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Japanese External Reverse Porro Prism Binoculars. On Line MUSEUM |
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My experience in buying upwards of 1100 pairs of these small Japanese binoculars has been that most needed repairs, regardless of seller’s claims of functionality. The main issue is age hardened optical grease. Most of these binoculars are now between 33 to 63 years old. Oculars commonly seize on independent focus models, and then the ocular barrels unscrew. Similarly, the right ocular and to a lesser degree the focus wheel tends to seize on center focus models. Most binoculars seize at infinity, so the owners may not really be aware of it. I was recently surprised when I received 5 binoculars in a row that were fully functional. But they were quickly followed by 5 in a row that needed repair. In addition to seized oculars, displaced prisms resulting in double images (collimation issues) are quite common. So are dirty lenses and prisms, and missing or loose screws. I now normally assume almost all miniature binoculars will need work. In repairing 800 or so I have developed methods that allowed me to repair virtually all of my miniature binoculars to a functional state that satisfies me. So I will share my procedures. I continue to repair several a week, and occasionally repair full size binoculars for my collections. I only undertake repairs for the collections, not in commerce, and my average repair time is probably 15-20 minutes. If you are hopeless at mechanical repairs, or analyzing how things work or go together, or if you can’t manipulate fairly small items like pins and needles, then you probably will not be capable of the precision mechanical work involved in repairing miniature binoculars. But the methodology for basic repairs is really not too complicated. You do need to acquire some specific tools. For example you must have an assorted set of small “jewelers” screwdrivers with hardened blades. Yes I do own several $100 sets of Starrett® machinist’s jewelers screwdrivers. But the cheap $8 Asian sets also work OK, and I use them all the time. You need the smaller sizes in flat blade (only) with perfect blades: not rounded; not bent; not twisted; not chewed up. The screws on these binoculars are tiny and have often been in place for nearly 60 years. They are reasonably cooperative, but only for screwdriver blades that are a perfect fit. If not, you will destroy the slot and will not be unable to remove the screw or part. As soon as a screwdriver is damaged a little, throw it out. Some of my jewelers screwdrivers seem to have magnetized themselves. Sometimes I like that, sometimes not. Tool demagnetizers cost about $5. You will need tweezers with small ends, or jewelers screw starters, because these screws and especially the set screws are very small and you must orient them precisely back into their threaded holes if you remove them. You probably need a hobby grade lighted magnifying headset with a focal distance of around 6-12 inches so you can see what you are doing. Otherwise you can’t see what is going on with the screwdriver slots. The expensive surgical/dental type is not required. And if you are going to multitask (as in repairing binoculars while watching TV), then get a tray to work over. The tiny screws will drop all the time. They can be nearly impossible to find in your clothing/lap/chair/ rug, even with a magnet. 33 BIS 63 Jähriges verhärtetes optisches Fett ist ein häufiges Problem mit Miniaturfernglasern. Das Ergebnis ist gefrorenes Okular oder ittelfokusmechanismus. Unangepasste Prismen schaffen ein Geisterbild, und dieses ist ein allgemeines Problem. Schmutzige Linsen und Prismen sind auch ein allgemeines Problem. Eingekerbte Prismen werden manchmal gefunden. La graisse durcie pendant 33 à 63 ans est un problème commun. Le résultat est une oculaire saisi. Les prismes déréglés créent une image double. Les lentilles et les prismes sales sont les problèmes communs. Tout peuvent être réparé avec un peu d'effort et d’habilite. On trouve parfois des prismes griffes. |
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You need a set of “jewelers” flat blade screw drivers. Starrett ® are super high quality ones, but the ordinary hobby shop or home improvement store Chinese sets work well enough. |
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You can’t successfully manipulate miniscule fasteners if you can’t see the slots properly. The answer, known to jewelers and the medical professions, is a lighted magnifying headset. I have pictured examples of the extremes available. On the left is an inexpensive hobby grade ENKAY™ brand magnifying lighted headset that I used for a number of years. The light wasn’t so good so I attached an LED light bar with Velcro as an upgrade. A better friend than I might deserve who is a dentist then gave me one of his spare pairs of top end Swiss made Sandy Grendel titanium magnifying loupe headsets to use on an extended loan basis. WOW! A couple grand more makes a big difference. There are in between choices on Ebay. Pay attention to magnification and light and work distance. |
