when metering
>> through the filter? Reading your messages on various occasions (like on
>> Usenet, FAQ, and this mailing list), somehow I was always under the
>> impression that you meant your effective EI of the film was 8, which
>> translates to ASA setting of either 32 or 64 (depending on the filter
>> factor you use) when using through-the-filter metering...
>> 
>
>To my mind they're the same.  One can either meter with a value of EI32
>then open up two stops for the #25 filter, or meter through the filter
>with a value of EI8.  This whole matter unfortunately gets a bit
>confusing when the method of metering is not mentioned.  I always meter
>through the filter, as this method has always worked well for me.

I think this is backwards.  If you meter at EI32 in broad daylight, you
get something like f/16 at 1/30 sec.  Open up 2 stops and get f/16 at
1/8 sec.  This is the same as metering at EI 8 without a filter.  Put a
#25 filter on at EI 32 and meter through it, you will get something like
f/16 at 1/4 sec (assuming a typical meter reading is reduced by 3 stops
with this filter).  Since filter factors are typically less for IR than
regular films with red filters and you may only want a 2 stop correction
so you need to actually increase your speed by a stop to EI 64 to get
the same reading through the filter as you would get without the filter
and applying the correction.  Metering through the filter at EI 8 is
about the same as metering without the filter at EI 1!

Seems like several people here have said that you need to give extra
exposure to the Konica film to get a good IR effect.  I can understand
that you may like the way the very overexposed negatives print, but
metering at EI 8 through the filter (TTF) is not the same as metering
without the filter at EI 32 and applying a 2 stop correction.

John Sparks

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End of INFRARED-PHOTOGRAPHY Digest 62
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