Thanks for that Guillermo, so as understand it it doesn't matter what the shutterspeed is for you meter reading its the f-stop that counts as it will be converted recipricly anyway.
i was using paper for this exercise and thought that you set the shutter speed to the iso of the neg material used, and make a light reading from there. Thanks again for the info :) > > From: "Guillermo" <pen...@home.com> > Date: Wed, 18 Jul 2001 08:23:39 -0400 > To: <pinhole-discussion@p at ???????> > Subject: Re: [pinhole-discussion] exposure outdoors using meter > > > ----- Original Message ----- > From: <heys...@xtra.co.nz> > > > With your info i got off your website, the sunny16 + iso exposure rule, > > when using a meter do you use the meter reading and the iso=shutterspeed to > > calculate your exposure? > > Did you mean "iso+shutterspeed"? if so, here is the answer (BTW, I may > overexplain, my excuses in advance for doing that): > > When I use a meter, I set it for the ISO of the emulsion in use, then I take > a reading and obtain a "pair of exposure values", f/stop+shutter_speed, that > is. Then I translate that pair of exposure values to an equivalent pair for > when the f/stop is the one of my pinhole camera. For instance: My pinhole > camera is f/512, a meter reading gives me f/45 @ 1/30, there are 7 stops > between f/45 and f/512 (45 -> 64,90,128,180,256,360,512), therefore the > equivalent pair of exposures values f/45@1/30 for my pinhole camera would be > f/512 @ (1/30 +7stops). 1/30 +7 stops is equal to doubling the time 7 times > 1/30 -> 1/15, 1/8, 1/4, 1/2, 1, 2, 4secs, my pinhole camera exposure should > then be f/512@4 seconds plus any reciprocity correction needed for the > emulsion in use. > > > I used it to teach a class but had varying results, although i have > > suspitions that the cameras were dodgy. > > I just need a little clarification on this. > > But the ones that did turn out on my camera and one other were as near > > perfect as i could have hoped. > > > > The only way to get consistent results from many cameras is if you have > measured the pinholes of all the cameras in a relatively accurate way, which > in turn allow you to know the f/stop of your cameras. Obviously, pinhole of > all the cameras should be clean, free of burrs and obstructions. > > > Also if you have any info on Pinhole under studio flash conditions i would > > really appretiate it, i had a formula worked out which worked well for my > > camera but had limited success with the others. > > I used > > exposure = difference of stops from meter reading to camera aperture x 1.5 > > If you have any suggestions to improve this, that would be great. > > Here is what the Laws of physics MANDATE: you should give a number of flash > "pops" equal to 2 multiplied by itself a number of times equal to the > difference of stops. For instance, stops of difference = 5, number of > "pops"= 2x2x2x2x2 = 32 pops > And then you will have to give few pops more to compensate for INTERMITTENCY > (sp) EFFECT which for the above example would state: an exposure of 32 pops > of low power flashes (flash-A) is less effective that one single pop of a > flash-B with a power equal 5 times the power of flash-A. > > If shooting negative material, you may obtain printable results for up to 4 > stops of difference when using your formula, but for the more stops of > difference the more unlikely you will. > > Hope it helps, > > Guillermo > > > _______________________________________________ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ >
