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Medical Forum / General / Vision / September 2007Magnification without glasses?
As a nearsighted person with some mild presbyopia, I only need to take off my myopia glasses to do fine work up close. Lately I am of the impression that the closeup view without my glasses gives me some very mild magnification. Perhaps of the order of 1.1X or thereabouts. Is this "magnification" subjective (contrast between images with glasses and without glasses ) or is it real? Thanks,  SignatureI.N. Galidakis --- http://ioannis.virtualcomposer2000.com/ ---------------------------------------------------------- "There's ALWAYS a mistake somewhere" ----- Original Message ----- From: "Ioannis" <morpheus@olympus.mons> > Is this "magnification" subjective (contrast between images with glasses > and > without glasses ) or is it real? It's relative - your glasses minify. -MT > ----- Original Message ----- > From: "Ioannis" <morpheus@olympus.mons> [quoted text clipped - 3 lines] > > It's relative - your glasses minify. No, without glasses, you can focus at a closer distance than those with "normal" vision, so it is real. I'm very nearsighted and basically have a 5-10X magnifier built into my head when I remove my glasses. :) --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. >> It's relative - your glasses minify. > > No, without glasses, you can focus at a closer distance than those with > "normal" vision, so it is real. No, that isn't optical magnification, it's trigonometry, and it's called "relative distance magnification." Retinal images are twice as big when the object is held half as far away. If you're nearsighted, your glasses still minify, over and above the effects of relative distance mag. The minification is proportional to the prescription and the distance off your eye. Just look in the distance and move your glasses in and out. As you push them away from your eye, the image gets smaller. Minification only approaches zero if you push the lens directly against your eye, as with contacts. -MT On 5/22/07 6:13 AM, in article 8JOdnZuVLOgecc_bnZ2dnUVZ_sCinZ2d@giganews.com, "Mike Tyner" <mtyner@mindspring.com> wrote: >>> It's relative - your glasses minify. >> [quoted text clipped - 14 lines] > > -MT That is exactly what magnifiers do! A magnifier, such as a hand lens, allows you to get closer to the object. In ioannis's situation, he could get the same effect using his glasses and using a hand lens simultaneously. It is easier to just not use the hand lens and not use the glasses as well. Whether you wish to call that magnification or not is just a matter of definition. Bill -- Fermez le Bush--about two years to go. > That is exactly what magnifiers do! A magnifier, such as a hand lens, > allows > you to get closer to the object. Hand-magnifiers increase the image size without having to change distance. They also allow you to get closer if you want to (high plus lenses) but then the two effects are combined - optical and geometric. Changing distance requires focusing differently. This is why so many old people with cataracts get +3.00 or +3.50 adds in their bifocals, so they can focus closer and take advantage of relative distance mag at 12 or 14 inches, instead of the standard 16-18 inches where bifocals are usually set.. > It is > easier to just not use the hand lens and not use the glasses as well. > Whether you wish to call that magnification or not is just a matter of > definition. And the definitions are pretty well established. Still, nearsighted glasses minify, and removing them creates a larger retinal image. -MT I am not an optician, optometrist, ophthalmologist etc., not even a physicist or engineer, but please allow me. It seems you all ignore the fact that vision processing is done in the brain, not in the eye. The image of an elephant on the retina is always minimized, obviously. Not only that, it's also upside down. However, the brain perceives the miniature retinal elephant standing on its head as a full size upright elephant. Our brain learns how to process the retinal image in a very young age. The only time we really notice this minimization is when we switch from no lens to a minus lens or to a stronger lens, but this lasts only for a very short time. In other words, the size of the retinal image is almost irrelevant and is only relative. Of course, a great disparity between the lenses on both eyes will confuse the brain... Ms.Brainy schreef: > I am not an optician, optometrist, ophthalmologist etc., not