This monthly feature is my space to practice photography one step at a time. From this month on, I invite you to participate in this endeavor. Read on to know more about aperture priority and depth of field, to see how I get along using them and to learn how you can take part in the fun.
Usually, the goal is always going to create a picture with maximal detail in both the dark and the bright areas of the picture. The camera’s automatic mode achieves this in most situations. However, the settings which lead to this exposure are not unique. Correct exposure is the result of a combination of three things: how long the shutter is open (exposure time), how wide the shutter is opened (aperture) and how sensitive the sensor or film is (ISO value). It is perfectly possible to manually set one of these values and to adjust the others accordingly. Choosing a combination of aperture, exposure time and ISO setting is a creative decision. Large apertures (small f-number) can be used to create images with a blurred background (small depth of field). A short exposure time can be used to freeze motions. A high ISO value allows to take pictures in dark settings without flash.
Today, I will focus on depth of field, an important tool in image composition. Landscape images like the one above, and establishing shots usually want a large depth of field. We invite the viewer to take in the whole vastness of everything in these images, so we have to make sure that everything from front to back is rendered sharp. In the image of the prayer flags, we cannot only see the flags themselves but we also see the mountains behind them and the clouds in the sky, even though they are all at very different distances from the camera. Small apertures like f10 or f11 are typical for landscape images. Note that fast motions may become blurred since small apertures require longer exposure times and that shaking may be an issue in hand-held landscape photography.
Larger apertures can be used to emphasize a particular part of the image. In the image above, I used the largest aperture possible to blur the background and turn the viewer’s attention to the incense spiral on the front-right. More example images with a small depth of field are included in the previous post of this series.
The easiest way to adjust the aperture is to use the aperture priority mode of the camera, usually marked by an “A” on the mode dial. In this mode, you can set the aperture and the exposure time (and ISO setting if you do not fix it) is calculated automatically. The LCD screen does not show the same depth of field that you will have in the image unless you are using very large apertures. If your camera has a live preview, you can use that as a help to compose images with small aperture and long exposure times in situations where a quick reaction is not crucial. Since you will more often than not want to catch a fleeting moment, it is best to practice choosing the right aperture without using the preview.
I created the pictures below specifically for this article. I mounted my camera on a tripod, adjusted the white balance, and shot in aperture priority mode at a fixed ISO setting. The exposure time was calculated automatically by the camera. I noted the settings for each image in its top right corner, using the format aperture, exposure time in seconds, ISO value. See how the exposure time gets longer and longer as I move to smaller apertures (larger f-numbers)?
The focus was fixed on the first lighted candle in all images. Pay attention to the Advent wreath, the little angel in front of the wreath and the paper angels on the ground to see the changes in the first three images. Focus on the napkins on the ground and the plant right behind the Advent wreath to see how an even larger section of the image becomes sharp with smaller apertures in the fourth and the fifth image. To see the difference between the two images in the last row, look at the background of the image.
If you are eager to improve your photography skills too, make a post with an image that you shot in aperture priority mode and link to this article. While I am not an expert in iphoneography, there do seem to be apps to add manual configuration modes to your iPhone camera and I hope that some of you will contribute entries shot in this way. If (and only if!) you do not use WordPress, add a link to your post in the comments section. Write about whatever you want but do include a short description of how you took the image and why you chose the settings you used. Unrelated links and pingbacks will be removed. Travel and/or photography related posts are particularly welcome but everyone can participate. I will collect all entries made until Dec. 31. Provided that there are enough entries, I will publish a roundup of the entries before the next edition of “Tech of the month” goes live in January.
And of course, you are also invited to ..
This article was published on perelincolors.com