RE: [pinhole-discussion] f stops
'tis ok Barb...Senior Gill & I have known each other for a while now andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of bi...@aol.com Sent: Thursday, November 01, 2001 4:20 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] f stops Let's not fight!!! I actually bonded with my husband, a mathematician, using Guillermo's excellent explanation of f-stops. While I do alot of photo, teach it, and also pinhole on occasion, I am a complete voyeur to the list. But I DO read it and think the knowledge that is shared by the likes of Guillermo make it wonderfully exciting! Barb
Re: [pinhole-discussion] f stops
Let's not fight!!! I actually bonded with my husband, a mathematician, using Guillermo's excellent explanation of f-stops. While I do alot of photo, teach it, and also pinhole on occasion, I am a complete voyeur to the list. But I DO read it and think the knowledge that is shared by the likes of Guillermo make it wonderfully exciting! Barb
Re: [pinhole-discussion] f stops
- Original Message - From: "Andy Schmitt" > ow now done get like that... I was just kidding...tho not about the great > explaination part...I'll use it with my class next summer 8o) > Hope your back gets better... Btw are you still making precision PH's for > others? Only when I have WY too much time! :-)) Guillermo
RE: [pinhole-discussion] f stops
ow now done get like that... I was just kidding...tho not about the great explaination part...I'll use it with my class next summer 8o) Hope your back gets better... Btw are you still making precision PH's for others? andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Guillermo Sent: Wednesday, October 31, 2001 9:51 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] f stops - Original Message - From: "Andy Schmitt" > Gill > you have WAY too much time on your hands.. > but a great explaination..I'll save this one > thanks I am sorry Andy, was off, back was acting up, weather lousy, no reason to go out. From now on I will only reply when I don't have WAAAY too much time in my hands, so answers are as un-prolific as possible. Guillermo ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] f stops
- Original Message - From: "Andy Schmitt" > Gill > you have WAY too much time on your hands.. > but a great explaination..I'll save this one > thanks I am sorry Andy, was off, back was acting up, weather lousy, no reason to go out. From now on I will only reply when I don't have WAAAY too much time in my hands, so answers are as un-prolific as possible. Guillermo
RE: [pinhole-discussion] f stops
Gill you have WAY too much time on your hands.. but a great explaination..I'll save this one thanks andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Guillermo Sent: Wednesday, October 31, 2001 10:19 AM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] f stops - Original Message - From: "ragowaring" > > They follow a geometric progression that make the f/stops increase by a > > factor of square root of 2 > > Wow!, is it really that simple. Of course, it all makes sense now and it > will be very helpful. Thankyou for your replies. If it is not too much > trouble a complete explanation would be very welcome Guillermo. Although John Yeo already gave you an explanation, risking being redundant, I will give you another one: In general terms, f/stop is just a ratio that tell us how many times the diameter of the aperture the focal length of your lens is. i.e.. a 50mm lens with an aperture diaphragm opening of 25mm in diameter would have an f/stop of f/2 (50/25 = 2). Another example: a 90mm focal length pinhole camera with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 ) f/stop = focal length / aperture diameter Both Focal length and Diameter must be given in the same units of measure. The amount of light that any f/stop let through is double the one the immediate closed down full f/stop let through. For instance, f/8 let through double the amount of light than f/11 let through and that means the area enclosed by the round aperture opening at f/8 is twice the one for f/11. The area enclosed by a circle is proportional to the square of its diameter (Area = 0.7854 * D^2), therefore, to double the area inside a circle (allowing double the light, meaning opening up 1 f/stop), we need to increase the diameter of the aperture by just square root of 2 = 1.414 We now know the diameter of the aperture from one stop to the next, increase by a factor of 1.414, we also know f/stop = focal length / diameter, therefore the f/stop numbers will increase also by a factor of 1.414 Starting with f/1 (which BTW is neither the theoretical nor practical maximum aperture), to find out the next full stop, just multiply the preceding one by 1.414 and approximate the result as required, like this: 1 = f/1 1 x 1.414 = f/1.4 1.4 x 1.414 = f/2 2 x 1.414 = f/2.8 2.8 x 1.414 = f/4 4 x 1.414 = f/5.6 5.6 x 1.414 = f/8 and so on. As you can notice, the numerical value of the f/stop doubles every other full f/stop, so after you find the first 2 (f/1 and f/1.4) you no longer need to multiply but 1.414 just double the f/stop 2 stops behind. ie. the next stop after f/8 would