Re: [pinhole-discussion] f stops
Beware of virus ! Ricardo. - Original Message - From: Guillermo pen...@home.com To: pinhole-discussion@p at ??? Sent: Tuesday, October 30, 2001 4:55 PM Subject: Re: [pinhole-discussion] f stops - Original Message - From: Gregg Kemp gregg.k...@sas.com To: pinhole-discussion@p at ??? 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 philip.a...@tpl.org To: pinhole-discussion@p at ??? 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
on 30/10/01 3:06 pm, Guillermo at pen...@home.com wrote: - Original Message - From: ragowaring ragowar...@btinternet.com 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] Ilfochrome
thanks for the comment
Re: [pinhole-discussion] f stops
- Original Message - From: TSHACK tsh...@silver-bayou.com 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] Philip Arny
I'm guessing first contact... either an alien life form or the first cries from an artificial intelligence. Hold on, Philip - we are trying to reach you! Actually, I think he has an autoresponder set to reply to any message he receives. I had to unsubscribe him. Hopefully, he'll come home from work, find out what has happened, and be in touch. Gregg He's also sending blank msgs to the cameramakers list, also and lots of them! 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 gregg.k...@sas.com To: pinhole-discussion@p at ??? 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] cat on the keyboard?
I've written him for more information, but in the meantime I've blocked him from posting to the list. Pretty strange... Gregg -Original Message- From: TSHACK [mailto:tsh...@silver-bayou.com] Sent: Tuesday, October 30, 2001 1:33 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] f stops His messages to me directly are blank also. - Original Message - From: Gregg Kemp gregg.k...@sas.com To: pinhole-discussion@p at ??? 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
His messages to me directly are blank also. - Original Message - From: Gregg Kemp gregg.k...@sas.com To: pinhole-discussion@p at ??? 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
[pinhole-discussion] Kudos and a Query
I know I am not alone in my appreciation of the tremendous resources available on this list, Guillermo being a prime example. I always learn something from his posts. Thank you Guillermo, thank you all for your intelligence, artistry and civility. It is always an inspiration. I've already altered an ancient Leonardo to be a close-up camera. I've also been using a PhotoTechnicalGroup (f512) camera with good effect. Well-built, easy to use, only lacks a graphloc back. Does anyone have an email address for Dominique Stroobant? I had communicated via his son Ishmael's hotmail account years ago but would like to get in touch with him again. His 17mm pinhole for Leica thread mount is still my most beloved pinhole, especially for hand-held work. Thanks, Howard Wells http://home.earthlink.net/~sandwell/ Guillermo wrote: - Original Message - From: Gregg Kemp gregg.kemp@??? Guillermo, I don't remember ever seeing your correction formula before. Is that theoretical, or have you tested it? Theoretical, Gregg, as I haven't done any close up work myself. For those (few) people interested in were that correction factor comes from, here it is: ** Pinhole is in most ways, not different than glass lens photography. The lens conjugate equation is: 1 / F = 1 / I + 1 / O where I = distance pinhole to Image plane; F = Focal length and O = distance pinhole to Object being photographed. We can simplify that to: F = I x O / I + O When the Object being photographed is at infinity ( O = infinity ): I + O = O therefore the formula F = I x O / I + O becomes: F = I x O / O and that becomes F = I In other words, when the Object is far away (more than 10 times the distance pinhole to film, in practical terms), the Focal length of the camera is equal to the distance pinhole to film plane. Now, when the Object being photographed is close to the pinhole lens (less than 10 times the distance pinhole to film, in practical terms), the Focal length of the camera is given by (as I stated above): F = I x O / I + O For close up work, then, F has to be substituted (in any of the formulas for optimum pinhole size) by: I x O / I + O For instance, the formula I use is: D = 0.0073 x SQRT( F ) where D = pinhole diameter in inches; F=pinhole camera focal length and SQRT stands for square root of For close up work that formula becomes: D = 0.0073 x SQRT( I x O / I + O ) As I said before, F = I for infinity, therefore I can write the infinity formula as D = 0.0073 x SQRT( I ) Base on that, I can also rewrite the close-up formula as: D = 0.0073 x SQRT( I ) x SQRT ( O / I + O ) There you have the correction factor: SQRT ( O / I + O ) BTW, there are many formulas for optimum pinhole size but all have within them SQRT(F), therefore, the above correction factor should apply fine to all of them. Let's see an example: Our pinhole camera has a distance pinhole to film I = 8 and the Object being photographed is O = 12 away from the pinhole, what size of pinhole is the optimum to use: The optimum pinhole size for infinity is: D = 0.0073 x SQRT ( 8 ) D = 0.020 (aprox) Correction factor is: SQRT ( 12 / 8 + 12 ) Correction factor is: 0.774 Pinhole size for close up work (object 12 from pinhole lens) D = 0.020 * 0.774 D = 0.0155 BTW, all the above is nothing but a sort of bellows correction. For people with mathfobia but that have read this msg up to this point, here are some corrections factor based on how many times the camera pinhole-film distance the object is away from the pinhole lens: less than 10 times = correction factor = 0.95 less than 9 times = correction factor = 0.94 less than 8 times = correction factor = 0.94 less than 7 times = correction factor = 0.93 less than 6 times = correction factor = 0.92 less than 5 times = correction factor = 0.91 less than 4 times = correction factor = 0.89 less than 3 times = correction factor = 0.86 less than 2 times = correction factor = 0.81 less than 1 times = correction factor = 0.70 less than 0.5 times = correction factor = 0.57 Another couple of formulas than may help the original's question poster are: Magnification M = I / O Therefore the Correction factor can also be written as: Correction factor = SQRT [ 1 / (M+1) ] So for instance, if she wanted to photograph an object 2 tall with a camera having 8 between pinhole and film and get a magnification of 2X, she will need to position the object at a distance: O = I / M = 8 / 2 = 4 O = 4 inches and the pinhole size (diameter) should be: D = 0.0073 SQRT(8) * SQRT[ 1 / (2+1)] D = 0.012 The image size will be 4 and therefore the minimum format size needed is 4x5 (portrait) or perhaps -better- 5x7 to allow for some cropping. 