When the exposure is that long, it's subject to the reciprocity failure
of the film. That could be anywhere from one to two stops, depeniding on
the emulsion. Try 128 and 256 second exposures at f22.
Paul
Ayash Kanto Mukherjee wrote:
>
> Hi!
>
> I was trying to photograph the dial of my table clock illuminated by a
> small tungsten bulb inside. I used program mode in my MZ-M and it
> suggested an aperture of f/4.5 at 2 sec with the flash recommended warning
> blinking. Well, I wanted to take the shot in complete darkness and
> therefore the use of flash never comes in picture. I took the shot and the
> result came out to be overexposed but it was more or less acceptable.
> The lens used was Pentax SMC A 35 - 80 mm f/4-5.6.
> My next experiment was to decrease the aperture by 5 stops, i.e., f/22 and
> therefore the exposure has to be increased by 5 stops, i.e., 64 sec. I got
> a very horrible result. It was severely underexposed.
> HOW THIS COULD HAPPEN? I couldn't find any explaination for it.
> Is the lightmeter working o.k.? I doubt!
>
> Any explaination/suggestion/comment is welcomed.
>
> By the way, I have both the photographs with me. So, if anybody interested
> to see the results, I can scan and send it but this kind of activity is
> dicouraged and therefore I won't do that unless and until anybody really
> interested to see.
>
> Thank you.
>
> Looking for a reply.
>
> - Ayash Kanto.
>
> -
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