What about the schwarzschild effect? http://en.wikipedia.org/wiki/Schwarzschild_effect The ISO of film drops with longer exposure times. No idea if it also applies to digital sensors.
On 19 February 2010 00:42, Peter Zalabai <[email protected]> wrote: > Hi list, > > I had a question that none of my friends could answer exactly (we all had > our guesses :D). > What happens if you stack for example 2 ND8 filters? Will it be ND16 or ND64 > equivalent? > > So I decided to order 2 more ND8 filters from EBay and done a test. But > during the tests I found out that ND filters are not that Neutral Density as > they should be... > More at my photoblog: http://15kb.blogspot.com/2010/02/nd-anomaly.html > > Regards, > .timber > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
