No one cares whether an obsolete vacuum tube image sensor from 1950 had a rounded outside diameter in integer millimeters or not. Modern solid-state sensors are metric (mostly because they are made in Japan). The "diameter of the glass vacuum tube" is entirely fake as there is no glass tube, and no vacuum. How they "invent" a non-existent dimension really has little relevance. I have no intention of massaging and manipulating a fake number. It doesn't actually exist.
--- On Fri, 4/10/09, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> wrote: From: Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> Subject: Re: [USMA:44530] RE: Reasoable Language (was Metrication US) To: "John M. Steele" <jmsteele9...@sbcglobal.net>, "U.S. Metric Association" <usma@colostate.edu> Date: Friday, April 10, 2009, 1:44 PM The only way to know for sure as to why the numbering was chosen as it was would be to contact the person who first did the research and he is probably dead. Yet we can determine from the result of his work what was intended. Yes, what you say about the full diameter is true, but you need something to start with and the first person to do so obviously did so in rounded metric numbers. These rounded metric numbers were obviously converted to inches and converted to fractions that were rounded to a number with one decimal point. From the chart in the link you provided, you can see that if you convert the strange inch fractions you will get non-rounded metric numbers. But, if you round the metric numbers and then back convert to inches, then round to one decimal place you will get the same inch fraction. You just can't go one way then stop. For example take 4/3 inch and convert it to millimeters. You get 33.867 mm. Now round it off to 34 mm. If you back convert 34 mm to inches you get 1.338 inches. If you round the 1.338 to one decimal place as all the fractions are, they you get 1.3. The closest fractional form to this is 4/3. Try this with the rest of the numbers if you need further convincing. You will never get a round metric number back if you converted a metric number to English units and rounded the final value then took the rounded number and back converted it to metric. For example, convert 15 mm to inches and you get 0.590 551 181 inches. Now round that value to 0.59 inches. Convert 0,59 inches to millimeters but don't round the final answer and you get 14.968 mm, a difference of 0.014 mm. Obviously the person who created the chart just multiplied the strange inches to get a 3 place millimeter number instead of rounding it to the nearest whole millimeter and testing it. If you don't agree with this argument, then can you explain why some engineer chose to work in strange fractions that just happen to be super close to a nice round numbers in millimeters? Would you have? I believe these to be the originally intended metric tube diameters: 6.5, 7.0, 8.0, 8.5, 9.5, 10, 13, 14, 15, 17, 25, and 34 and the inch sizes are the closest approximation: 1/4", 1/3.6", 1/3.2", 1/3", 1/2.7", 1/2.5", 1/2", 1/1.8", 1/1.7 ", 2/3", 1" and 4/3" Test them to verify. Jerry From: John M. Steele <jmsteele9...@sbcglobal.net> To: U.S. Metric Association <usma@colostate.edu>; jeremiahmacgre...@rocketmail.com Sent: Friday, April 10, 2009 1:12:55 PM Subject: Re: [USMA:44530] RE: Reasoable Language (was Metrication US) I have never understood specifying image sensors in that arcane way either. I did find a pretty good explanation. http://www.dpreview.com/learn/?/key=sensor%20sizes Although expressed in unusual fashion it is the outside diameter of of an obsolete vacuum tube sensor. If you convert it to normal decimal inches or millimeters, it is not so round. However, the full diameter was never usable. Around 2/3 that outside diameter was the diagonal of the maximum useful image sensor inside. See table at the end of the article. With technology change, it is a meaningless concept and what matters is in the useful image sensing dimension. Modern sensors appear to have a useful size in metric and a made up tube diameter (the sensor is not glass, and contains no vacuum, so the diameter of a theoretical glass vacuum tube is quite a meaningless concept.) I can't give it any more (or less?) meaning. --- On Fri, 4/10/09, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> wrote: From: Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> Subject: [USMA:44530] RE: Reasoable Language (was Metrication US) To: "U.S. Metric Association" <usma@colostate.edu> Cc: "John M. Steele" <jmsteele9...@sbcglobal.net> Date: Friday, April 10, 2009, 12:29 PM I'm glad you mentioned TVs. I think that video imaging devices are another technology that has lost its metric roots and even by die-hard metric supporters is believed to have originated with pre-metric units. But lie vinyl records, now proved to have originated as a metric product, imaging devices are the same. My post from 18 Jan 2009 questioned the sizes given in inches. They are the most strange set of fractions, including fractions with decimal components in the denominator. A fraction that is an imperial extremists nightmare. They are as far from being rounded in imperial as you can get. Yet when you translate them back to the original millimetre numbers, they turn out to be rounded numbers. Just from the numbers chosen one can deduce what the original designer was thinking. (I'm hoping that John S can explain from an engineering viewpoint what logical reason there would be in designing a product in inches with stange fractions that turned out to be rational metric numbers in disguise if the metric numbers were not intended to be the true dimensions.) Excerpt from my original post: I came across a wikipedia article recently on image sensor format and it had something there that confused me. Towards the end of the article is a TABLE OF SENSOR SIZES. In the first row of the table is the type. It is called out by a size in fractional inches. Except for the 1/4", 1/2" and 1", the rest of these inches I never heard of. I didn't even know some of the fractions stated were possible. I was always taught that inches in