be equal to double f/5.6 = f/11 (5.6 x 2 = 11), the next stop after f/11 would be double f/8 = f/16 and so on. As an added information, I'd like to mention how to find out intermediate f/stops. When we divide the focal length by the pinhole diameter, most likely than not we get an f/stop number that is not a "full" f/stop. Some paragraphs above I mentioned the following example: "a 90mm focal length pinhole camera with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 )", it is clear that we need to approximate that f/114 to either a full stop, 1/2 stop, 1/3 stop or whatever you like. I usually approximate to the next 1/3 or 1/2 stop, the question becomes: how to know which of these f/114 is closer to? Get your "slide ruler" or your scientific calculator (I use CALC98 http://www.calculator.org/) 'cause we will get some logarithms. To find where f/114 falls with respect to the closest larger full f/stop (larger means smaller numerical value, remember), we just divide f/114 by that larger full f/stop (f/90 in our case), then get the common logarithm (LOG in most calculators, as suppose to Ln) of the answer and finally divide that by 0.15 Let see: 114 / 90 = 1.26 LOG (1.26) = 0.10266 0.10266 / 0.15 = 0.684 The 0.684 means f/114 is 0.684 stops smaller than f/90 , knowing this helps me to know that f/114 is just a bit larger (numerically) than f/90 2/3 (2/3 = 0.666) and also f/114 is just smaller than f/90 3/4 stops (3/4 = 0.750). Knowing all this may be an overkill for most of us, but it doesn't hurt knowing it, anyway. I better stop here. Guillermo ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] f stops
on 31/10/01 3:18 pm, Guillermo at pen...@home.com wrote: > > - Original Message - > From: "ragowaring" > >>> They follow a geometric progression that make the f/stops increase by a >>> factor of square root of 2 >> >> Wow!, is it really that simple. Of course, it all makes sense now and it >> will be very helpful. Thankyou for your replies. If it is not too much >> trouble a complete explanation would be very welcome Guillermo. > > Although John Yeo already gave you an explanation, risking being redundant, > I will give you another one: > > In general terms, f/stop is just a ratio that tell us how many times the > diameter of the aperture the focal length of your lens is. i.e.. a 50mm > lens > with an aperture diaphragm opening of 25mm in diameter would have an f/stop > of f/2 (50/25 = 2). Another example: a 90mm focal length pinhole camera > with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 ) > > f/stop = focal length / aperture diameter > > Both Focal length and Diameter must be given in the same units of measure. > > The amount of light that any f/stop let through is double the one the > immediate closed down full f/stop let through. For instance, f/8 let > through double the amount of light than f/11 let through and that means the > area enclosed by the round aperture opening at f/8 is twice the one for > f/11. The area enclosed by a circle is proportional to the square of its > diameter (Area = 0.7854 * D^2), therefore, to double the area inside a > circle (allowing double the light, meaning opening up 1 f/stop), we need to > increase the diameter of the aperture by just square root of 2 = 1.414 > > We now know the diameter of the aperture from one stop to the next, increase > by a factor of 1.414, we also know f/stop = focal length / diameter, > therefore the f/stop numbers will increase also by a factor of 1.414 > > Starting with f/1 (which BTW is neither the theoretical nor practical > maximum aperture), to find out the next full stop, just multiply the > preceding one by 1.414 and approximate the result as required, like this: > > 1 = f/1 > 1 x 1.414 = f/1.4 > 1.4 x 1.414 = f/2 > 2 x 1.414 = f/2.8 > 2.8 x 1.414 = f/4 > 4 x 1.414 = f/5.6 > 5.6 x 1.414 = f/8 > and so on. > > As you can notice, the numerical value of the f/stop doubles every other > full f/stop, so after you find the first 2 (f/1 and f/1.4) you no longer > need to multiply but 1.414 just double the f/stop 2 stops behind. ie. the > next stop after f/8 would be equal to double f/5.6 = f/11 (5.6 x 2 = 11), > the next stop after f/11 would be double f/8 = f/16 and so on. > > As an added information, I'd like to mention how to find out intermediate > f/stops. > When we divide the focal length by the pinhole diameter, most likely than > not we get an f/stop number that is not a "full" f/stop. Some paragraphs > above I mentioned the following example: "a 90mm focal length pinhole camera > with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 )", it > is clear that we need to approximate that f/114 to either a full stop, 1/2 > stop, 1/3 stop or whatever you like. I usually approximate to the next 1/3 > or 1/2 stop, the question becomes: how to know which of these f/114 is > closer to? Get your "slide ruler" or your scientific calculator (I use > CALC98 http://www.calculator.org/) 'cause we will get some logarithms. > > To find where f/114 falls with respect to the closest larger full f/stop > (larger means smaller numerical value, remember), we just divide f/114 by > that larger full f/stop (f/90 in our