How to Use Your Camera's Aperture Priority

2024 Author: Samantha Chapman | [email protected]. Last modified: 2023-12-17 09:13

Aperture Priority or Aperture Priority is the preferred auto exposure mode of many photographers because of the control it gives, from those photographing vast landscapes to those photographing the smallest insect. It is considered by many to be the mode that comes closest to certain standards that photographers demand for their photos. Leaving the simple automatic mode and entering another mode forces you to think and allows you to control some important aspects of the image.

Note: This guide is for beginners; for more technical details go to How to Choose the Right Aperture (F Stop), which covers many aspects that are barely touched upon or ignored in this article.

Steps

Step 1. Set your camera to Aperture Priority

The wording is different for each manufacturer (read the manual), but here are some tips for the most important brands of digital cameras:

• Most Nikon DSLRs:

  You have a mode dial. Turn it to "A". Once you've done this, you can change the aperture by turning the front control dial (on the right handle, very close to the power button). If your camera doesn't have a front control dial, you can adjust the aperture with the rear dial.

  

• High-end Nikon DSLRs:

  Press the "MODE" button while turning the rear control dial until you see "A" on your top LCD. The front control dial will control the aperture.

  

• Almost all Canon SLRs (and some Canon compacts): Turn the mode dial to "Av". Aperture will be adjusted by the main control dial (next to the shutter button).

  

• Many digital compacts have Aperture Priority, but you have to look for it in the menu to activate and set it. This is a simple method of telling the computer and other parts to work together, which doesn't cost much more, but it's a sign that the manufacturer has made a point of getting you to get the best out of even a cheap camera.

Step 2. Memorize some basic terminology

You need it to understand the rest of the article.

• ’’’F / X’’’ indicates the aperture of the diaphragm. This number represents a fraction of the focal length of your lens in relation to its aperture. A smaller aperture is indicated by a higher f / number: f / 32 is a smaller aperture than f / 5.6, i.e. a smaller aperture, which means less light entering the lens.

  

• Close the diaphragm means using a smaller aperture (f / larger aperture).
• All open is the aperture set at its maximum aperture (minimum f-number).
• Shallow depth of field it is formally the area where objects appear in focus in the image. There is only one distance from the object where it seems perfectly in focus; the depth of field covers the area that is out of perfect focus but which still seems quite in focus, so that to the viewer anything in that area of focus appears deliberately in focus.

Step 3. Check your goals

All lenses are different and have an aperture at which they shoot better. Go out and take a few shots of something that has a dense texture at different apertures and compare the images to understand how the lens behaves at different apertures. Here are some tips on what to look for:

• Almost all lenses have low contrast and are less sharp at maximum aperture, especially in the corners of the image.

  This is especially true in 35mm and digital camera lenses. Regarding the engraving, it is a completely different thing from the depth of field; it is especially noticeable in the corners of the image. Therefore, if you want to have the background in focus you have to close the aperture. For normal subjects, usually f / 8 is the sharpest aperture.

• Most lenses vignette at maximum aperture.

  Vignetting occurs when the corners of the image are much darker than the center of the image. This can be a good thing for many photographers, especially portraits; directs attention to the center of the image, which is why many people add vignetting in post-production. But it's always best to know what you get. Vignetting is usually not seen beyond f / 8.

  

• All lenses become less sharp if you close the aperture enough.

  This is a physical limitation of the goals; letting light into a smaller hole forces the light rays to interfere with each other.

  

• Zoom lenses may vary based on how much they are zoomed in. Experiment as above at the different focal lengths.

Step 4. Exit and shoot

Step 5. Check the depth of field.

It's simple: a smaller aperture means more depth of field, a greater less. A larger aperture (smaller aperture) also means a more blurred background (which is similar, but not identical, to the depth of field). In short, the background can be blurred even if it distracts the attention. Here are some examples.

• Use a large aperture for more depth of field.

  

• Remember that the depth of field gets narrower the closer you get.

  If you do macro photography, for example, you may need to close down a lot more than for a landscape. Insect photographers often go to f / 16 or higher apertures, and need to illuminate subjects with lots of artificial light.

  

• 

  Larger apertures force the background to go out of focus; this is great for portraits. This image was taken at f / 2. Use a wider aperture for less depth of field.