even a > physicist or engineer, but please allow me. I do...... > It seems you all ignore the fact that vision processing is done in the > brain, not in the eye. Is that true, never thought of it. The image of an elephant on the retina is > always minimized, obviously. Well, why not walk right to this elephant and look him in the eye, enormous image, is it not? Watch out by trying this, you easily could be minimized. Not only that, it's also upside down. No......., realy? > However, the brain perceives the miniature retinal elephant standing > on its head I am a fan of the circus but elephants standing on their head is new to me... as a full size upright elephant. Our brain learns how to > process the retinal image in a very young age. Is that so... > The only time we really notice this minimization is when we switch > from no lens to a minus lens or to a stronger lens, but this lasts > only for a very short time. Dear Brainy, only when the lens is held at some distance in front of the eye. In other words, the size of the retinal > image is almost irrelevant and is only relative. Bullshit of this elephant, when you are standing next to this elephant the size of your head looks a lot smaller to me as the elephant's does Of course, a great > disparity between the lenses on both eyes will confuse the brain... Not always Brainy. Jan (normally Duch spoken) Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) Dear Brainy, Welcome to the "attitude" of the majority-opinion OD. He normally thinks he is a "God", and by that standard, everyone -- the public, the patient, YOU -- are stupid, and must be "corrected" in every way possible, and insulted to boot. Just remember, there are second-opinion ODs who are not like this. They will reason with you and RESPECT you and your goals in life. That is why I post here -- to show respect to people like Steve Leung OD. www.chinamyopia.org Best, Otis > Apparently I have upset the Dutch Goddess. How Dared I! > [quoted text clipped - 64 lines] > > - Show quoted text - On May 22, 7:10 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > Welcome to the "attitude" of the majority-opinion OD. And welcome to Otis--extrapolating from a sample size of one to a total population. That's him in a nutshell. > He normally thinks he is a "God", and by that > standard, everyone -- the public, the patient, YOU -- > are stupid, and must be "corrected" in every way > possible, and insulted to boot. Actually, while his comments to Ms. Brainy WERE rather offensive, he normally reserves his disgust, disdain, AND contempt--quite reasonably--for you. > Just remember, there are second-opinion ODs who > are not like this. They will reason with you > and RESPECT you and your goals in life. > That is why I post here -- to show respect > to people like Steve Leung OD. See question #13 in: http://nbeener.com/NDB_OSB_Qs.txt > Actually, while his comments to Ms. Brainy WERE rather offensive, he > normally reserves his disgust, disdain, AND contempt--quite > reasonably--for you. Jan is a "he"? If so, I apologize for assuming it's a "she". I certainly did not intend to MINIFY him into a female. And vice versa. > > Actually, while his comments to Ms. Brainy WERE rather offensive, he > > normally reserves his disgust, disdain, AND contempt--quite > > reasonably--for you. > > Jan is a "he"? If so, I apologize for assuming it's a "she". I > certainly did not intend to MINIFY him into a female. And vice versa. I actually don't know for certain, but--in Holland--Jan is commonly a male's name. Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) Ms.Brainy schreef: > Apparently I have upset the Dutch Goddess. How Dared I! No problem dear. > Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and > lacks any subtlety. Yes it is sarcastic but in a bad taste? This is what you wrote in sci.med.vision. >> Ms.Brainy schreef: >> >>> I am not an optician, optometrist, ophthalmologist etc., not even a >>> physicist or engineer, but please allow me. >>> It seems you all ignore the fact that vision processing is done in the >>> brain, not in the eye. Most of us here in this sci group are working in the eyecare field, so don't be supprized when somebody working in this particularry field reacts a little bit sarcastic when you stated "you all ignore" and showing your wisdom after that. Jan (normally Dutch spoken) > Most of us here in this sci group are working in the eyecare field, so > don't be supprized when somebody working in this particularry field > reacts a little bit sarcastic when you stated "you all ignore" and > showing your wisdom after that. > > Jan (normally Dutch spoken) You are mistaken. Most of the 750 members of this sci group are NOT working in the eyecare field, but rather people who have/ had questions or problems with their eyes or vision, or just want to expand their knowledge and understanding. This is an outstanding group where professionals are willing to share their knowlege and experience and help those who need advice. I have learned a lot here during my 2 months membership. I don't know what drives those professionals to participate, but even it's an ego trip for some, I am grateful. I am equally grateful for those individuals who participate by sharing their personal experiences, which are sometimes worth more than a professional advice. I did not intend to tell YOU, Jan, things you don't know, but if you read the thread you'll realize that while the retinal image size was discussed, the brain processing of the image WAS ignored. If I am/was mistaken, you can point out where, but rudeness is not a virtue. You are also mistaken characterizing my participation here as "showing my wisdom". My feeling is that this is rather YOUR motivation. I am here first of all to learn and understand my own situation, and I believe that knowledge is power. I contribute when I feel that I have something to contribute. Any objection to this? Ms.Brainy schreef: >> Most of us here in this sci group are working in the eyecare field, so >> don't be supprized when somebody working in this particularly field [quoted text clipped - 7 lines] > questions or problems with their eyes or vision, or just want to > expand their knowledge and understanding. Brainy, there are no members here, this is a non-moderated Usenet newsgroup. Any chance you are a google user? Okay, let's forget it , I have discussed this before Brainy. > I did not intend to tell YOU, Jan, things you don't know, but if you > read the thread you'll realize that while the retinal image size was > discussed, the brain processing of the image WAS ignored. If I am/was > mistaken, you can point out where, but rudeness is not a virtue. Still it was about magnification, not the interpretation of it. Excellent explained by Mike Tyner. > You are also mistaken characterizing my participation here as "showing > my wisdom". My feeling is that this is rather YOUR motivation. I am > here first of all to learn and understand my own situation, and I > believe that knowledge is power. I contribute when I feel that I have > something to contribute. Any objection to this? Not at all Brainy, feel free and accept reactions when you use phrases like "you all ignore etc..." as if the others with the correct answers were brainless fools. Remember Brainy, this newsgroup originally was founded for professional scientifically exchange use only, nowadays it is more used by laymen who are expecting an answer on there questions given by eyecare professionals.(so Otis,beat it) This is not an alt. newsgroup this is a sci.med(scientific.medical) newsgroup about vision. Jan (normally Dutch spoken) > Ms.Brainy schreef: > [quoted text clipped - 41 lines] > > Jan (normally Dutch spoken) Not worthy of a response. Dear Brainy, I agree. Otis > > Ms.Brainy schreef: > [quoted text clipped - 45 lines] > > - Show quoted text - Ms.Brainy wrote: Not worthy of a response. To which Uncle Otie replied: I agree. But, Uncle Otie: you've already established for the record--over 6+ years--and for Ms.Brainy over a much more attenuated period of time-- that YOU don't respond to valid, reasonable questions, either, so ... should YOU be the ultimate arbiter of when responses are and are not called for? I certainly hope not. Here are the questions again, by the way, in case you're in the mood to answer them: http://nbeener.com/NDB_OSB_Qs.txt >Ms.Brainy wrote: > [quoted text clipped - 16 lines] > > http://nbeener.com/NDB_OSB_Qs.txt hehe, i love how you guys are always arguing... It kind of reminds me my little brother and I arguing... in fact it's almost as bad!! (although not quite so terrible). o_O I'm backing Jan on this one, I'm afraid. and she's right afterall... there are no 'members'' on this group. This is a usenet group where anyone can come and go.... and '750' members?? are you jokin' mika?? there's prolly about a ten thousand who come here at the minimum... you jus' don' see 'em all postin... as 4 otis n' neil, i'm not so sure... they're about equal ;P .... *cough*he said ur mum*cough* *cough*are you gonna take that neil??