RE: Re: [pinhole-discussion] exposure outdoors using meter
Ah Gill...Since he's from New Zealand, he speaks English.You speak American ( pretty well, I might add)...It's kind of like Castilian all the rest of spoken Spanish. have a good day all! andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Guillermo Sent: Thursday, July 19, 2001 12:31 AM To: pinhole-discussion@p at ??? Subject: Re: Re: [pinhole-discussion] exposure outdoors using meter I am sorry my incipient English didn't convey the ideas well enough. - Original Message - From: heys...@xtra.co.nz To: pinhole-discussion@p at ??? 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. Of course it matters, you have to double the exposure your meter gives you as many times as f/stops there are between your meter reading f/stop and the one of your pinhole camera. 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. That's exactly what you should do (if possible). You should also get a reading of the exposure time needed for the nearest f/stop to your pinhole f/stop, your meter is capable of (this so the numbers of doubling is reduced, IOW less multiplications by 2). Mine for instance, is capable of ISO6 (perfect for Ilford Paper rating) and f/128 (good enough for all my zoneplate stuff and at least 1 very wide angle 35mm format camera). Regards, Guillermo 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/ ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/ ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: Re: [pinhole-discussion] exposure outdoors using meter
I am sorry my incipient English didn't convey the ideas well enough. - Original Message - From: heys...@xtra.co.nz To: pinhole-discussion@p at ??? 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. Of course it matters, you have to double the exposure your meter gives you as many times as f/stops there are between your meter reading f/stop and the one of your pinhole camera. 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. That's exactly what you should do (if possible). You should also get a reading of the exposure time needed for the nearest f/stop to your pinhole f/stop, your meter is capable of (this so the numbers of doubling is reduced, IOW less multiplications by 2). Mine for instance, is capable of ISO6 (perfect for Ilford Paper rating) and f/128 (good enough for all my zoneplate stuff and at least 1 very wide angle 35mm format camera). Regards, Guillermo 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/ ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: Re: [pinhole-discussion] exposure outdoors using meter
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/
