rogart63

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    rogart63 reacted to clockboy in Loupes   
    Generally the stronger the magnification the shorter the focal length. Therefore you will need various lopes. I have found this article on the web which explains better than I could.
    PS I also use a microscope for the really close stuff such as hairsprings.
     
    BASIC TECHNICAL STUFF: MAGNIFICATION AND WORKING DISTANCE
    The following applies to simple lenses, including all jewellers loupes. The following does not apply to 'surgeons' magnifiers which are made of two small telescopes. 
     
    THE 14 INCH RULE
    Some magnifiers are marked with the magnification, some are marked with the focal length (working distance) in inches. 
    The focal length (working distance) is the ideal distance between the lens and the object, not too close (or the lens won't magnify) and not too far (or the image appears wavy). And if you hold the lens MUCH too far from the object, the image will appear upside down.
    Most people don't understand 'focal length' and so when they see a '3' (for some reason eyeglasses are often marked like this) they think it means "3X magnification" when it really means "three inch focal length".  Matters are made worse by the fact that many manufacturers are 'approximate' in their calculations, you can measure the working distance of a 1" magnifier and find it is nearer to 2".  
    So what is the relationship between focal length (working distance) and magnification?  Here is the way I used to calculate it.
    If you take a 'normal' working distance for reading to be 14", then a 7" magnifier brings you twice as close = 2X magnification. This '14 inch rule" is what I used in my catalogue to calculate magnification up until 2011, and the arithmetic works out like this:

    1.5 inch = 9.3X magnification 
    2 inch = 7X magnification
    2½ inch = 5.5X magnification 
    3 inch = 4.5X magnification 
    3½ inch = 4X magnification 
    4 inch = 3.5X magnification
    5 inch = 2.8X magnification 
    6 inch = 2.3X magnification
    7 inch = 2X magnification
    8 inch = 1.8X magnification 
    9 inch = 1.5X magnification 
    This '14 inch rule" is the way I used to calculate it; it is also the way our manufacturer of watchmakers eyeglasses calculates it, the numbers convert nicely from inches into more-or-less whole numbers for 'magnification', as you see from the chart above.
    THE 10 INCH RULE
    Then I discovered that according to the almighty Wikipedia the 'normal' working distance for a lens is 10 inches. This is rather neat because (as you will see if you read the extra-technical stuff below) 10 inches is about 25cm, and 25cm X4 = 1 meter (near enough), and physicists use 1 meter as the definition of 'standard' focal length (not very practicable as a 'working distance')...but don't worry about that, all you need to know is - the way I calculate magnification now falls in line with the 'official' method you find online, like this:

    1 inch = 10X magnification
    2 inch = 5X magnification
    2½ inch = 4X magnification
    3 inch = 3.4X magnification
    3½ inch = 2.8X magnification 
    4 inch = 2.5X magnification
    5 inch = 2X magnification
    6 inch = 1.7X magnification
    7 inch = 1.5X magnification
    8 inch = 1.3X magnification
    9 inch = 1.1X magnification
    These numbers aren't as good as the old "14 inch rule". For instance, both a 3½ inch and a 4 inch lens have a magnification of about 3X. And both a 5 inch and a 6 inch lens both have a magnification of about 2X. And I get customers who think I'm being evasive when I describe two eyeglasses as being, "about the same magnification". 
    If you would like to try out different focal lengths and magnifications to see how they convert (using this "10 inch rule"), go to my conversion program, click here (it's an Excel file, so you might have to select OPEN).
    WHAT DO OPTICIANS AND SCIENTISTS SAY?
    This entire system of magnification being "how many times bigger than normal" (or "X magnification") mystifies opticians. What is 'normal'? It varies from person to person. For an optician, a lens has a focal length - a number that can be calculated, not a 'magnification' relative to normal'. If you really want a definition of 'normal' you should use the standard distance (focal length) used by physicists: 1 meter. But by this definition you need awfully long arms to hold a 'normal' lens in one hand and a book one meter away in the other hand. 
    Also, the human eye often requires more than 'just a bit of help with magnification'. That is why you go to an optician - because he has spent years studying optics rather than reading an entry in Wikipedia. I am not an optician and my knowledge of the maths of optics is shamefully poor. I will, however, attempt to guide you through the mysteries of magnification in the following few paragraphs. They are a bit technical, so you may prefer to skip them and go straight to 'CONCLUSION'..

    ADVANCED TECHNICAL STUFF
    The following calculations apply to simple lenses, including all jewellers loupes. The following does not apply to 'surgeons' magnifiers, which are made of two small telescopes, or to microscopes.
     