*cough* :-D Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU? > Ms.Brainy schreef: > [quoted text clipped - 53 lines] > > Jan (normally Duch spoken) "Apparently I have upset the Dutch Goddess. How Dared I! Your sarcasm is in bad taste, Jan. It's arrogant, patronizing and lacks any subtlety. I can assure you that I am sharper than you and can beat you in sarcasm, but I have no desire to get engageD in this activity at this point. I have only one question to you, Jan the Duchess: WHAT'S EATING YOU?" Wow... I guess it must be my computer... This post repeats itself many many times!!? Maybe it is a problem with the cookies... > As a nearsighted person with some mild presbyopia, I only need to take off my > myopia glasses to do fine work up close. > > Lately I am of the impression that the closeup view without my glasses gives > me some very mild magnification. Perhaps of the order of 1.1X or thereabouts. It's real. The myopic eye has a larger retinal image, when corrected with glasses it is minified to "normal" size. Dr Judy Dr Judy schreef: >> As a nearsighted person with some mild presbyopia, I only need to take off my >> myopia glasses to do fine work up close. [quoted text clipped - 6 lines] > > Dr Judy Come on Dr Judy,I now you can do better. What about the same myopic wearing contacts? "abnormal size"? Jan (normally Dutch spoken) Dr Judy schreef: >> As a nearsighted person with some mild presbyopia, I only need to take off my >> myopia glasses to do fine work up close. [quoted text clipped - 6 lines] > > Dr Judy Come on Dr Judy,I know you can do better. What about the same myopic wearing contacts? "abnormal size"? Jan (normally Dutch spoken) On 5/22/07 2:00 PM, in article 1179867616.856233.235160@n15g2000prd.googlegroups.com, "Dr Judy" <mpace99@rogers.com> wrote: > It's real. The myopic eye has a larger retinal image, when corrected > with glasses it is minified to "normal" size. So removing eyeglasses allows you to get closer to the object and provides a larger clear image on the retina just as if you used a magnifying glass with the eyeglasses. That sounds like magnification to me. Bill -- Fermez le Bush--about two years to go. > So removing eyeglasses allows you to get closer to the object and provides > a > larger clear image on the retina just as if you used a magnifying glass > with > the eyeglasses. That sounds like magnification to me. The OP was getting close first, then removing his glasses. The image got larger without changing distance. -MT >> As a nearsighted person with some mild presbyopia, I only need to take off my >> myopia glasses to do fine work up close. [quoted text clipped - 4 lines] >It's real. The myopic eye has a larger retinal image, when corrected >with glasses it is minified to "normal" size. The myopic eye has a blurry retinal image. When corrected with glasses, the image is focused and it's size distorted. Things look smaller through glasses, not normal. Use contacts instead of glasses and the shrinking effect goes away (along with a few other distortions). Signature- Mike Ignore the Python in me to send e-mail. >As a nearsighted person with some mild presbyopia, I only need to take off my >myopia glasses to do fine work up close. [quoted text clipped - 4 lines] >Is this "magnification" subjective (contrast between images with glasses and >without glasses ) or is it real? As some others have pointed out, you have it backwards. Your glasses shrink the apparent size of objects. When you take your glasses off, you're seeing the "true" size of the objects. If you wear contacts, this effect disappears. Though so does your ability to easily remove your optical correction for close-up work. Signature- Mike Ignore the Python in me to send e-mail. >As a nearsighted person with some mild presbyopia, I only need to take off my >myopia glasses to do fine work up close. [quoted text clipped - 6 lines] > >Thanks, You don't give enough information, but taking off myopic lenses will provide real magnification from the simple act of holding the object closer. That's all this simple magnification means. If your closest view is 10" and you can use a 1" lens to see a diamond, it's 10 power. If you have say -2 diopters and with them you can still read at 10", that means your ciliary muscles are accommodating by 4di = 40"/10". Now if you take off your -2 glasses, you can now accommodate by 6 diopters. Therefore you can see down to 6 2/3". Objects would look 50% larger than they would at 10". John Polasek |
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