At 07:51 AM 10/28/1999 -0400, Paul wrote:
>In a message dated 10/27/99 8:41:28 PM Eastern Daylight Time,
>wright@xxxxxxxxxxxx writes:
>
>> OK folks, I have a special pinhole for my OM-2n.
[snip]
>>stayed open for about a minute, then closed. Was this an acurate exposure?
>Theoretically you should get a good exposure. An OM-2n, when metering
>in auto mode, doesn't care what the actual aperture is. It just
>measures the light reaching the film and integrates it over time. An
>exposure that long probably will require adjustment for reciprocity
>failure.
[snip]
Reciprocity is the main thing to watch. Here are some numbers from John
Shaw's book "Outdoor Photography."
Film 1 Sec 4 Sec 8 Sec 16 Sec 1 Min
Kodchrome 25 +0.5 +1 +1.5 +2 +3.5
Kodchrome 64 +1 +1.5 +2 +2.5 +3.67
Fuji Velvia -0- -0- +0.5 +0.67 +1.33
Fujichrome 100 -0- -0- +0.33 +0.67 +2.67
You can see from these films that a 1 minute exposure requires a bit of
compensation.
Wayne
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