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Needing Help w/ Understanding Hyperfocal Distance

doehillfarmdoehillfarm Member
edited January 2014 in home
I understand WHAT hyperfocal distance is and why it’s used, and I’ve also located several HFD calculators, but I’ve been unable, so far, to nail the spot when focusing the lens. The charts I’ve found provides me with “near” and “far” distances, but that doesn’t tell me WHERE to focus the lens. I'm sure I'm going to experience a "duh" moment when it finally clicks, but until then, I'm still left scratching my head.

I've been attempting this with my Nikon D7000 with a Nikon 28mm 2.8 AIS lens. Although I understand that the crop factor reduces the lens from a wide-angle to a near normal view, I’m pretty sure I should be achieving much better results in DOF/sharpness if I had a better grasp on the hyperfocal calculation, or more specifically, the area in the middle I need to be focusing on. Oh, and, by the way, my newest love is that lens; it makes me giddy just thinking about it.

Ps: Can’t wait for the day when I can afford to upgrade to an full frame camera, but in the meantime, I’m still learning and having fun with what I have. :)

Comments

  • This is a decent calculator and I will use it as a reference. http://www.cambridgeincolour.com/tutorials/hyperfocal-distance.htm

    Make sure you select 1.6 since you are shooting with a DX

    Scenario:

    You are shooting a landscape scene and don't feel like focus staking (or it is not needed) so you want to use H.D.

    You are using a 16mm wide angle lens at f11 (see calculator) so you will need to focus on something 3.8 feet/1.2 meters away.

    Or at 24mm and f11, you will need to focus on something 8.6 feet/1.8 meters

    For your 28mm lens at f11, you will need to focus at 11.7feet/3.6 meters.

    This is best done if the lens has a distance scale. If not, then bring a stick or string with you that is "that" length and then place something at that distance and focus on it.

    I wrote "that" because the length of the stick/string will change when you change f stop. You could use a tape measure as well.


    So that
    doehillfarm said: area in the middle I need to be focusing on
    is the distance I gave a few time above. It changes with focal length and f stop.

    Hope this helps. Don't forget that focus stacking is sometimes better.


    Rudy
  • Neil vNNeil vN Administrator
    edited January 2014
    While focusing on your subject, your DoF (as indicated on the lens or via a DoF calculator on your phone), will tell you how much of the area in front, and behind your subject, will be in focus. Keep in mind that this isn't an exact thing. There's no specific moment something is *in* focus, and shortly after, out of focus. It's gradual … but at some point we say, okay this is in focus enough for us to say it is in focus. (ref: circle of confusion)


    Now, with Hyperfocal distance, You want a certain range to be in focus . (Usually from somewhere to infinity.)

    Let's say it is bright enough that you can use f/8 and you have a 28mm lens on a full-frame camera.

    Using a DoF app on my iPhone:
    While spinning my possible focus distances, my iPhone's DoF calculator says that for f/8 and 28mm, I will be focused on infinity for the first time, when I am focused at 18 ft. Then anything from 8' 9" to infinity will be in focus, with the sharply focused point being 18 ft.

    Using the Dof markings on your lens:
    So with your lens, check the specific DoF markings for your chosen aperture. In this case, let's choose f/8 …. and turn the focus ring so that the infinity symbol is at the appropriate marking on your lens. Then anything from infinity to 9 feet will be in focus. So where did you focus?
    a. Nowhere specific - you used the infinity point and your DoF markings on the lens.
    b. read it off your lens. That's where you are focused most accurately.



    So now I can set my lens to be focused at 18 ft, and walk around the city, and take street photos / snapshots, without focusing … when I guesstimate that my subject is further than 9 feet from me.

    For precaution, you can set your lens to be at f/11 to really be sure (when using a full-frame camera.)
    On your crop-sensor camera, you gain a stop of DoF anyway.
  • Rudy,

    Thanks so much for your explanation. It was the perfectly uncluttered and to the point - just what I needed! Also, I'll bring my tape measure along next time.


    Pam
  • Hi Neil,

    Thanks so much for your input and explanation. I enjoy your tutorials very much as you are one of the few professionals that are able to reduce the complicated into the uncomplicated and I certainly appreciate that.

    Ok, so just to confirm that I'm understanding what you're saying -

    I do not need to focus my lens directly on the 18' mark, using your f/8 28mm scenario.

    That the hyperfocal distance, the sweet spot for the area most in focus, is something to keep in mind to use as a gauge, but not manually focus the lens on - because - I'll have already focused my lens by adjusting my focal ring so that the infinity symbol resides over the line corresponding with my f stop which should give me the greatest dof for that particular shot...or anything else that will be 9' or more from me using the same lens/aperture.

    I can move anywhere using that f stop and lens and I'll be focused from 9' to infinity...so long as I'm mindful of my distance.


    Pam

  • Neil vNNeil vN Administrator
    Exactly.

    I think it feels counter-intuitive, focusing by using the infinity mark on the DoF markings .. instead of actually focusing on something. But that's how DoF works at specific settings (lens / aperture / distance)
  • So....if your lens does not have DoF markings then the only way to get true hyper focal distance would be to focus manually on something the correct distance from the calculation. All my lenses do not have DoF markings and some don't have distance scales.
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