--- karol <dzikamal...@interia.pl> wrote: > hi > i've got an Zero Image pinhole camera > and i've got a question concerning sth called 'reciprocal failure'. > In a instruction added to a camera it's written > that it means that i need to multiply the speed by 2 when it's 1-2seconds, > by 4 when it's 2-4...by 12 when it's more then 10 or sth like this. anyway > it's written in a very simplified way so i'd like to know some details. the > aperture in this camera is 138.
Karol - What you are referring to is Reciprocity Failure. Film is designed to be exposed for a certain period of time, oftentimes 1/10,000 of a second through 1 second. When you go outside of this design, the film will not properly capture the image if exposed for this time period. You need to adjust your exposure to compensate for a time outside of the film's design. Different films have different requirements when referenced in this context, so it isn't as simple as just multiplying the exposure by two (for instance, Tri-X and TMX are dramatically different). Look at the reciprocity failure information on the sheet of paper that comes with the film you use, and adjust according to the directions there. If you do not have that paper, enter "reciprocity failure" and the film type into Google and find it there. Cheers - george ===== Handmade Photographic Images - http://GLSmyth.com DRiP Investing - http://DRiPInvesting.org __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus Powerful. Affordable. Sign up now. http://mailplus.yahoo.com