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The 50’s & 60’s optical grease seizes solid, so you will need a butane pencil torch. Nothing else will do the task. DO NOT use plumbing propane torches, blowtorches, or acetylene torches !! Those have far too much heat and are not precise enough. Pencil torches are not always cooperative, or reliable, so to insure you will have a working one, I suggest buying several, with the strategy that at least one will work when you want it to. You will also need a can of butane lighter fuel, and something to light the pencil torches. I use refillable BBQ lighters, but a cigarette lighter or match works OK. |
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To unscrew the ocular barrels without crushing them or gouging them ( never use pliers or vise grips) you need something special. And the rubber strap wrenches don’t work well on anything this small. So you will need something like what I made above. I MIG welded steel rods to 1/4 inch automotive stainless worm gear hose clamps to use as handles. Brazing and silver soldering might also work. These look ugly but work great. They have an astonishing amount of precise grip that is very incremental and doesn’t damage the barrels. These are worth any extra effort to make, or to have someone make for you. Make 2 or more. They may look crude, but nothing I know of works nearly as well. |
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I find these small special shaped Irwin ®Vise Grips® handy when you can almost turn something by hand, but not quite. I don’t usually use the locking action. This tool has smooth jaws. |
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You’ll need a small hobby wire brush to scrub the old hard rubbery optical grease off the ocular threads. |
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Canned air or duster to blow specks or an errant cotton swab hair off the lenses can be handy. |
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This famous name lens cleaner in handy spray bottles of a nice size impressed me with their colorful decal and famous name. It works well, So I bought a case of it on line. You can get various brands of similar lens cleaner on line and at opticians and camera stores. A much cheaper alternative is the home recipe for bulk eyeglass & optics cleaner. Mix up a formula of 75% rubbing alcohol, 25% water, and 2 drops of liquid dish soap. When using any cleaner, use only enough to dampen your cotton swabs. You’ll want to use cotton swabs for cleaning. Cotton won’t scratch, paper products are made of wood and will. These cotton swabs do sometimes leave behind a hard to see strand. So look carefully before tightening up. |
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Diagnostic Tips for Repairing Miniature Binoculars. Diagnosemethoden für Miniaturferngläser. Méthodes Diagnostiques Pour la Réparathion de Jumelles Miniatures. Советы по диагностике миниатюрные бинокль. ミニチュア双眼鏡を修復するための診断のヒント. Consejos Para el Diagnóstico de la Reparación Los Prismáticos en Miniatura. Punte Diagnostici per la Riparazione del Binocoli in Miniatura. |
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Optical Condition of Miniature Binoculars. Zustand Von Optik der Miniatur-Ferngläser. État de L'optique des Jumelles Miniatures. птический состояние. Condición Óptica de Prismaticos en Miniatura.. Condizione Ottiche dei Binocoli in Miniatura. |
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Assessing Optical Quality. Bestimmung der Optischen Qualität. Determination de la Qualité Optique. Оценка качества оптических. 光学品質 の評価\\. Evaluar Calidad óptica. Valutazione della Qualità Ottica. |
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An accepted method of comparing the relative optical quality between binoculars is to observe a star at night through one eyepiece. Binoculars with better quality optics will have less astigmatism, that is, they will allow a sharper focus with less hazing, blurring, or rays around the star when it is in the center of the field of vision, as compared to poorer quality binoculars. This is a comparative evaluation: your evaluation result is that binocular A is better and binocular B is worse( Neither binocular may be particularly good ). Next shift the binoculars so that the star is moved to the edge of the field of view. Binoculars with better quality optics will have less image change across the field of view, or loss of focus, as compared to poorer quality binoculars. And they will have less halo effect. |
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Sharp, so Better |
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Worse |
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Still sharp, so Better |
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Worse |