case), then get the common logarithm > (LOG in most calculators, as suppose to Ln) of the answer and finally divide > that by 0.15 > > Let see: > > 114 / 90 = 1.26 > > LOG (1.26) = 0.10266 > > 0.10266 / 0.15 = 0.684 > > The 0.684 means f/114 is 0.684 stops smaller than f/90 , knowing this helps > me to know that f/114 is just a bit larger (numerically) than f/90 2/3 > (2/3 = 0.666) and also f/114 is just smaller than f/90 3/4 stops (3/4 = > 0.750). Knowing all this may be an overkill for most of us, but it doesn't > hurt knowing it, anyway. > > I better stop here. > > Guillermo > > > > > > > > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ Thankyou John Yeo and Guillermo for your exhaustive explanations. I new some of it but it seems now I will know all of it (or have I said the wrong thing). Never again shall I want for knowing. Thankyou again. All the best Alexis
Re: [pinhole-discussion] f stops
- Original Message - From: "ragowaring" > > They follow a geometric progression that make the f/stops increase by a > > factor of square root of 2 > > Wow!, is it really that simple. Of course, it all makes sense now and it > will be very helpful. Thankyou for your replies. If it is not too much > trouble a complete explanation would be very welcome Guillermo. Although John Yeo already gave you an explanation, risking being redundant, I will give you another one: In general terms, f/stop is just a ratio that tell us how many times the diameter of the aperture the focal length of your lens is. i.e.. a 50mm lens with an aperture diaphragm opening of 25mm in diameter would have an f/stop of f/2 (50/25 = 2). Another example: a 90mm focal length pinhole camera with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 ) f/stop = focal length / aperture diameter Both Focal length and Diameter must be given in the same units of measure. The amount of light that any f/stop let through is double the one the immediate closed down full f/stop let through. For instance, f/8 let through double the amount of light than f/11 let through and that means the area enclosed by the round aperture opening at f/8 is twice the one for f/11. The area enclosed by a circle is proportional to the square of its diameter (Area = 0.7854 * D^2), therefore, to double the area inside a circle (allowing double the light, meaning opening up 1 f/stop), we need to increase the diameter of the aperture by just square root of 2 = 1.414 We now know the diameter of the aperture from one stop to the next, increase by a factor of 1.414, we also know f/stop = focal length / diameter, therefore the f/stop numbers will increase also by a factor of 1.414 Starting with f/1 (which BTW is neither the theoretical nor practical maximum aperture), to find out the next full stop, just multiply the preceding one by 1.414 and approximate the result as required, like this: 1 = f/1 1 x 1.414 = f/1.4 1.4 x 1.414 = f/2 2 x 1.414 = f/2.8 2.8 x 1.414 = f/4 4 x 1.414 = f/5.6 5.6 x 1.414 = f/8 and so on. As you can notice, the numerical value of the f/stop doubles every other full f/stop, so after you find the first 2 (f/1 and f/1.4) you no longer need to multiply but 1.414 just double the f/stop 2 stops behind. ie. the next stop after f/8 would be equal to double f/5.6 = f/11 (5.6 x 2 = 11), the next stop after f/11 would be double f/8 = f/16 and so on. As an added information, I'd like to mention how to find out intermediate f/stops. When we divide the focal length by the pinhole diameter, most likely than not we get an f/stop number that is not a "full" f/stop. Some paragraphs above I mentioned the following example: "a 90mm focal length pinhole camera with a 0.35mm pinhole would have an f/stop = f/114 ( 90 / 0.35 = 114 )", it is clear that we need to approximate that f/114 to either a full stop, 1/2 stop, 1/3 stop or whatever you like. I usually approximate to the next 1/3 or 1/2 stop, the question becomes: how to know which of these f/114 is closer to? Get your "slide ruler" or your scientific calculator (I use CALC98 http://www.calculator.org/) 'cause we will get some logarithms. To find where f/114 falls with respect to the closest larger full f/stop (larger means smaller numerical value, remember), we just divide f/114 by that larger full f/stop (f/90 in our case), then get the common logarithm (LOG in most calculators, as suppose to Ln) of the answer and finally divide that by 0.15 Let see: 114 / 90 = 1.26 LOG (1.26) = 0.10266 0.10266 / 0.15 = 0.684 The 0.684 means f/114 is 0.684 stops smaller than f/90 , knowing this helps me to know that f/114 is just a bit larger (numerically) than f/90 2/3 (2/3 = 0.666) and also f/114 is just smaller than f/90 3/4 stops (3/4 = 0.750). Knowing all this may be an overkill for most of us, but it doesn't hurt knowing it, anyway. I better stop here. Guillermo
Re: [pinhole-discussion] f stops
Beware of virus ! Ricardo. - Original Message - From: Guillermo To: Sent: Tuesday, October 30, 2001 4:55 PM Subject: Re: [pinhole-discussion] f stops > > - Original Message - > From: "Gregg Kemp" > To: > Sent: Tuesday, October 30, 2001 1:02 PM > Subject: RE: [pinhole-discussion] f stops > > > > I wrote to Philip asking if he was having a problem with his mail and if I > could help. I haven't gotten a reply, but noticed he continues to send > empty messages. > > He's also sending blank msgs to the cameramakers list, also > > and lots of them! > > Guillermo > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ >
