how to calculate long exposure?

[stradibarrius]

Is there a simple method to calculate a long exposure?

[Kevin Crisp]

Are you asking how to compensate for reciprocity failure after you have a meter reading? Or how to get a meter reading in the first place?

[r.e.]

Is there a simple method to calculate a long exposure?

You will find it helpful to do a search on the forum for the phrase reciprocity failure. There are lots of threads specifically on this subject, so it is perhaps best/more efficient to search for the phrase in titles only rather than posts.

[Pawlowski6132]

Its film dependent.

[evan clarke]

Don't be afraid of giving enoigh exposure. I make lots of 10-20 minute exposures and you can't give it too much..EC

[r.e.]

Don't be afraid of giving enoigh exposure. I make lots of 10-20 minute exposures and you can't give it too much..EC

That reminds me that Seattle photographer Chris Jordan, who at one time participated in this forum, made his early 8x10 photographs by exposing colour film for hours. None of that work appears to be on the internet anymore, but it looked rather different from his current work: http://www.chrisjordan.com/gallery/rtn/#car-keys

[Robbie Shymanski]

Experience.

[atlcruiser]

Hi Barry,
Seems like you did not get many good replies

I am not sure what factors are in question for you.

I figure the base exposure and, more often than not, add .5 to 1 stop to that. I then add in filter factor then bellows extension if needed. I have a small printed table to figure reciprocity. I take the above determined exposure to my table and figure final exposure from there. Usually 1-10 seconds or so i go with the table. over that I might double or even triple those times.

I almost never have an issue with overexposure but I have had many issues with underexposure.

[ic-racer]

If you are using Kodak film, the table provided by Kodak is pretty clear. For example "If the [meter] indicated exposure is 100 (seconds), Use this lens-aperture adjustment (+1 stop) or [use] this adjusted exposure time (200 seconds)."

[stradibarrius]

Maybe I should ask this question. If I want to take a shot on a city sidewalk, at night, that has some street lights would I just take a meter reading as normal.
I am asking this as the first part of the question... reciprocity would be part two.