F STOP NUMBERS FULL
F STOP NUMBERS ISO

Understanding f/stops aren’t hard once you get a bit of practice. Now you go in the opposite direction from f/5.6 to f/4 or from f/16 or f/11. The reverse would be opening up and doubling the amount of light. So you would stop down from f/4 to f/5.6, or from f/11 to f/16.

Stopping down just means you’re decreasing the amount of light passing through the aperture by half.

F STOP NUMBERS ISO

This relationship is explained more in a post I did about the photographic triangle which talks about the relationship between the aperture, shutter speed, and the ISO (sensor/film sensitivity). If more light can pass through your aperture, then you can use a faster shutter to get the same exposure. The more you can open the aperture, the more light can pass through. Lens speed refers to the maximum aperture a lens can open to. They require more glass elements, larger glass elements, larger barrels, and cost more to manufacture. The cost and weight of a lens goes up significantly as the aperture widens. This allows for lenses to be lighter and cheaper. When you are talking about zoom lenses, it’s common to see a range listed for the aperture. This means that when I am focused at 28mm I can open my aperture to f/3.5, but when I zoom in to 135mm the most I can open the aperture is to f/5.6. That means that if my focal length is anywhere between 70mm or 200mm, my aperture can open to f/2.8. On the first lens, the maximum aperture is f/2.8. The second numbers are the f/stop numbers. The first set of numbers are the focal length of the lens. And as you know by now, that is the lowest number it can open too. Lenses are categorized by their maximum aperture. From f/5.6 to f/2.8, you are doubling, then doubling again the amount of light passing through the aperture. When you move from f/11 to f/8 you are doubling the amount of light passing through the aperture. Soooo… When you move from f/4 to f/5.6 you are now letting in half the amount of light. The higher the number, the more you are dividing by which means your final number is less. Again, to keep it simple but to explain, these numbers are a ratio and are related to the diameter of the aperture (in mm). The higher the number, the smaller the opening and the less light will pass through. If I were to ask you which f/stop lets in more light, f/2.8 or f/11, which would you choose? Most people would probably say f/11 will let in more light than f/2.8 cause it is a higher number, but that would be wrong. This part isn’t as intuitive as it should be. “I want a stop more light,” or “I want two less stops.” They are just talking about the number of times they are halving/doubling the amount of light. NOTE: Sometimes when you hear the word “stop(s)” being used, they may just be talking about increasing/decreasing the amount of light but these ratios (in general).

F STOP NUMBERS FULL

F/7.1 lets 1/3 more light than the full stop of f/8. So f/6.3 is a 1/3 less light than the full stop of f/5.6.

Since the numbers above represent doubling/halving the amount of like, these numbers represent a 1/3 differences. These numbers fall in between the full stops listed above. When setting your aperture you may see other numbers like f/3.5, f/6.3, or f/7.1. When you change from one stop to the next, you are either halving or doubling the size of the aperture (in square mm) which also means you’re either halving or doubling the amount of light passing through to the sensor/film. So maybe you would shoot at f/2.8 or f/16. Lets start with a sequence of numbers you may be more familiar with. Wow, that sounds confusing! Technically it can be confusing, but don’t worry you don’t need to know the technical end to take good pictures.

They are ratios that half/double the hole of the aperture. This gives you the diameter of the aperture (which you don’t really need to know to understand f/stops) What are Stops? The f/stop is the focal length (f) of the lens divided (/) by the Stop of the aperture. This isn’t a post about apertures, although your f/stop relates to your aperture. Here’s a quick (or not so quick) post about f/stops.

F stop numbers