Re: [pinhole-discussion] f stops
Yes, all Philip messages are blank. Ricardo. - Original Message - From: Philip Arny To: Sent: Tuesday, October 30, 2001 3:58 PM Subject: Re: [pinhole-discussion] f stops > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ >
Re: [pinhole-discussion] f stops
> So, the ratio between the diameters of consecutive stops is the square root > of two. Because in the F/stop formula, the diameter of the opening is in > the denominator, the actual f number increases by a factor of two, as the > diameter decreases by a factor of two. oops. factor of the square root of two. John
Re: [pinhole-discussion] f stops
Each successive stop is half the area of the previous stop, and therefore lets half as much light in. We know the area of a circle is 2*pi*r(squared). A = pi * R1(squared)A/2= pi * R2(squared) known A = 2 * pi * R2(squared) multiply by 2 pi * R1(squared) = 2 * pi * R2(squared)Since both equations are equal to A, the two equations are equal. R1(squared) = 2 * R2 (squared)Factor out pi R1 = square root of 2 * R2Take the square root of both sides R1 / square root of 2 = R2 Divide by root 2, and get the ratio of the stops. D1 / square root of 2 = D2 Multiply the radii by two, to get the diameter So, the ratio between the diameters of consecutive stops is the square root of two. Because in the F/stop formula, the diameter of the opening is in the denominator, the actual f number increases by a factor of two, as the diameter decreases by a factor of two. John - Original Message - From: "ragowaring" To: Sent: Tuesday, October 30, 2001 12:53 PM Subject: Re: [pinhole-discussion] f stops > on 30/10/01 3:06 pm, Guillermo at pen...@home.com wrote: > > > > >> - Original Message - > >> From: "ragowaring" > > > >>> Anyway, enough of an introduction; could anyone please tell me how to > >>> calculate the natural progression of f stops doubling exposure from one > >>> number to the next, or post a list of these. > > > > They follow a geometric progression that make the f/stops increase by a > > factor of square root of 2 > > > > Need a more complete explanation? let me know. > > > > Guillermo > > > > > > > > > > ___ > > Pinhole-Discussion mailing list > > Pinhole-Discussion@p at ??? > > unsubscribe or change your account at > > http://www.???/discussion/ > > > Wow!, is it really that simple. Of course, it all makes sense now and it > will be very helpful. Thankyou for your replies. If it is not too much > trouble a complete explanation would be very welcome Guillermo. Thankyou > also to Murray for how you calculate the exposure for a given camera; this > method will help me relate one camera to another; also thanks to Bill > Erikson. > > I too don't know what happened to Philip Arny but he has sent me masses of > empty messages. I guess if the cat continues on the keyboard this way it > may come up with one of Shakespear's plays orthe meaning of life, universe, > everything. > > Alexis > > > > > > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/
Re: [pinhole-discussion] f stops
on 30/10/01 3:06 pm, Guillermo at pen...@home.com wrote: > >> - Original Message - >> From: "ragowaring" > >>> Anyway, enough of an introduction; could anyone please tell me how to >>> calculate the natural progression of f stops doubling exposure from one >>> number to the next, or post a list of these. > > They follow a geometric progression that make the f/stops increase by a > factor of square root of 2 > > Need a more complete explanation? let me know. > > Guillermo > > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ Wow!, is it really that simple. Of course, it all makes sense now and it will be very helpful. Thankyou for your replies. If it is not too much trouble a complete explanation would be very welcome Guillermo. Thankyou also to Murray for how you calculate the exposure for a given camera; this method will help me relate one camera to another; also thanks to Bill Erikson. I too don't know what happened to Philip Arny but he has sent me masses of empty messages. I guess if the cat continues on the keyboard this way it may come up with one of Shakespear's plays orthe meaning of life, universe, everything. Alexis
Re: [pinhole-discussion] f stops
- Original Message - From: "TSHACK" > > How would I join the cameramakers list? Is that a newsgroup, or an email > list? Email list, similar to our beloved pinhole list. Here is some info on it: >> Cameramakers mailing list >> cameramak...@rmp.opusis.com >> http://rmp.opusis.com/mailman/listinfo/cameramakers Guillermo
Re: [pinhole-discussion] f stops
> > I wrote to Philip asking if he was having a problem with his mail and if I > could help. I haven't gotten a reply, but noticed he continues to send > empty messages. > > He's also sending blank msgs to the cameramakers list, also How would I join the cameramakers list? Is that a newsgroup, or an email list?
