Exposure time and f-stop help.

[Ghoste]

I have been wondering recently about using long exposures (bulb) and matching it correctly with the right f-stop. If it's in the evening or at night, and I use a 1 minute or so shutter, how do I know what f-stop to set it at without over/under exposing the film? Anybody have any tips? Thanks alot.

 

[ksmattfish]

It depends on what film you are using. Even films of the same ISO may respond differently when exposure times are longer than 1 sec.

Check out this link for a starting point, and then you'll have to experiment to see what is working best for you. You can search this forum for more info as night photography has been discussed here before at some length.

http://www.fredparker.com/ultexp1.htm

If you go to the manufacturer's website there may be a file you can read about the technical specifications of your film, including how to deal with reciprocity failure during long exposures.