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Greg Gibbons
9-Nov-2009, 14:13
The spec sheet for Velvia says reciprocity problems begin at 4 seconds, and at 16 seconds recommends +2/3 stop and a 10M filter. (As I recall.)

But I don't really know what that really means. Do I simply expose it for an extra 10 seconds to accomplish the +2/3 stop?

Next, if I get a color shift that can be corrected with a 10M filter, can that be corrected identically in photoshop? Or is there loss on the film from the color shift that can't be fixed digitally?

Thanks in advance.
Greg "I don't have a great catchphrase yet" Gibbons

Joanna Carter
9-Nov-2009, 15:24
The spec sheet for Velvia says reciprocity problems begin at 4 seconds, and at 16 seconds recommends +2/3 stop and a 10M filter. (As I recall.)

But I don't really know what that really means. Do I simply expose it for an extra 10 seconds to accomplish the +2/3 stop?
That is, indeed, what it means.


Next, if I get a color shift that can be corrected with a 10M filter, can that be corrected identically in photoshop? Or is there loss on the film from the color shift that can't be fixed digitally?
Correcting with Photoshop can never be the same as using a filter on the lens. Without a filter, the film will be exposed, lacking in magenta and with excess green. Although you could cut back the excess green, how would you decide which parts of the picture were too green or not magenta enough?

Having said all that, 10M is not the most serious of casts and should be correctable if you really don't want to go to the trouble of getting a filter.