Greetings, volks. Welcome to Hohenfels Volks, THE place for our place! Brrr. That’s our word of the day!
Today we’re going to review some of the basics of photography and exposure. This can all be found on our Introduction to Photography page. We should all have a good idea of this stuff, but it always helps to refresh the cup, so to speak.
First, we’ll address our exposure triangle. The triangle consists of 1- ISO or film speed, 2- shutter speed, and 3- aperture. To change exposure, you change any side of the triangle. To keep the same exposure, you have to change at least 2 sides. For instance, we set up on a sunny day at ISO 100, f/16, and 1/100. According to the “sunny 16 rule,” we’re good to go. But we want less DOF, so we need to increase our aperture. We go to f/4 to give us a shallow focus. If we don’t change another side of our triangle, we overexpose and create a mess. We have a 4-stop increase in the amount of light coming in, so we need a four-stop increase in shutter speed or 4-stop decrease in ISO. Since we can’t bring our ISO lower, we need to change our shutter speed to 1/1600. At 1/1600 at f/4, that gives us the same as 1/100 at f/16. If we want to increase our exposure, we can change any 1 side and either decrease our exposure or increase it depending on our new settings. For instance we want to increase our exposure on ISO 100, f/16, 1/100 2 stops, so increasing our aperture to f/8, decreasing our shutter speed to 1/25, or increasing our ISO to 400 will do just that. Remember, when we meter something, or a scene, the meter gives us the exposure for 18% gray, which is zone 5. Knowing this allows us to place the item we meter into different zones or exposure levels.
Next up, we’ll look quickly at depth of field, or DOF. This is a product of our focal length and aperture. The longer our lens’s focal length is, the shallower our DOF. The wider our aperture is, the shallower our DOF. This can be a good way to remove or minimize distractions. A 100mm lens at f/16 has about the same DOF as a 50mm lens at f/4. Focused at 10 feet, both give a DOF running from about 9.17 to 11 feet. Seeing that, you can deduce that a shorter lens has a wider DOF.
Remember, these 2 topics we’ve reviewed go together. By adjusting your aperture for a shallower DOF, you’ll have to change something else to maintain your exposure. If you wish to move into a new zone, you’ll change your DOF if you use your aperture to move zones.
We’ll review composition and inspiration in our next talk. Remember to vote and get your pics in early. I hope you’ll all participate in this week’s theme, solitude. We’re aiming for more votes for our theme, so get involved and let’s enjoy the journey together!
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