FEB ARTICLE: How to Make a Rangefinder for Minox cameras.

Discussion in 'Minox' started by mtc photography, Feb 1, 1999.

  1. MTC  Photography

    MTC Photography Moderator

    <p>How to use eyes as natural rangefinder and make a calling card rangefinder
    or draw up a rangefinder at the back of a Minox 8X11
     
  2. MTC  Photography

    MTC Photography Moderator

    How to make a Rangefinder for MINOX

    Viewfinder cameras such as Minox GT-E or Minox B are scale focusing cameras, you have to estimate the distance and set the distance scale on these cameras accordingly.
    There are many ways to determine the object distance, from eyeballing to using a separate range finder.
    Do you know that you can make a rangefinder for you Minox subminiatures or Minox 35mm for next to nothing ?
    All rangefinder has two windows, separated by a distance, called the baseline. The longer the baseline, the more accurate the ranger finder.
    One day, I suddenly realized that a pair of human eyes is a natural rangefinder, its base line is between 6cm to 8cm. Why can't I use my eyes as a rangefinder to determine the focusing distance of viewfinder cameras such as Minox GT-E or Minox B ?
    I performed an experiment: I held a ruler with right hand at arms length, first closed my right eye, used only my left eye to align one end of the ruler with a line or an edge of an object, then close my left eye, open the right eye, I noticed that the line now aligned at a distance X to the right of the edge. I noticed that the further the object, the greater the displacement.
    After some simple calculation I found that the image displacement X is given by the following formula :X =E*(D-A)/D; where E is separation of eyes D is object distance, A is arm's length.
    For example let Eye separation =7 CM, Arm's length=60 CM ;
    D=1 M X= 2.8 CM
    D=1.2M X= 3.5 CM
    D=1.5M X= 4.2 CM
    D=1.7M X= 4.5 CM
    D= 2M X= 4.9 CM
    D=2.5M X= 5.3 CM
    D= 3M X= 5.6 CM
    D= 4M X= 6.0 CM
    D= 5M X= 6.2 CM
    D=10M X= 6.6 CM
    D=20M X= 6.8 CM
    Distance Marking
    1 M 2.8 CM
    1.2M 3.5 CM
    1.5M 4.2 CM
    1.7M 4.5 CM
    2M 4.9 CM
    2.5M 5.3 CM
    3M 5.6 CM
    4M 6.0 CM
    5M 6.2 CM
    10M 6.6 CM
    20M 6.8 CM
    I drew these lines on the back of a piece of calling card for use with Minxo GTE I also drew the eye-rangefinder marks at the back of my Minox C.
    A simpler method of drawing this eye-rangefinder marks is the following: mark 1 m 1.2m 1.5m, 2m,2.5m, 3m,4m etc on the floor,with ruler level at arm's length, read off the ruler at points corresponding to the distances. Then mark these on a piece of calling card or at the back of Minox 8x11. ( which
    When use, I hold the Minox or calling card leveled with my right hand at arm's length, align one end with left eye, use right eye to read the distance. When object fall between two marks, set distance proportionally.For example, if the object lies between 1.7 M and 2M, set distance at 1.8M
    After some practice, I now can see two images of calling card from two eyes and read off the distance without closing one eye.
    Try it, it works.
    A Litte Garden

    A Calling Card Range Finder(meter scale )



    1​

    1.2

    1.5

    2

    3

    5

    10

    inf​


    Typical calling card rangefinder for eye distance = 70mm and arm length = 60 cm
    To use, hold card at arm's length, use left eye to align left side of card with object, then
    close the left eye use right eye to measure off the distance ( in meter )
     
  3. Martin,

    <p>

    Like all simple solutions, this one is brilliant! Thank you!

    <p>

    Regards,

    <p>

    Ray Moth
     
  4. Martin,

    <p>

    Last week I had this idea, only to find you'd beaten me to it. I was
    thinking of calibrating the wrinkles on my finger!
     
  5. MTC  Photography

    MTC Photography Moderator

    Minox C with rangefinder in feet
    Minox B with rangefinder in meter
    006RQP-15182584.jpg
     
  6. This is awesome. I've thrown together a page in php that will generate a card with the proper markings, as well as a hyperfocal distance chart. It's at http://www.tomchuk.com/rf_hfd, enjoy!
     
  7. MTC  Photography

    MTC Photography Moderator

    Thomas, your automated program is cool !
     
  8. Martin, you are a genius!
    Thomas, you are a pragmatic genius!

    Thanks to both! this is 2007 and your solutions still works and appreciated.
     
  9. Martin, this is amazing. I just tried this idea out and it is very accurate.

    The hardest thing is holding the card steady.

    By the way, I think I have an accurate way to measure the spacing between the eyes. Stand in front of the mirror, close your right eye, and line the tick mark of a ruler up with the center of your left pupil. Carefully holding the ruler in the same position, open the right eye and close the left eye. Determine which tick mark on the ruler the pupil lines up with. Do this several times to get a good measurement. I believe this method virtually eliminates any parallax error or related artifacts, giving a very accurate measurement of the spacing between the eyes.
     
  10. As I am an optometrist I would like to add a few details on this subject. I tried making this low-tech rangefinder and it seems to work correctly. However, it is urgent to have a certain level of visual acuity on both eyes to be able to read the lines and align them to the distant subject.This will exclude persons with so-called amblyopia, i.e. functionally one-eyed individuals.Furthermore,special attention should be paid when wearing bifocal or multifocal spectacles, as they possibly might distort the image.Such spectacle lenses are usually customized to fit the (converging) pupil distance at near vision, thus creating a slight move of the image,probably creating a major error when reading the measured distance on the RF card.
    And, finally, the easiest way to obtain a correct measurement of your pupil distance is to visit your local optician, who will use a device made for this sole purpose.
    Best regards!
    Lars Giner
     
  11. Following up, I have made a several of these rangefinders.

    I find that old electronic hotel key cards are a good substrate for these devices. I just measure and mark them
    by hand with an indelible marker.

    I currently have two rangefinder cards, one matched to the markings on the lens of my Rollei 25TE and one matched
    to the markings on the lens of my Ricoh 35 ZF.
     
  12. Correction: not 25TE but 35TE, not that anyone will ever find this old thread.
     
  13. I found it :)
    And it is very helpful indeed.
     
  14. So did I and I printed feet on one side and meters on the other and laminated it to credit card size.
    Thanks
     
  15. well if your eyesight is as poor as mine, (forgot watching 3D), you will be in trouble. Me, I still guess....
     
  16. Well, it's over 15 years later and I found this! Very, very clever Martin, and very cool little program, Thomas! Thanks to both!
     
  17. MTC  Photography

    MTC Photography Moderator

    Lambert, thanks for your kind words.
    15 years ago, when I held my Minox C with a rangefinder sticker at arms length to measure distance, I felt a bit uneasy, at that time most people still used film cameras, and no body held film camera that way, people sometimes looked at me, wandering what this guy is doing ?
    15 years later, most people use digital camera, then holding a Minox with rangefinder scale sticker at arms length is just like photographing with a digital camera or a cell phone, no one
    look at me any more. :)
     
  18. Has anyone tried a pocket folding hair comb for this.
    http://www.mensdirect.com/product/Kent-Mens-Folding-Pocket-Comb-82T/tools-hair-brushes-combs
    or
    a Quilling comb like this which is 3.9 inches wide.
    http://www.amazon.com/Quilled-Creations-309-Quilling-Comb/dp/B001689MVI/ref=sr_1_1?ie=UTF8&qid=1410688433&sr=8-1&keywords=paper+quilling+combs

    The pupillary distance could be marked on the comb by looking in the mirror and then measuring the distance.
    Once that is done, then the distance markings(as calculated by the program) be put on the bristles and the bristles between two marks removed.
    The handheld comb would be convenient to hold and fold when not in use.
    If instead of arms length, one enters the length at which the comb is held with the arm straight and comfortable then one can comfortably and effectively use this.
    ..and unlike me, if you have any hair left worth combing- the infinity end of the scale can be used for that as well :)
    I will try and jig this over next week or so.
    Pankaj
     
  19. Nice to see that this thread is still alive.
     
  20. ..and growing :)
    Interesting article about using your hands to assess focal length of the lens to be used.
    http://www.dslrsolutions.net/3298/using-your-hands-as-focal-length-calculator/
    Two hands wide at an arms length is 50mm lens (full frame).
    HTH
    Pankaj
     
  21. fantastic work by both Thomas Achtemichuk and Martin Tai !!
    I printed the card on A4 at 100% but decided to use my smartphone instead of pasting it on a calling card.

    --> Took a photo of the printed card on my cell phone (landscape orientation)
    --> opened the image on my phone, magnified it to match the actual card dimensions (scale on the card)
    --> took a screenshot (on my phone).
    Have to turn off the auto-rotate screen orientation option when using the image/card.

    I was already using a Lightmeter app on my phone ... and now this!
     
  22. MTC  Photography

    MTC Photography Moderator

    Ashoke, combine old tech with new tech, great work !
     

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