Re: [pinhole-discussion] Calculating f-stop for pinhole camera
I never heard of anyone using a slide projector to find the optimal pinhole aperture. Somebody else out there might have heard about it. There are many formulas that various pinhole photographers have used. Many have their own personal formula. I found a formula in a Kodak publication. It seems to give me the most optimal pinhole. And I have experimented with different diameters. Here is the formula I use. The Square root of the Focal Length times 0.007 equals diameter in inches Look in the book, Pinhole Photography, Rediscovering a Historic Technique by Eric Renner which is in its 2nd edition. This book will show you many formulas. I'm sure people in this list have their own formula. Eric Renner also publishes the Pinhole Journal, and is owner of Pinhole Resource, a non-profit organization. The address for the Pinhole Resource is: Pinhole Resource Star Route 15, Box 1355 San Lorenzo, NM 88041 USA Some pinhole photographers do not want the most optimal aperture. They prefer a softer or blurred image. Lonnie
Re: [pinhole-discussion] Calculating f-stop for pinhole camera
From: Rune Tallaksen tall...@alfanett.no Mount the pinhole sheet in a slideframe, place it in a slideprojector. Then by measuring the distance from the pinhole in the slideframe and to the projector screen and the diameter of the projected pinhole on the screen, by means of a formula it was possible to find the exact pinhole size. Anybody out there that know which formula (s) to use?? Do this: Mount your pinhole in a slideframe and project it, focus your projector and measure the pinhole projected diameter. Without altering your projector set up, find the Magnification your projector is set for: mount an empty slideframe in the projector (do not touch the focus) and measure its projected size. Remove the empty slideframe and measure its size. The magnification will be given by: Magnification = Projected slideframe size / Actual slideframe size Your pinhole diameter will be given by: Pinhole diameter = Pinhole projected diameter / Magnification NOTE: use the same units of measure in all the steps. Guillermo _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
Re: [pinhole-discussion] Calculating f-stop for pinhole camera
You can use the formula for similar triangles: (the distance from the lamp to the slide) divided by (the distance from the lamp to the wall) EQUALS (the size of the pinhole on the slide) divided by (the size of the pinhole on the wall) You should be able to increase the accuracy by removing the projector lens and forming the largest image possible on the wall. Jim K www.paintcancamera.com - Original Message - From: Rune Tallaksen tall...@alfanett.no To: pinhole-discussion@p at ??? Sent: Saturday, April 07, 2001 10:04 AM Subject: [pinhole-discussion] Calculating f-stop for pinhole camera When making a pinhole by means of a needle one usually know the pinholesize by the needle size used. I seem to recall that there is another way to do get to know the exact pinholesize but cannot remember the formula used. The method was described as follows. Mount the pinhole sheet in a slideframe, place it in a slideprojector. Then by measuring the distance from the pinhole in the slideframe and to the projector screen and the diameter of the projected pinhole on the screen, by means of a formula it was possible to find the exact pinhole size. Anybody out there that know which formula (s) to use?? Rune Tallaksen Norway ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.p at ???/discussion/
[pinhole-discussion] Calculating f-stop for pinhole camera
When making a pinhole by means of a needle one usually know the pinholesize by the needle size used. I seem to recall that there is another way to do get to know the exact pinholesize but cannot remember the formula used. The method was described as follows. Mount the pinhole sheet in a slideframe, place it in a slideprojector. Then by measuring the distance from the pinhole in the slideframe and to the projector screen and the diameter of the projected pinhole on the screen, by means of a formula it was possible to find the exact pinhole size. Anybody out there that know which formula (s) to use?? Rune Tallaksen Norway
