Re: Re: 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" <penate@home.com>
> Date: Wed, 18 Jul 2001 08:23:39 -0400
> To: <pinhole-discussion@pinhole.com>
> Subject: Re: [pinhole-discussion] exposure outdoors using meter
>
>
> ----- Original Message -----
> From: <heyseus@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@pinhole.com
> unsubscribe or change your account at
> http://www.pinholevisions.org/discussion/
>
Received on Wed Jul 18 21:59:37 2001