How to Use Your DSLR Camera: Selecting the Best Aperture, Shutter Speed, and ISO


In the first of these four articles about using your DSLR in modes other than P, it was discussed how your camera makes assumptions about the amount of light when it is in P or Program mode and how different shutter speeds and apertures can affect how much light reaches your DSLR’s sensor. This article covers how to select the best shutter speed and aperture. Additionally, it introduces ISO, which enables you to adjust the sensor’s sensitivity on your DSLR.

Imagine you wish to take pictures of two very different scenes: your son standing confidently in the mountains with a beautiful backdrop and your daughter dancing at a party with a distracting background of chairs and tables.

The mountains in the backdrop of the photo of your son are sharp. However, they are blurry in the shot of your daughter.

What does your camera in P Mode assume about the background’s significance to choose whether to blur it? In most cases, your camera has no notion what’s in the environment. A camera will attempt to match your scene with its memory to impose the perfect shutter speed and aperture. Depending on the model, a camera may have thousands of photographs of locations and the optimal shutter speed and aperture for each scenario, recorded in its memory. This “memory” method will never match your knowledge of the scene. How do you tell your camera whether or not you want the background once you’ve decided?

By adjusting your camera’s aperture, you may decide how much of the backdrop will be in focus. The background will be blurrier the more significant the gap (f5.6 instead of f11). The aperture on the image of your son is f16, whereas the crack on the idea of your daughter is f4.

When all you need are f4 and f16, why does your camera provide so many aperture options? The answer is complicated since variable lens lengths and your distance from the subject will change the plane of focus, essentially how much of your issue is in the direction in front of and behind it. Use the most excellent aperture to blur the backdrop for this post, which is meant for anyone looking to advance beyond the P mode, and either f11 or f116 to maintain background details.

But how do you adjust the camera’s aperture? The solution is to switch your DSLR’s command dial from P to A, which stands for aperture priority. Once you’ve done this, you have to dial in the desired aperture, and the camera will choose the proper shutter speed on its own. This would be so simple if we didn’t have to worry about shutter speed. Only a minimal quantity of light can reach your camera’s sensor when you use a very narrow aperture. Therefore you have to leave the shutter open longer than you would if you had chosen a considerable gap. The boy in the two images above is still, so the 1/180-second shutter speed is not an issue. However, the girl is dancing, so if I had used a 1/180-second shutter speed, she would have been blurry. Instead, I chose a 1/150-second shutter speed. Which shutter speeds will produce the best results, then?

While capturing a landscape, your shutter speed should be 1/60th of a second or faster (for example, 1/250th of a second). When photographing a still subject in a landscape, your shutter speed should be at least 1/180th of a second or faster. If you snap a dancing female in a landscape, your shutter speed should be 1/500th of a second or faster. If you want to capture a running female artistically and want her to be blurred, ensure the shutter speed is around 1/15th of a second, as in the image below.

Imagine you want to capture your daughter dancing in the mountains on camera. Your camera’s readout indicates the shutter speed has been set to 1/125th of a second, which is 1/3 too slow (1/500th of a second is twice as fast as 1/250th of a second, which is twice as fast as 1/125th of a second), so what should you do? In aperture mode, you choose a tiny aperture, say f11, to ensure the mountains behind her aren’t a blur but a disaster. Your gap might be raised to f5.6. (remember from the first article that f11 lets in half the amount of light that f8 does, which in turn allows in half the amount of light that f5.6 does).

However, an f5.6 aperture will obscure the mountains, so what should I do? When you come home, tell your daughter to stop moving so you can make her dance in Photoshop. Instead, it would be best to increase your camera’s light sensitivity so that at f11, your shutter speed will be what you want—1/500th of a second. If you increase your camera’s light sensitivity by three times, this will work.

But how can you increase the sensitivity of the camera’s sensor? In the dark age before digital DSLRs, your camera would be loaded with a quicker film. An 800 ISO (also known as ASA) film is twice as sensitive to light as a 400 ISO film, which is twice as sharp as a 200 ISO film. Movies are rated according to their sensitivity to light. In other words, a 200 ISO film needed three times as much light to record the same amount of light information on the movie as an 800 ISO film.

Why, then, does this matter in the digital age? because you can easily alter the sensor’s sensitivity in your DSLR “mid-roll.” Suppose your camera’s ISO was 200 when you discovered it chose 1/125 of a second when you decided on f11, and you wanted to capture your daughter dancing on a hillside. In that case, all you have to do is raise the ISO to 800; your daughter and the mountains behind her will be beautifully sharp.

So why don’t cameras always utilize an extremely high ISO? The amount of “noise” increases with the camera’s ISO speed. This is undesirable from an aesthetic standpoint because it causes tiny dots to appear where there shouldn’t be any in the picture’s shadow or darker sections. Additionally, there are occasions when you wish to combine a slow shutter speed with a narrow aperture.

In conclusion, a larger aperture will blur the background and require less light for a given ISO than a smaller aperture, which would keep background detail but demand more light. Your DSLR’s sensor will become more light-sensitive when the ISO is increased, enabling you to utilize a suitable shutter speed for the chosen aperture.

The following article will cover how your camera focuses in P mode, along with information on ensuring that your subject is sharply in focus.

Regarding John Slaytor

I have a hard time focusing on my photographic interest. I can write a lot about this lack of attention to detail. My portfolio of work includes pictures of Indian and Greek families, Chinese and Ghanaian football fans, Auschwitz-Birkenau concentration camps, Nigerian 21st birthday celebrations, Macedonian weddings and christenings, Nigerian 21st birthday parties, Presbyterian and Catholic funerals, and Sydney Opera House.

I can and do travel anywhere for work, even though I live and work in Sydney. I want to think that Werner Bischof, with his subdued humanistic outlook; Jane Bown, with her technological minimalism, Eve Arnold, with her compassion; and Peter Dombrovskis, with his pure pictures, have all had a beneficial influence on me. I discovered Michael Kenna after visiting Auschwitz; his art has helped me grasp how buildings can have moods.

(I steer clear of formality and artificial lighting because they call too much attention to photographing someone. I have no problem using a tripod to take pictures of structures for extended periods.)

I shoot with Nikon cameras and only use DXO to edit RAW photos. I use an Epson 4800 to print. My screen is an Eizo, and my computer is a Mac.

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