  This is great for portraits (much better than a mundane automatic portrait mode), for example. Use the aperture as wide as you can, focus on the eyes, adjust the frame and you'll see that the background is out of focus and therefore less distracting.

  Remember that opening the aperture this way will force the shutter to close faster. In daylight, make sure the shutter is not at full speed (usually 1/4000 on DSLRs). Keep ISOs low to avoid this.

• Remember that you will not see any of this in the viewfinder (or on screen if you're composing). Modern cameras take "measurements" with the lens at maximum aperture, and only go to the right aperture at the moment of shooting. Plus, the viewfinders on modern DSLRs don't even show true depth of field if you shoot with fast lenses (i.e. with a higher maximum aperture).

  Many DSLRs have a depth-of-field preview button on the front of the camera. If you've ever pressed a button and wondered why the viewfinder went black, here's why. Unfortunately, since the viewfinder is obscured, it is very difficult to understand the depth of field in this way (although it can give clues as to how far out of focus objects are in the background, which is not the same thing). A better option on digital cameras is to simply take the photo, then review it by zooming in on the OCD to see if the background is in enough focus (or out of focus).

Step 6. Check the shutter speed

Using a wider aperture means you can use a faster shutter speed (or a lower ISO with the same speed); that is to say, a smaller aperture forces you to have a slower shutter speed, or to raise the ISO to take the same photo. This has some practical implications:

• Get the fastest shutter speed you can.

  For example, if you're shooting with the camera by hand or trying to capture motion in low light, set the aperture as wide as you can. Push yourself to the ISO limit too (the amount of tolerable noise is something you have to experience on your own). The camera will shoot at the fastest possible speed.

• Get the slowest shutter speed you can.

  This is great if for example you want to do a motion blur (think of those dreamy photos of flowing water). Set the ISO to minimum, close the aperture to f / 16 (or less, if you want to defy the laws of physics, or if you're okay with diffraction). The camera will give the slowest shutter speed possible (although modern cameras usually don't automatically expose for more than 30 seconds).

Step 7. Look for the best image engraving

As already mentioned, almost all lenses are more sharp if you close the aperture a little. If you've done the tests as suggested, use this aperture for all shots where you think you'll have adequate depth of field and shutter speed. For those of you who photograph using a tripod, use this aperture all the time.

If you're too lazy to take your own tests (and really testing subjects like walls is boring), then folk wisdom comes in handy: f / 8 is fine. f / 8 usually gives sufficient depth of field for most still subjects and usually the image is sharp at most (or nearly so) in most DSLRs and 35mm film

Advice

• When you're not actively using the camera, keep it ready for whatever comes your way by leaving it in automatic mode, or perhaps aperture priority with a reasonable fixed aperture like f / 8.

• Don't worry about the test results.

  The tests tell you how to get the best results on any subject in an ideal tripod situation, not in the shots that allow real-world conditions. Particularly:

  • If you really need a lot of depth of field, don't worry about using smaller apertures, even if the diffraction is evident.

    Blurring caused by part of the subject out of depth of field is a very complex thing and impossible to correct; it is an extraordinarily complex phenomenon that changes from lens to lens, and sometimes even on the same lens based on aperture, subject distance and focal length.

    Diffraction, on the other hand, is a relatively simple phenomenon. A simple unsharp mask on your image post production program usually works just fine.

    

  • Don't hesitate to shoot with the aperture wide open if necessary.

    For example, if you are shooting with the camera by hand and can't avoid shaking a little, or if you want to catch the movement, then shoot wide open; a slight blur in the corners is much less horrible than a blurred image or the trail of a moving subject. Lower contrast is easy to correct on a computer.

    

• Stopping down to f / 16 or less, with many lenses, turns bright spots into "stars". These usually have the same number of beams as your lens' aperture blades (if they are even) or double (if they are odd).

  

Warnings

• Using a small aperture (high f-number) can also bring unwanted things into focus, such as dust on the sensor or dirt or damage to the lens. You may need to clean the sensor or lens, or edit images on your computer. If the lens has a large scratch, avoid pointing straight into the sun, which could cause a flare.

  • Cleaning too thoroughly can cause further problems over time than a little dust. If you have a cheap filter on your lens, preferably coated or multi-coated to avoid flare, clean it as much as you like.
  • Dust on the sensor shouldn't be a big deal if you switch lenses to a calm, relatively dust-free place.