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. 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 philip.a...@tpl.org To: pinhole-discussion@p at ??? 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 philip.a...@tpl.org To: pinhole-discussion@p at ??? 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] Zone Plate Focus stringency
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] Ilfochrome
Re: [pinhole-discussion] Zone Plate Focus stringency
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
Re: [pinhole-discussion] f stops
- Original Message - From: ragowaring ragowar...@btinternet.com 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] Zone Plate Focus stringency
Just as a point of reference, if you're going for this look Well, this is my first time attempting something like this. I suspect they will all look the same pretty quickly and get boring. I can't see this one hanging on the wall very long. But, I'm usually heavy into composition, so its nice to have something that took off on its own. I'm trying to figure out how to incorporate a mirror into the image plane to get the image into a mirror-image Rorschach sort of format. you can also get it with a Lomo LC1 - it's a 35mm, with a lens with pinhole-like falloff, and it has an exposure meter that will keep the shutter open until it thinks it's received I just ordered a couple of fully manual Lomos from Free Style Camera. I'll see what it takes to convert those. $12 each, so not a huge investment. I did a search for the LC-1 online, but kept getting the LC-A. Is that the same? Looks like the one Free Style sells for $149. enough light - I've had it stay open 5 minutes. I have photos from halloween in Greenwich Village a few years ago that look very much like this one. I would suspect there is not much variability between photos taken while driving in traffic at night. ;-) Thanks for the info. Dwight
Re: [pinhole-discussion] Ilfochrome
Thanks for the help. I got chemistry from calumet. - Original Message - From: Andy Schmitt aschm...@warwick.net To: pinhole-discussion@p at ??? Sent: Monday, October 29, 2001 3:55 PM Subject: RE: [pinhole-discussion] Ilfochrome Dover Photo in Dover NJ has some stocks can get it for youit isn't cheap... be careful of very out of date chemistry. We had a Ilfochrome course at PV this year that developed issues when we tried to use up some chemistrywe bought new ( lost $$$ on the course). If you want I can check with them on stocks/price...contact me @ aschm...@aandy.org good luck...it's a BEAUTIFUL process... andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of b2myo...@aol.com Sent: Sunday, October 28, 2001 7:52 AM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] Ilfochrome In a message dated 10/27/01 6:38:22 PM, erick...@hickorytech.net writes: I can't seem to find the processing chemicals for ilfochrome in any sort of volumes practical for 'wet lab' home processing. It looks like the chemicals are only packaged in larger quantities designed for roller processers. Anybody with more information? I have a package of 2 one litre bottles (little plastic jars, A, B and C) of Ilfochrome chemistry that I purchased from B H some time ago...maybe a year or so. I would guess they still have it but not sure about the shipping issue. Let me know if you want me to give them a call to find out if they ship towhere are you? leezy ___ 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
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 ragowar...@btinternet.com To: Pinhole-Discussion@p at ??? 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/
Re: [pinhole-discussion] Zone Plate Focus stringency
Just as a point of reference, if you're going for this look you can also get it with a Lomo LC1 - it's a 35mm, with a lens with pinhole-like falloff, and it has an exposure meter that will keep the shutter open until it thinks it's received enough light - I've had it stay open 5 minutes. I have photos from halloween in Greenwich Village a few years ago that look very much like this one. At 4:52 PM -0800 10/29/01, TSHACK wrote: - Original Message - From: Chris Peregoy pere...@gl.umbc.edu To: pinhole-discussion@p at ??? Sent: Monday, October 29, 2001 4:19 PM Subject: Re: [pinhole-discussion] Zone Plate Focus stringency [...] OK, I just got back a test roll from my hacked TLR zone plate camera. This is the only one worth reporting on. Its taken in traffic at night, but I flipped the image because it works better like that. Unfortunately, this doesn't really showcase the zoneplate qualities, unless its to give the lights a softer glow. But it certainly has a lot more life than the other shots on the roll. http://groups.yahoo.com/group/pinholegallery/files/DSZP/zpdashboard.jpg Focal length, 90mm, ASA 100, exposure 4 blocks at 25mph. I'm about to build a rig to use as a mount for the cameras that will fit in my moonroof opening and allow me to also reach up and trigger the shutter open and closed. ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/ --