fractions followed a pattern where the denominator could only be numbers like 2, 4, 8, 16, 32, and 64. However, this table has the following fractional inches shown: 1/4", 1/3.6", 1/3.2", 1/3", 1/2.7", 1/2.5", 1/2", 1/1.8", 1/1.7 ", 2/3", 1" and 4/3" What kind of inch sizes are these and why are they stated in strange fractionslike these? How do you even say such numbers? I noticed the rest of the article used millimeters to describe the sensor dimensions. So I was wondering if these strange fractions were meant to be inch conversions of millimeters. Does anyone know if this is the case? If you convert all of the inch fractions to millimeters, you get: 6..5, 7.0, 8.0, 8.5, 9.5, 10, 13, 14, 15, 17, 25, and 34. Of course none of the numbers came out exactly as the numbers I show. I rounded them to the nearest 0.5mm. To see if my rounding was biased, I reverse converted the millimeter numbers and rounded the numbers properly to one decimal place and was able to get the same fractional numbers shown above. This lead me to believe that the image sensors were conceived in millimeter units and later changed to fractional inches. Why would someone produce a series of fractional numbers that the average man can't comprehend when a simpler whole number metric series exists and would seem to be more functional? Some of these sensors were based on older model vacuum tubes, such as the 4/3". But was the 4/3" really a 34 mm size? Does anyone know who invented these tubes and why they chose such strange sizes? Why not a sensible fraction like 1-5/16"? This strange set of fractional numbers for the sensor types just seems too strange, so I hoping that someone can provide a logical reason why it was done that way. Jerry From: Stephen Humphreys <barkatf...@hotmail.com> To: U.S. Metric Association <usma@colostate.edu> Sent: Monday, April 6, 2009 8:03:44 PM Subject: [USMA:44459] RE: Reasoable Language (was Metrication US) #yiv370658671 #yiv1286888672 .hmmessage P {margin:0px;padding:0px;}#yiv370658671 #yiv1286888672 {font-size:10pt;font-family:Verdana;} There's the odd exception - eg TV's. Also - isn't Spanish plumbing based on inches for some historical reason? Date: Mon, 6 Apr 2009 12:28:59 -0700 Subject: [USMA:44449] RE: Reasoable Language (was Metrication US) From: slo...@gmail.com CC: u...@colostate..edu To: usma@colostate.edu The Spanish word for inch is "pulgada.." Like most words for inch, it is similar to word for "thumb," which in this case is "pulgar." Of course no Spanish-speaking country uses inches or feet. Naturally the original pulgada, pre-metrication, was not equal to 25.4 mm or the barley-based system you mention. But the word "pulgada" now refers to the 25.4 mm international inch. Similarly the word "pie" means "foot," in both the measurement and anatomy. Stephen Mangum On Sun, Apr 5, 2009 at 7:26 PM, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> wrote: Martin, I agree that the duim is a body part that some people used it to measure things with in the past like the foot. I don't agree that it is the same as the inch. The inch was defined as three barley corns round and dry. Can you tell me the original official definition of the duim? I would suspect that it was not related to barley corns. Thus my point is, the two are not the same. No disrespect was intended. I'm sure we can find a list of units that were used in various countries that have no equivalent to English units. Jerry From: Martin Vlietstra <vliets...@btinternet.com> To: jeremiahmacgre...@rocketmail.com; U.S. Metric Association <usma@colostate.edu> Sent: Sunday, April 5, 2009 3:53:03 PM Subject: RE: [USMA:44374] RE: Reasoable Language (was Metrication US) Jerry, Two things: 1) Please do Han the courtesy of assuming that is command of Dutch is better than yours – the “.nl” at the end of his e-mail address suggests to me that Dutch is probably his mother tongue.. 2) I can vouch for the fact that the word “duim” means both “thumb” and “inch” in both Dutch and Afrikaans (I speak both languages). In English, the word “foot” can either be part of the human anatomy or it can be a unit of measure. In Dutch and in Afrikaans, both the words “voet” and “duim” are units of measure and are also parts of the human anatomy. From: owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf Of Jeremiah MacGregor Sent: 05 April 2009 14:28 To: U.S. Metric Association Subject: [USMA:44374] RE: Reasoable Language (was Metrication US ) … snip Doesn't the word "Duimstok" literally mean "thumb stick"? A thumb and an inch are not really they same thing, even if they are close. … snip Jerry From: Han Maenen < han.mae...@orange.nl > To: U.S. Metric Association <usma@colostate.edu> Sent: Sunday, April 5, 2009 5:54:11 AM Subject: [USMA:44369] RE: Reasoable Language (was Metrication US ) I agree with Bll Potts. Leave expressions like 'inch by inch' or 'not an inch' alone. Those opposed to metric would love it if we wanted to change such things. In the Netherlands a folding measuring stick is called a 'duimstok', which is 'inch stick' in English. I have a wooden duimstok or inch stick with centimetres only on it. I just avoid measuring instruments with dual units like the plague. Just west of of Dublin is the suburb Inchicore, how lunatic it would be to change that to 2.54cmcore, or Sixmilebridge near Limerick to '9.6 km-Bridge'. Of course, the distance to Sixmilebridge is always given in km on road signs: 'Sixmilebridge 10 km'. There is a small place in Ireland called Inch. And people in metric countries should never give an inch to Imperial and/or U.S. Customary in their own environment. That would be very beneficial to metrication. Han ----- Original Message ----- From: Bill Potts To: U.S. Metric Association Sent: Monday, 2009, March 30 22:30 Subject: [USMA:44234] RE: Reasonable Language (was Metrication US ) Pat and John: For years, some of us on this list have tried to be reassuring to the metrication-averse and to also counter some of the stranger statements made by the more virulent opponents of metrication. <snip> -- Stephen Share your photos with Windows Live Photos – Free. Try it Now!
