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Laser Range Finder for Hyperfocal Distance

Discussion in 'Accessories' started by Canonista, Feb 7, 2015.

  1. Canonista

    Canonista Mu-43 Top Veteran

    563
    Sep 3, 2011
    L.A.
  2. jeffg53

    jeffg53 Mu-43 Veteran

    270
    Aug 22, 2012
    Sydney, Australia
    Jeff Grant
    If the lens lacks a scale, what good will distance finder do you? To set hyperfocal, you need distance and aperture markings on the lens.
     
  3. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    :dash2:
     
  4. dwig

    dwig Mu-43 Top Veteran

    622
    Jun 26, 2010
    Key West FL
    No, you can get along without any lens markings just fine. What you need is:

    1. a method of measuring the distance to various objects.
    2. a method of calculating Depth of Field for you lens(es) at various f/stops or a DOF table.
    3. a method of setting the lens to the desired focusing distance.

    #1: The OP's link to a RF is one solution for #1. A simple long tape measure is another. The difference is a matter of convenience. You need to measure the distance to the closest subject that needs to be in focus and then, after using #2, use the measuring device to find an object who's distance equals the calculated hyperfocal distance to serve as a focusing target (see #3, below).

    #2: There are myriads of solutions. Hyperfocal distances are simply special case DOF calculations where the far limit of the DOF is always set to infinity.

    #3: Without a focusing distance scale on the lens you need to find something that is the right distance from the lens, the "hyperfocal" distance, and focus on that either manually or by using AF with "trap focus" enabled (if available on the camera being used).

    All of this is quite simple. True, having a focusing scale and good DOF scale on the lens itself is very convenient. Having these, though, is not a requirement as there are other ways of doing the same thing.
     
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  5. Canonista

    Canonista Mu-43 Top Veteran

    563
    Sep 3, 2011
    L.A.
    Thank you dwig. You've described for the others how I intend to use the device. Perhaps they have a cleverer means of setting focus to the hyperfocal distance, in which case inquiring minds would like to know.

    I use a DOF app on my iPhone to determine the DOF for my particular lens and camera format, which gives me the hyperfocal distance that I need to focus to. I then need to be able to measure the distance to locate that focus point. Where that distance is literally within arms reach, no need for a measuring device, as I can eyeball the distance. Where the distance is farther out, it would be nice to be able to pinpoint the area for ideal focus.
     
  6. KBeezie

    KBeezie Mu-43 Top Veteran

    696
    Sep 15, 2012
    Grand Rapids, Mi
    Karl Blessing
    Does the DOF app you use take into account the crop factor or "circle of confusion" ? (since the size of the micro-4/3rd sensor already gives us a larger degree of DOF than we probably desire compared to larger sensors with the same lens).

    The reason I ask is because if the app is based on 35mm values in the formula, you may be be overcompensating the range needed for the desired effect.
     
  7. jeffg53

    jeffg53 Mu-43 Veteran

    270
    Aug 22, 2012
    Sydney, Australia
    Jeff Grant
    I'll chalk that up to the live and learn column. It does sound like a lot of work to me. Being a landscape person, I'm used to a slower pace, but that would be stretching it. Since I haven't had lenses with scales for years, I use the old technique of focussing one third in to get the best DOF.
     
  8. Canonista

    Canonista Mu-43 Top Veteran

    563
    Sep 3, 2011
    L.A.
    I use an app called Photo Aide. It allows me to select the specific camera body and lens; e.g., EOS 5D with 17-40 f/4L, or GX7 with 12 f/2. So it does compensate for the sensor size. Compared to what I used to use, a paper "slide rule" DOF calculator which is limited to FF 35mm, this app is quite advanced.
     
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