Re: [pinhole-discussion] f stops
- Original Message - From: "Gregg Kemp" To: Sent: Tuesday, October 30, 2001 1:02 PM Subject: RE: [pinhole-discussion] f stops > I wrote to Philip asking if he was having a problem with his mail and if I could help. I haven't gotten a reply, but noticed he continues to send empty messages. He's also sending blank msgs to the cameramakers list, also and lots of them! Guillermo
Re: [pinhole-discussion] f stops
His messages to me directly are blank also. - Original Message - From: Gregg Kemp To: Sent: Tuesday, October 30, 2001 10:02 AM Subject: RE: [pinhole-discussion] f stops > I wrote to Philip asking if he was having a problem with his mail and if I could help. I haven't gotten a reply, but noticed he continues to send empty messages. > > Maybe it's Philip's cat playing with the keyboard(?) >
Re: [pinhole-discussion] f stops
RE: [pinhole-discussion] f stops
I wrote to Philip asking if he was having a problem with his mail and if I could help. I haven't gotten a reply, but noticed he continues to send empty messages. Maybe it's Philip's cat playing with the keyboard(?) Gregg > -Original Message- > From: TSHACK [mailto:tsh...@silver-bayou.com] > Sent: Tuesday, October 30, 2001 12:54 PM > To: pinhole-discussion@p at ??? > Subject: Re: [pinhole-discussion] f stops > > > All of Phil's messages are blank. Just testing to see if > mine will be. > > > - Original Message - > From: Philip Arny > To: > Sent: Tuesday, October 30, 2001 7:11 AM > Subject: Re: [pinhole-discussion] f stops > > > > > > ___ > > 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: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
All of Phil's messages are blank. Just testing to see if mine will be. - Original Message - From: Philip Arny To: Sent: Tuesday, October 30, 2001 7:11 AM Subject: Re: [pinhole-discussion] f stops > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ >
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
> - Original Message - > From: "ragowaring" > > Anyway, enough of an introduction; could anyone please tell me how to > > calculate the natural progression of f stops doubling exposure from one > > number to the next, or post a list of these. They follow a geometric progression that make the f/stops increase by a factor of square root of 2 Need a more complete explanation? let me know. Guillermo
Re: [pinhole-discussion] f stops
Each succeeding fstop is simply the diameter of the aperture divided into the distance from pinhole to film. The specific numbers are traditional and represent a set of diameters that yield aperture areas that are double or half the adjacent one. - Original Message - From: "ragowaring" To: Sent: Monday, October 29, 2001 3:57 PM Subject: [pinhole-discussion] f stops > Hello Everyone > > I have been following your conversations and have found them very > interesting. I am relatively new to pinhole, about two years now since I > first saw what was going on the web. I am a painter and find that > photography makes an interesting a refreshing adjunct to my work. Pinhole > photography is a wonderful way to make images and use your imagination. > > Anyway, enough of an introduction; could anyone please tell me how to > calculate the natural progression of f stops doubling exposure from one > number to the next, or post a list of these. I once saw a list on the web > and have never been able to find it again. I think you will all know what I > mean 5.6, 8, 11, 16, 22, 32 etc up to 1000 or whatever. > > I would find this immensely helpful when calculating exposures and designing > cameras. > > Alexis > > > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.???/discussion/ >
