The Holy Trinity: ISO, Aperture, and Shutter Speed

Any introduction to photography must begin with the discussion of ISO, aperture, and shutter speed. They’re the three most important settings over which a photographer has the most control. They’re also the most responsible for whether you get a usable image or not.

First off, let’s define usable.

Why are you taking the photo? To document an event? For publication? For digital use only or for print? Just because it seems to be the thing to do today? Each usage has a different criteria and photographic standard.

Selfies and shots at the club are lowest on the list for quality imagery. This site won’t really be relevant for those who just post blurry photos of sunsets on Facebook. Instead, we’ll be looking at producing higher quality photos for definite end uses.

For that you’ll need to know the settings on your camera and how they interact.

Anthony Jeselnik at the Royal Oak Music Theatre, Royal Oak, MI, 24 October 2013. Nikon D5100 1/200, f5.0, ISO 5000, 50mm.

Comedian Anthony Jeselnik at the Royal Oak Music Theatre, Royal Oak, MI, 24 October 2013. Nikon D5100 1/200, f5.0, ISO 5000, 50mm.


ISO, the camera setting, was created by ISO, the International Organization for Standardization, as a replacement for ASA, or American Standards Association. ISO is a scale for the light sensitivity of your camera’s sensor. With a few exceptions, the base ISO of a camera is 100. Above that, there is an increasing amount of “noise” added to the image. More on that later.

The lower the ISO the less sensitivity of the sensor to the available light. An ISO of 200 is twice as sensitive than ISO 100, and so on.

Typically, in low-light situations, you will want to increase the ISO setting to compensate. However, the higher up the scale, the more noise, or grain, introduced to the photo. Today’s cameras handle high ISO very well, before the grain becomes noticeable; sometimes in the tens of thousands on higher end cameras.

In a general sense, the goal is to shoot at the lowest ISO possible, to reduce the amount of noise, while still producing a properly focused and lit image. This is made possible by adjusting ISO in conjunction with aperture and shutter speed.

The shot of Anthony Jeselnik at the Royal Oak Music Theatre employed an ISO of 5000 because of the low light, even though he was lit by the spotlights. I was able to keep the ISO somewhat low as well as a medium aperture because the shutter speed allowed more light to hit the sensor. The combination helped to reduce the amount of grain in the image.

The Silver Ambassadors perform at a Wounded Warriors function on 26 July 2014. Nikon D5100 1/400, f9, 400 ISO, 270mm.

The Silver Ambassadors perform at a Wounded Warriors function on 26 July 2014. Nikon D5100 1/400, f9, ISO 400, 270mm.


The aperture setting indicates how wide the camera’s diaphragm opens to allow the entry of light. The aperture is the opening in the diaphragm.

Measured in f-stops, the lower the number, eg: f2.8, the larger the opening, and therefore the more light which hits the sensor. The margin of f-stops you have available is dependent upon the quality of lens you are using.

Higher end, and thus more expensive, lenses can offer the lowest f-stops available. As an extreme, the Zeiss f0.7 50mm and 35mm lenses were made in the 1960s. Apparently you can rent one for around $5,000 a day, but the actually price has not been reported.

The commercially available Nikon AF-S 50mm f1.4G is $560 while the Nikon AF-S 50mm 1.8G is less than half the price at $250.

The lower f-stop you have available, the better the lens in low light situations, therefore the lower the ISO you can use, producing the least amount of grain in the photo. Generally speaking.

The f-stop will also determine the type of background and foreground rendering of your images. Again, the smaller you shoot (the higher the f-stop) the more “out of focus” the background. This will allow the subject to pop from your image and draw the eye to the most important part of the shot.

The trade-off in wider apertures (lower f-stops) is the reduction of depth of field. More on that in another installment.

The trees behind the Silver Ambassadors are a collection of green instead of them competing for the viewer’s eye, which is instead drawn to the clarinet player. Even the trombonist one row back is slightly reduced in focus largely because of the f9 aperture setting.

James Hinchcliffe enteres Turn 1 during IndyCar qualifying at the 2016 Chevrolet Detroit Belle Isle Grand Prix in Detroit, MI, on 3 June 2016. Nikon D5500 f7.1, 1/800, 100 ISO, 330mm.

James Hinchcliffe enters Turn 1 during IndyCar qualifying at the 2016 Chevrolet Detroit Belle Isle Grand Prix in Detroit, MI, on 3 June 2016. Nikon D5500 f7.1, 1/800, 100 ISO, 330mm.


Lastly, there is the speed at which the shutter opens and closes. The faster the shutter, let’s say 1/2000 of a second, the less light is allowed to reach the sensor. Less light will result in a dark photo. To offset that, we need to increase f-stop and/or increase ISO.

The lower the shutter speed, less than 1/50 of a second, you begin to introduce camera shake into the image, throwing off the focus. Everyone is different and that shake will become evident at varying shutter speeds. Some people can handhold a camera with little shake at 1/2 second while others cannot be relatively stable at less than 1/500.

The shutter setting depends on what you are shooting and what you want in your image. If you’re shooting fast-moving sports, you want to freeze the action and capture as little image blur as possible. However, in motor sports, you generally want to see some movement in the tires, for example, so you’re not just looking at what could be a car parked on the track.

Photographing children at play carries the same concept. While some blur may add an artistic element to the shot, too much can make the image unusable. You want to see movement in the rotor of a helicopter, but the rest of the vehicle should be in focus.

The interaction of the three elements is a trade-off which is dependent upon what you are shooting and what the final image needs to look like when viewed at the time you are shooting and considering the available light. Always continually assess the situation and circumstances for changes to the input and how you need to react to, or anticipate, the conditions.

As Oakville’s James Hinchcliffe enters Turn 1 during IndyCar qualifying in Detroit, the blur on the tires provide a sense of the car in motion


Are you shooting sports, landscapes, wildlife, or stationary objects? Are you indoors or outside? Cloudy or sunny day? What is the lighting like in the auditorium?

A couple of things we haven’t discussed is the use of a tripod and a flash unit.

A lot of times when photographing events, you are prevented from using a tripod. You may be able to use a monopod, but organizers will tell you up front that tripods are a no go. However, if you’re shooting landscapes, a tripod will be indispensable. The use, though, will affect what settings you use for the Trinity.

The same goes for flash units. When shooting concerts and sports in particular, you cannot use a flash, for obvious reasons. But you can, if need be, if photographing a speaker at a rally or in low light at a birthday party. Flash will freeze the action and illuminate the scene. But, it will also freeze that helicopter rotor. