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  1. #1

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    What is a rangefinder?

    Okay... i had to ask. what is a rangefinder (i know it's a 35mm camera) but what does it do and what is it suited for.

    thank you

  2. #2
    gnashings's Avatar
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    Well, a rangefinder is a device used for measuring distance (bear with me - I am not being a smart ass). The classic rangefinders (before radio waves and laser beams vs time methods were introduced) used the very basis of trigonometry - if you know the distance between two points, and the angles at which lines leaving those two points must take to intersect with a third point - you can easily calculate how far that thisrd point is. You may have seen documentaries where soldiers would look through funny looking binoculars with the front elements spread really far apart - those are rangefinders.
    Now, you can apply the same principle to focusing a camera - you just need two points some distance apart that will capture an image, and a lens that will move in a predetermined relationship with them. A rangefinder contains a viewing window and another one that projects an image into your viewfinder. You see the image through the viewfinder, and a ghost image projected via mirrors (usually)by the other viewing port. By moving the focusing ring on the lens, you rotate the second element until the image it projects is lined up with the actual image you see. Because of the predetermined relationship between the two ports and the lens - at that point you are focused.
    In practice you see what you normally see in a camera viewfinder, plus a ghost image - movin the focus moves the ghost image. Line 'em up and you're done. Its really, really simple and very quick! Most RF cameras require less than 2/3 of a rotation of the focus ring to cover their entire range, and you can tell how far off you are by how far apart you are with your ghost image.
    There are many medium format cameras in the RF configuration, by the way, not just 35mm.

    Now, you may ask - if its so wonderful, why aren't all cameras RF's? Well, I don't know, they should be Just kidding!!!
    The adventages of the RF are as follows:
    -very quick focusing
    -no need for a space and weight consuming, not to mention noisy, mirror. This also allows you to generally shoot at slower shutter speeds because the vibrations resulting from the mirror moving up and down are eliminated.
    -as a result of the above, small size and light weight and whisper quiet operation (street photgrapher love them for hteir stealthy ways!)
    -there is no "black out" when the mirror is up, as in an SLR, so you can see everything, all the time.

    The disadventages:
    - you are not looking through the taking lens - so there is something called paralax to adjust for (the fact that you looking through a point removed by a few cenitmeters from the actual lens) as you can imagine, the closer you get, the more off you will be. Most good rf's correct for that by moving the viewfinder as you focus, but a) it only goes so far (its like crossing your eyes after a certain point) and b) it makes the camera not very useful for extreme close up work, also, when you change lenses, you have to use reference lines or separate viewers to adjust for their field of view, where in an SLR - you see what the lens sees - wide angle? you see all that wide angle. telephoto? you see that magnified image exactly the way the film will.
    -many rangefinders use leaf shutters - while they have their adventages, they are generally not capable of the very high speeds of most focal place shutters in SLR's.

    Between those two points, the SLR wins the popularity contest due to its versitility and ease of use (and ease of getting used to various applications).

    OK - I hope that about covers, sorry about the long winded response!

    Peter.

    PS. You will most likely buy one sooner or later. They are cute, handy, charming, have personalities - you fall in love with them... its a sickness!!!

    PPS. Here is a page that you may want to look at - this is a little known camera, but it is a classic rnagefinder layout, and there are many pictures which will hopefully help you make sense of my rambling (look at the picture of the camera with the top plate off to see more less how it works)

  3. #3
    David H. Bebbington's Avatar
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    Google reveals [almost] all:

    http://en.wikipedia.org/wiki/Rangefinder_camera

    Any further questions, get back to me! The article of course concentrates on photographic rangefinders of traditional optical/mechanical design (rotating silvered wedges). There are also large military rangefinders a couple of feet long and more, derivates of these for sportspeople, and all kinds of modern laser, infrared and ultrasound devices (for example, for measuring up rooms in houses).

    Regards,

    David

  4. #4

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    In the wievfinder of a rangefinder you will see everything sharp no matter the distance. The SLR's prewievbutton allow you to see the DOF i.e. the area that looks sharp in the image. Thats vey usefull in closeups, macro work and when shooting a telelens.
    Søren

  5. #5
    cvik's Avatar
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    Here is an image of how it looks on a Leica M6 (rangefinder camera).
    http://www.konermann.net/shade.demo.after.jpeg

    The framelines are always lighter than the rest and is used to compose the image (everything within will be part of the image, everything outside will not). The grey area in the middle is used for focusing. In this area you will see two overlapping images, one is part of the whole viewfinder image, and one is projected on top of it. The image on top moves from left to right when you focus. When the two images overlap the focus is correct.

    and here is an image showing how the camera looks outside: http://www.adorama.com/images/Product/LCM772BK.JPG
    The window to the right is the viewfinder image.
    The middle window (grey) is used to make the frames lighter.
    The left window is the small focusing area.
    The distance between the left and the right window determines the accuracy of the rangefinder. Larger distance = better accuracy.

    Here is an image showing how it works:
    http://www.imx.nl/photosite/leica/te...asics/m6rf.jpg
    The blue line is the whole image.
    The yellow light is illuminates the frames so they will always be lighter than the image.
    The red line is the small focusing image that is projected in the middle.

    When you focus a small mirror is turned slightly so that the projected image moves within the finder.

  6. #6
    gnashings's Avatar
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    Quote Originally Posted by Soeren
    In the wievfinder of a rangefinder you will see everything sharp no matter the distance. The SLR's prewievbutton allow you to see the DOF i.e. the area that looks sharp in the image. Thats vey usefull in closeups, macro work and when shooting a telelens.
    Søren
    I knew I would forget something! Good point.

  7. #7
    Andy K's Avatar
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    What is a rangefinder?

    Fun.


    -----------My Flickr-----------
    Anáil nathrach, ortha bháis is beatha, do chéal déanaimh.

  8. #8
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    Quote Originally Posted by cvik
    The middle window (grey) is used to make the frames lighter.
    I'm confused now. In my FED4, that middle window is the lightmeter. Also, from the picture you pointed showing how it works, it looks like the lightmeter. Am I missing something?
    Last edited by rduraoc; 09-22-2005 at 07:40 AM. Click to view previous post history.

  9. #9
    Marc Leest's Avatar
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    Quote Originally Posted by hanaa
    (i know it's a 35mm camera) ...

    thank you
    Not always: I have a Fuji GSW690 and thats a 6x9 camera (as I am holding it in my picture)

    M.
    We cannot change how the cards are dealt, just how to play the hand...
    Randy Pausch

  10. #10
    laz
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    A rangefinder is a camera many of my generation abandoned in our youth for the flashy SLR; then in wisdom gained from age, returned to it for the shear pleasure of its use and timelessness of it's design.

    I may be primarily a LF kind of guy, but, I'll always keep a rangefinder in my kit!

    -Bob

    P.S. Does anyone else feel so old after reading the question?

    P.P.S Hanaa, no offence intended, I'm so glad you asked and gave the rangefinder folks a chance to discuss their love of what some consider an outmoted technology. I'll go back to LF land now and leave the thread to the experts.

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