    FOCAL LENGTH, DIOPTRES AND MAGNIFICATION
    "Working distance" is the same as focal length. 
    The focal length is the distance you hold the lens from the object that gives the most magnification and the clearest image; it is also the point at which a distant bright object (e.g. the sun) makes the smallest image (e.g. to make a fire using the sun); it is also the distance at which you can project a bright scene onto a surface (stand in a dimly-lit hallway and project the image of a bright window onto the wall). Try it with any magnifier, the distance from the lens to the object will be the same with each of the above experiments, this is the focal length of the lens. In practical terms we can also describe this as, "the [ideal] working distance." 
     
    'Dioptre' is the reciprocal of the focal length. 
    The dioptre is the measurement used by opticians and lens-makers, it is more reliable than defining magnification as "how much larger than normal an item appears". This is because "normal" varies from person to person (there is no rule that says you have to hold a book ten inches from your eyes!). 
    'Dioptre' is the reciprocal of the focal length. To write this as a formula, call the magnification M (if you prefer you may say P for power rather than M for magnification...but let's keep things simple) and the focal length f (in meters not inches) which gives: M = 1 / f. 
    But this 'magnification' is based on the physicist's 'standard' focal length of 1 meter. If you assume 'normal' working distance for a human holding a magnifier to be a quarter of a meter (about ten inches*) then you must divide by four. The formula for converting dioptre to magnification is therefore M = D / 4. * this is not because there is anything special about 10 inches, merely that it works nicely as a number, because 10 inches is almost 250mm = 0.25m, which is why we divide by four. This is one of two accepted formulae for calculating magnification. 
    The above formula works beautifully for small powerful magnifiers such as jewellers loupes and small readers. For instance, for a magnifier with a focal length of 30mm: 1 / 0.03m / 4 = X8.33 magnification. But this formula is based on two assumptions:
    a) that the object is held at the 'ideal' distance from the lens (its focal length) to give maximum magnification
    that the lens is held very close to your eye so that your eyes are focusing into the distance (at infinity).
    This doesn't work for large lenses with long focal lenses. For instance, if we apply the formula to a large reading magnifier with a focal length of 500mm we get 1 / 0.5m / 4 = X0.5 magnification. Oh dear, that can't be right, it looks as if it reduces rather than magnifies. In a sense, this is true, if you place an object 500mm from the lens and hold the lens against your eye, it won't magnify at all. What you must do is move the object closer than 500mm from the magnifier (the magnification will be less) then move your eye away from the magnifier. Your eyes are no longer looking into the distance (infinity) but are focusing closer. 
    To allow for this there is another accepted formula for calculating magnification: D / 4 + 1. 
    Applying this to our magnifier with a 500mm focal length, we now get 1 / 0.5m / 4 + 1 = magnification X1.5, which is more plausible. 
    All of these figures for 'magnification' are approximate, and there are many reasons for this. 
    Firstly, it depends which formula you use (see above). Secondly, if the result looks clumsy (e.g. a magnification of X8.333) the supplier will round it up or down. Thirdly, how much closer than your 'normal' reading distance an object appears depends on what is 'normal' for you. Fourthly, if you use the "ten inch rule" (see explanation above, and also my magnification calculator) instead of the formula, you get slightly different figures because ten inches isn't exactly 250mm. Fifthly, even when you go to the trouble to measure the focal length and calculate the magnification, you will often find that what is printed on a magnifier is simply wrong. 
    If you think this is all a little confusing, it is. In fact, it's very confusing. For instance, if you place the object too close to the lens (less than its focal distance) the magnification will be less, and if you hold your eye away from the lens, the magnification will appear to be more. 
    One nationally-known company specialising in magnifiers consistently used the first formula, above (D / 4). As a result, most of their magnifications were listed as being less than one, indicating that they made everything appear smaller rather than larger. Then they re-printed their brochure, listing magnifications consistent with the second formula, D / 4 +1.

    The famous optical company Zeiss produce a standard 10X jewellers loupe with two lenses, they fold out and can be used individually or on top of each other (the two magnifications simply add together). At one time they quoted the magnification of the two lenses as 6.66X + 3.33X = near enough 10X when used together; then it became 6X + 4X = 10X; now they label it 3X + 6X = 9X. I don't believe they have been changing the lenses each time, the slight variations are due to the way they calculate 'magnification' then round the figures up or down. 

    IF YOU WEAR SPECTACLES
    If you wear spectacles, should you keep them on whilst using a magnifier?
    When using a large magnifier (e.g. for reading) the answer is: yes.   I assume, here, that you need a magnifier because the print / map / mark is exceptionally small and you need that extra help in addition to your spectacles.
    When using a small magnifier (e.g. a jeweller's loupe or watchmaker's eyeglass): do whichever is the most comfortable, but you must keep the magnifier as close to your eye as possible. 
    The only time you may wish to think about whether to keep your spectacles on or take them off is if you are wearing a magnifier over your head (a binocular headband magnifier), they can be used with or without spectacles, as follows:
    If you are short-sighted (you have difficulty in seeing far objects, your spectacle lens prescription has a power beginning 'minus' ) you will notice that when using the magnifier without your spectacles the working distance is less than marked on the magnifier. If you are very short-sighted you will also notice that if you don't use a magnifier you can focus on very close objects - you have magnifying eyes for close objects (the only drawback being that you can't focus on far objects). The consequence is that with a binocular magnifier you may choose between two magnifications: one (weaker / further away) when you wear the magnifier over your distance spectacles and one (closer / stronger) when you wear the magnifier without spectacles, whichever you find the most comfortable.
    If you are long-sighted (you have difficulty in seeing near objects, your spectacle lens prescription has a power beginning "plus") you will notice that when using the magnifier without your spectacles, the working distance is more than stated on the magnifier. If you are very long-sighted you will also notice that a low-power magnifier doesn't actually magnify at all, it merely brings close objects into focus at a 'normal' viewing (e.g. reading) distance, which is exactly what your reading spectacles do: they are low-power magnifiers. The consequence is that with a binocular magnifier you may choose between two magnifications: one (stronger / closer) when you wear the magnifier over your spectacles and one (weaker / further away) when you wear the magnifier without spectacles, whichever you find the most comfortable.
  2. Thanks
    rogart63 got a reaction from Ishima in seiko 11a mainspring?   
    https://www.ebay.co.uk/itm/Seiko-401-110-Mainspring-Ressort-Muelle-Zugfeder-Molla-1104A/162358367342?hash=item25cd50146e:g:kmAAAOSwZQRYepH-
  3. Thanks
    rogart63 got a reaction from chadders1966 in Omega f300   
    That's not a quartz watch  That's a "hummer" tuning fork movement. Not sure a linefree box will be so good on this?  ESA 1260 is that the daydate model? 
    Bad coils can be one problem. They are very difficult to work with as you need a microscope and now what you are doing.  There are a few watchmakers that service this watches. Check electricwatches .....out. 
     
  4. Like
    rogart63 reacted to WatchMaker in Valjoux 7734 hand sizes   
    This link... https://rwg.cc/topic/130110-valjoux-72-hole-sizes/ ... details the 7734 with hand sizes different from those at ranfft. Any use?
  5. Like
    rogart63 reacted to MrRoundel in AS1240 for Seeland, with Incastar regulator   
    Recently I bought an AS1240 for parts for another I was repairing. Prior to receiving it, I took another look at the images and thought that the dial had been bent somehow while removing it from its case. It turns out it was a Curvex style dial. In and of itself, I thought that was pretty cool. It also had a rather strange regulator that I hadn't seen before. Then today I was looking at one of Jendrtizki's books and saw an image of this regulator, calling it an Incastar and explaining how it works.  He said that movements using it were essentially "free-sprung".
    Hours later I do an internet search for Incastar, and what comes up at the very top? A thread by rogart63 on WRT. Very cool indeed, considering rogart63 helped me out with a few watch parts I needed last week. Thanks, rogart63!
    Another thing that is rather interesting about this movement is that it has 19 jewels. I spent a few minutes searching for other 19J AS1240's, but didn't turn up any. While rarity may not equate to value, it seems like it's a rather rare configuration for the model. I'd be interested to hear about others from others. It's rather sad that the case is no longer with the movement. It was probably gold and got melted, much like the one that rogart63 speculated about in his thread from a few years ago (below).
     

  6. Like
    rogart63 reacted to Chopin in Acrylic crystal fitting help   
    I have ordered a high dome without tension ring and see if it works. Fingers crossed!
  7. Like
    rogart63 got a reaction from Chopin in Acrylic crystal fitting help   
    ´Not sure. Feels like the non tension ring low dome is lower and the high dome is a little higher then the ACT crystal. If i would guess i would say high dome. Think cousisnuk have a document of the crystals. 
  8. Like
    rogart63 reacted to jdm in Faulty pallets   
    This is from a brand new 4R36 watch that stopped randomly and had an horrible pattern. Lubricating balance pivots and pallets improved the pattern a lot, but it would still stop easily. When testing the pallets on the escape wheel it had a slight tendency to "spring" to the exit positions, so I replaced it with another from the spares box. Much better, crossing fingers it seems to be running reliably, and the pattern and amplitude are almost perfect.
    I can kind of see that a stone is so slightly slant ?!?
     


  9. Like
    rogart63 reacted to Folkvisor in AS589   
    I got the screw off but I have another problem totally new to me.
    I had a strange chemical reaction in my ultrasound tub. A lot of brownish yellow material appeared from nowhere and has really made a mess of many of the parts.
    I've never had this happen before. I'm not sure if has something to do with a chemical reaction between the cleaner I use and some of the metal parts on the AS589 or what. 
    Has this happened to anyone else?
    Very strange!
     
  10. Like
    rogart63 reacted to Ullas in ETA 963.125, Fake Rolex - Replacement or repair   
    Thank you. As i did mention, its not the monetary issue here, but its more of a memory to my friend of his father. 
    Thank you sir. I guess I'll keep it quartz as much as possible.
    Didn't quite understand in what way this was meant sir, but if it was regarding me selling this watch, you can see its in a very rough shape for anyone to buy it. And I definitely don't want to add to the menace of fake Rolex watches that exist here already.
    Ill take that into account next time sir. I was just being honest. Yes, the question was closed within few hours of me posting it there. More important for me than the "Fake Rolex", even though I initially mentioned it, is to get this watch running for my friend. Its a kind of a gift he recieved from his father just about four days before his sudden demise, so it holds a special place to him. Doing repairs as a hobby, I have decided not to take money for this work from him.
     
    Thank you all for your response. The exchange chart mentioned only an ETA 963.124 and not a 125. I was bit doubtful, so asked here. 
  11. Like
    rogart63 got a reaction from Chopin in Acrylic crystal fitting help   
    Depends on the size i think. Measured a 307 ACT crystal and the edge was 0,52 mm thick. 
  12. Like
    rogart63 got a reaction from jdm in Automatic winder help/explanation   
    Not sure but it looks like the finger is upside down. Almost sure. If you have it like that it won't work. 
  13. Like
    rogart63 reacted to vinn3 in Hello from south Sweden!   
    yes a famous ship,  took in water thru the gun ports,  I was refuring to the town in the Swedish part of Finnland.  vin
  14. Like
    rogart63 reacted to pmlapl in Frustrated Seiko 7s26A search.   
    Thanks for all the help. I went for the eBay 7s36 rotor. The seller is confident it will work. 
    mousekar, I'll keep you in mind if I need any other parts.
  15. Like
    rogart63 reacted to vinn3 in Hello from south Sweden!   
     
  16. Like
    rogart63 reacted to Tipsy in Hello from south Sweden!   
    I'm from Skåne.
    It does seem like more and more Swedes are getting into the watch hobby, in one form or another.
  17. Like
    rogart63 got a reaction from Tipsy in Hello from south Sweden!   
    Välkommen landsman . 
    Great to see some fellow Swedes here. What part of Sweden? I am from Småland. 
     
  18. Thanks
    rogart63 got a reaction from Maze in Baume &Mercier alarm clock   
    Make sure the movement tabs has good contact with the piezo in the caseback. You  maybe need to bend it out a little. How did you mount the hands if you didn't now the alarm hand was in the right position? 
  19. Like
    rogart63 got a reaction from jdm in Copper plating damage on Speedy   
    That is probably corrosion due to a bad gasket or something done by a previous watchmaker. I don't think it will spread. But you should need to look over your gaskets. The little i can see i can see that it's in bad shape. Maybe have a service done or at least a check. 
    Omega has coating called rhodium. 
  20. Like
    rogart63 got a reaction from VWatchie in Hello from VWatchie in Stockholm, Sweden   
    Hej Vwatchie 
    Kul med en landsman.Välkommen. There are more people from Sweden in here i think.  Nice mod you have done . Have worked on some Vostok to. But not that fond of them. But parts are cheap and they are real workhorses. But would love a Vostok swing lug. I fixed a Vostok recently that i managed to get waterproof and the owner said he take i diving this summer  
     
  21. Like
    rogart63 reacted to ro63rto in The Art of Making a Nixie Tube   
    Always been fascinated by these but could never justify the cost. One day maybe.
     
     

  22. Like
    rogart63 got a reaction from Pip in Loose sub-dial hands Seiko 7A38   
    The left one looks a little damaged . Pressed them to far down?  Not you but the tinker that was there before?  Or coming from an other watch?  As they don't look the same on the back? 
  23. Thanks
    rogart63 reacted to WatchMaker in roamer   
    A really useful source of information is Christian aka watchguy.co.uk
    Check out https://watchguy.co.uk/cgi-bin/library?action=show_brand&brand=Roamer and you'll see he's worked on three 522's and taken photos along the way.
    I've worked on a Limelight and Searock with 522's in the recent past so may be able to help in the unlikely event you hit an issue. 
  24. Like
    rogart63 reacted to rodabod in Tissot 28,5-621 mainspring question   
    Probably best replacing entire spring with one with a built-in auto bridle as you have done.
  25. Like
    rogart63 reacted to JohnR725 in Tissot 28,5-621 mainspring question   
    On some early automatic watches the mainspring was two pieces. The spring itself that would look like conventional spring and a shorter spring that was on the outside provided the slipping and some place for the mainspring to attach.  Your shorter Slipping spring looks something homemade or basically it just doesn't look right? Fortunately today when you get your mainspring it's one spring and you don't have to deal with that outer peace that's hard to find and a pain to get into the barrel.