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Shake & Rattle. Erch ϋ tterung und Geklapper. Secousez et Faites S’entrechoquer. Шумный езакрепленные Детали. 振 ると揺れる. Agitar y Traqueteo. Agitare e Battere. |
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Shake it and it rattles? Pretty good fun for babies. Less good for binoculars. It means parts are loose somewhere, and they shouldn’t be. With these miniature binoculars the most likely cause of rattles seems to be one of the four prisms being loose, or a non captive prism spring. This forewarns future collimation issues and prism damage. The cure is to tighten any loose prism adjuster screws and or reset the prisms. Note: use great restraint on these tiny set screws !!! One wants to “snug” and not “crank down”. Over-tightening will tear the slot off the set screw or will hopelessly round it, or will chip the prism. (note the use of the word “will” and not the word “may”). Be aware that collimating the binoculars may be required after moving set screws. Another likely rattle source is a loose diopter ring, cured by tightening the 3 set screws. Be circumspect about the amount of force you use on these also. Loose lenses in the diopter or in the objective lens pack are another possible source of rattles, though in my experience, they are less commonly encountered, or noticed (even if a bit loose they rattle less). Threaded rings hold these lenses in place. If the rings are loose, they can usually be moved with the fingers or fingernail, or walked in with care using a jewelers screwdriver to push the ring around by its slot. Or make a proper tool of sheet metal. Only tighten to the point of being “snug”. Die von Geräuschen verursacht durch lose teile in den Miniaturferngläsern: lose Prismen, loser Diopterfokus schellt oder löst linsen. Les bruits lâches dans les jumelles miniatures sont crees par les prismes lâches, les anneaux de dioptrie lâches, ou les lentilles lâches. Наиболее распространенные причины плохо закрепленных деталей шумы в миниатюре бинокль: ослабление призм, ослабление диоптрии кольца, или ослабленных объективов. Las razones más comunes para piezas sueltas ruido en miniatura binoculares: flojo dioptrías prismas, anillos, o flojo lentes. |
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A loose prism is a common cause of rattles. There are 4. |
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A loose diopter ring is a another common cause of rattles. |
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A less common source of rattles is loose lenses in the diopter assembly. A capture ring (A) screws in to hold the lenses. |
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A less common source of rattles is loose lenses in the objective lens assembly. A capture ring (A) screws into the inside of the objective barrel to hold the lens. It is usually under a beauty ring (B) that screws onto the outside of the barrel (C). |
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Dirt & Specks &Haze |
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Haze & Fungus |
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Fungus |
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Good Rattles |
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Bad Rattles |
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If you intend to take apart center focus binocular models, be aware that the center hinge screw needs a wider than normal but quite thin slotted blade. You won’t have a proper screwdriver in the kitchen drawer. A blade thin enough to fit the slot won’t be wide enough. A set such as this excellent Brownells® gunsmith screwdriver set can provide the proper size. Or you may be able to modify something like a putty knife by grinding it. |
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Improvised Replacement Eyecups. Ersatz Augenschild. Boucliers d’oeil Improvisés de Rechange. Improviserade Ögonmussla. Improvisados Anteojeras Prismáticos. |
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Eyecups on these small binoculars are frequently lost. Eyeglass wearers sometimes remove them. Or the threads strip (common on the all-plastic eyecups). Since replacement eyecups were never available, one sometimes encounters home machined replacements in Delrin®, other plastics meant for machining, or aluminum or brass. A person with machinist skills, access to a lathe, and an abundance of free time can do this. But to put it in perspective, I do have a lathe, do have Delrin® and aluminum and brass rod of a suitable size, have a bunch of miniature binoculars that need eyecups, but I never quite felt it was worth my time or effort to make eyecups. Anyway, some of these home made replacement eyecups can be rather interesting. |
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My Binocular Parts Game. Ein Spiel Mit Gefallenen Fernglas Schrauben. Un Jeu Avec les Pièces Jumelles Laissées Tomber. Игры поиск сбросили бинокли детали. Un Juego con Pequeñas Piezas Prismáticos. |