PDA

View Full Version : Make a 24h Exposure



ThePenguin
16-Jun-2012, 15:48
If I want to do a 24h exposure with an ISO 100 film, how do I calculate which aparture I should use?

It's about 18h of light, 2h of twilight and 4hours of darkness.

vinny
16-Jun-2012, 15:57
well, the smallest one you got........
an then there's reciprocity.

ThePenguin
16-Jun-2012, 16:06
well its a pinhole-camera and I have ND-filter aswell, but is there any way to calculate roughly?

Jim Andrada
17-Jun-2012, 23:19
Try one and see what you get and go from there?

polyglot
17-Jun-2012, 23:43
The overnight won't register at all compared to the daylight unless you use very different filtration/aperture at night.

18 hours is 64800s, which is 16 stops more than 1s. Ignoring reciprocity failure (i.e. use Acros or TMY2 and aim for about 2 stops overexposure) and brightness variation through the day, you can take it from there. If you use a traditional film with poorer reciprocity characteristics, it's going to be a complete guessing game.