Fantastic app that allows me to focus on setting up my camera/filter, composition, etc -- instead of calculating exposure times manually. Contrary to the previous review I find the app to be very accurate regardless of what brand ND filter I use (Hoya or Lee) as it works off of stops not the particular brand type. Furthermore, you can easily adjust exposure in 1/2 stop increments by swiping the timer if you feel it is necessary either to compensate for your metering technique or for reciprocity failure when using film.
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