A hyperfocal distance scale on a hasselblad 100C/M
I have been sailing off and on since I was 9 years old.
I got my first boat when I was 13 and have owned one ever since – or at least until my ex-wife ran the Swan up on the rocks at Cuttyhunk.
OK. Let’s try and get over that.
In any event, when I was about 15 IÂ learned how to navigate. Great skill, really.
The advent of GPS systems made it possible for sailors all over the world to find out where they are by simply pushing a button, and then a funny thing happened.
People began to forget how to navigate – or a least stopped learning. That is, navigate by mechanical instrument.
The same thing happened in photography.
The advent of automatic cameras (or even semi-automatic SLRs) meant that people just spun a few dials until a red dot came up. Today’s cameras have even obviated the dials to spin. All of this is a bit tragic because a fundamental connection between the physics of optics and a real measure of control over photography has been lost.
So here I am to re-instate it. Maybe.
Take a look at the photo above. It’s the downward looking view on an 80mm lens on a Hasselblad.
Note that there are four rows of numbers, from top to bottom:
1. The f-stop for the lens. That is, how wide or small is the aperture in the lens that lets light in. The smaller the f-stop number, the larger the opening, the more light
2. The distance from the object upon which you are focused, measured in feet.
3. The distance from the object upon which you are focused, measured in meters
4. The hyperfocal distance scale.
Ah, that last one is a bit of a mystery. But it is this last scale that will give you almost unbelievable control over your photo and video work.
The first thing you want to do is to focus on the thing that you want to take a picture or video of. Most people just spin the barrel of the lens until it comes into focus (or depend on auto focus), but the lens is really a device for measuring distance, and quite accurately.
Once you have focused on the object of your desire- a face, a building, whatever – take a look at the lens. It will tell you, quite accurately, in feet or in meters, just how far from you that object is. That is the feet/meters reading on the lens.
It is very important, as you will soon see, to know exactly how far from you each object is.
Now, look at the hyperfocal distance scale.
You see that the numbers are duplicated (except for the 2), on each side of the two are 2 fours. 2 eights, 2 elevens and so on. They match up.
Now, if you set the f-stop (first ring) at f-2, the only thing that is going to be in focus is whatever is directly above the ‘2’ on the hyperfocal distance scale. In this case, only something 3.1 meters away. Anyting in front of it, or behind it will be out of focus. But (!) by simply changing the aperture of the camera from f-2 to f-11, now, suddenly, everything from 1.3 meters away to infintiy is suddenly in focus. Change it to f-4 (without any focusing at all) and now everything from 2.1 to 5 meters away is in focus.
See what a powerful tool this is
You can now totally control where the focal plane starts and where it stops.
This technique is used in Hollywood all the time. In fact, they have people called focus pullers whose job is to measure, with a tape measure, exatly how far each object in the field of view is from the camera’s focal plane. Knowing this, a good cinematographer can totally control what is in and what is out of focus.
And now, so can you.
