7 thoughts on “Let’s talk Camera

  1. Hyper-focal distance is the distance between the nearest and furthest parts in the area that you are photographing. This helps keep a landscape photo sharp.

    In researching this subject I have learned that you should focus on the furthest spot of the scene. Then you would manual adjust settings to focus on the nearest area. You want to keep you background sharp. 🙂

  2. Welcome Debbie,

    Good Job – may I add to your comments?

    There are two methods to defining Hyperfocal Distance (HFD), mathematically and practical; I will stay with a practical approach since I don’t do well in math.

    Simply defined, it is the distance in front of and behind the lens’s (POF) point of focus where subjects in the image appear to be in “acceptable focus”.

    In some literature, you will find two definitions for HFD, one defining HFD as acceptable focus between the lens and POF and the other defining it from the POF to infinity.

    We can measure exact hyperfocal distances anywhere from nano-fractions of millimeters to infinity.

    Before we talk about HFD, please recall that any photographic image has only one POF. The camera’s lens achieves the POF by refracting (bending) light “rays” so that light coming from the focused subject will converge, meet, and cross at a specific point, i.e., you sensor. The camera’s operator has the option to select what light they focus (focusing), either from a subject very near the camera or at infinity distance.

    Because of the angles of refraction and distance from the camera, light reflecting from subjects in front and behind the focused subject (and “plane of focus”) will virtually focus in front of or behind the sensor. Depending on the distances and refractory properties of the lens, this light will produce a “circle of confusion” or a blurry subject on the image. Blurriness is directly proportional to the size of the circle.

    Using the camera’s aperture, the photographer can control the circles of confusions’ sizes. Light coming into a lens that is “wide open” (largest aperture) passes through the entire diameter of the lens. To focus this light acceptably the lens creates greater angles of refraction on the edges of the lens and less angulation towards the center. Consequently, light coming through a wide-open lens will produce larger circles of confusion on the sensor for subjects out of the plane of focus.

    When the photographer closes the camera’s aperture to a small opening, it forces the light to pass through only the center of the lens, the same area designed to produce very small angles of refraction, resulting in very small circles of confusion. In many cases, the circles are too small for the human eye to resolve and consequently they infer them to be “in focus”.

    Theoretically, if we could pass light through only the infinite center of the lens (no refraction) we could produce an image with an infinite depth of field. Check out the “pin-hole” camera; it comes closest to demonstrating that theory.

    Other factors affecting the HFD
    • the lenses focal length (magnification power)
    • the quality of the lens (spherical and chromatic aberrations)
    • the nature of light (diffuse vs. point source.)

    Photographers can determine HFD in a couple different ways:
    • select an aperture and focal point they seem appropriate to achieve their goals and using the “depth of field” preview button view the results and adjust if necessary;
    • use a HFD (or depth of field) chart and cross-reference the lenses focal length with available apertures and select setting.

    The chart is more accurate but the photographer can successfully resolve their needs using their preview button.

    In the “good-ol-days”, lens manufactures included a HFD chart right on the lens’s focus ring. There was instant recognition of the required aperture and POF.

    Some modern cameras have a DOF function on its mode wheel. To use it, you put one point of light on the closest point and the other on the furthest point defining the length of the HFD and your camera will select an aperture and POF to accommodate your request.

    Unfortunately, and particularly with the new computer-driven cameras, many “photographers” only consider the aperture as a light-controlling device, if they give it any consideration at all; and may totally ignore its tremendous creative abilities to their failure.

    A serious photographer will strive to understand the relationship between the shutter, aperture, and ISO in terms of Exposure Values then use both the shutter speed and aperture as creative tools in achieving their visualization.

  3. Hi Charlie
    Thank you very much for your input. This helps a lot.

    When I got home from work last night I decided to get out the camera and try some new Shots. Outside my front door on most days I have a beautiful view of the Summit going to Spring Creek and a portion of the Rubies. Although the Rubies were covered by dark clouds I thought that I would be a great picture. Multiple shots later I still did not have the shot I wanted. On one of my shots, I focused in on a tree, and when I down loaded I could see those rings that you have discussed. I had dreams about the hyper-focal distance last night.

    I really had a tough time trying to get that perfect shot. It could have been the lens I was using. It was a Reflex 8/500. When I am at the NASCAR Races in Vegas I can normally capture the jets flying overhead with this lens. So I was hopeful that it would get the shot I was looking for. You know the one we are constantly aiming for.I will use your information for more practice this weekend.

    Thank you very much
    Debbie

    :-)- I like this Blogging

    • Debbie your welcome to upload an example of success/failure 😉 into the creative class album on my web page for my critique, if you like.
      Temporary confusion is often the result when someone is taken out of their comfort zone. Use your comfortable knowledge base as a foundation and keep at least one foot solidly planted there while you add the new stuff.

      Suggestion – set up a camera experiment where your only variable is the aperture; much like the demonstration I gave in class using the measuring stick. I would recommend using your strongest telephoto lens, since the results can be more dramatically read.
      Find a subject where there are other objects near and far (an example would be one tree in a stand of trees)
      Choose only one point of focus. Make an exposure at each of your camera’s aperture settings (remember EV’s, you must also change shutter speed to maintain correct exposure) i.e., make an exposure at f2.8, f4, f5.6, f8… until you reach the camera’s minimum aperture. You will be able to review the changes the aperture makes in the hyperfocal distance in your images.
      Essential – the point of focus remains in the exact same spot for every exposure and the camera must not move (tripod and no zooming) between exposures for this to work.
      Keep after it, it will become intuitive at some point; I guarantee it! If things go mentally blank on you, I will be here to help you escape that circle of confusion – (pun intended 🙂 ) Good Luck

  4. This is great! I will use your suggestion as an added assignment this weekend. I will upload an example for you after this is done. I already deleted the ones from last night. I was disgusted with them. LOL

    I appreciate your assistance. Love the Pun and this class is awesome!
    Can’t wait to learn more.

  5. I am back! I have been down for the last 4 days with that awful bug that is going around.

    I posted some photos for your review in the class folder. I have a few more with the aperture assignment that I have not posted yet. I will give you some time to review the photographs that I have posted today, and I will work on shutter speeds this week.

    Enjoy! 🙂
    Have a great Spring Break
    Debbie

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