Long Exposure calculating?

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Colin Franks
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Long Exposure calculating?
3 months ago

Scenerio: After sunset, getting somewhat dark-ish.

Goal: Long exposure of landscape/sky/clouds with 10-stop ND filter.

If normal exposure time (without filter) is say 1.6 seconds (F11; low ISO), this means about 24 minutes exposure with filter. But how does one account & calculate for the fact that in that 24 minute exposure, it's going to get even darker outside, meaning more time required?

 Colin Franks's gear list:Colin Franks's gear list
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