Reciprocity question - real basic

[gevalia]

The following is a link to the Velvia 50 RVP data sheet. I am trying to understand its reciprocity correction and am confused. The chart on page 3 (to me) reads that from 1/4000 to 1 sec we have no reciprocity issue. Then at 4 secs, we apply +1/3 stop to correct. Then at 8 secs, we apply +1/2 stop, etc.

What do I do between 1 second and 4 seconds? Between 4 and 8? etc? It says above the chart "However, for exposures of 4 seconds or longer, ..." which leads me to believe that from 1 to 3 seconds, I do not compensate but then why does the chart say 1/4000 to 1 second?

Uhhh.


http://www.silverprint.co.uk/PDF/Velvia50AF3-960E_1.pdf

[BarryS]

If you want to get obsessive, you can use curve fitting software to derive an equation based on the listed timepoints. You can also draw a little graph--or you can guesstimate the times. I've tried every method and guesstimating works as well as anything.

[cyrus]

The following is a link to the Velvia 50 RVP data sheet. I am trying to understand its reciprocity correction and am confused. The chart on page 3 (to me) reads that from 1/4000 to 1 sec we have no reciprocity issue. Then at 4 secs, we apply +1/3 stop to correct. Then at 8 secs, we apply +1/2 stop, etc.

What do I do between 1 second and 4 seconds? Between 4 and 8? etc?

You can indeed interpolate aka guesstimate or use a curve-fitting applications (available online.)

ANyway, I think the chart means that you apply +1/3 stop between 1 TO 4 seconds. The exposure time row should be read as "To" 4 second, "To" 8 seconds etc.

[gevalia]

Nope, not obsessing. I just want to know how to read the chart since it is not clear. Maybe I should have said Velvia 100 where the exposure time is in "minutes" not seconds. I have not done any really long exposures and am starting to now. And there's a big difference between 4 "minutes" and 8 "minutes". Again, I was just looking for how everyone reads these charts.

Thanks Cyrus for the answer.

If you want to get obsessive, you can use curve fitting software to derive an equation based on the listed timepoints. You can also draw a little graph--or you can guesstimate the times. I've tried every method and guesstimating works as well as anything.

[Darren Kruger]

Also note the increased times on the data sheet take into account the filters Fuji recommends to keep the colors accurate.

-Darren

[cyrus]

Thanks Cyrus for the answer.

No prob but I don't think 1/3rd of a stop is something to be concerned with much.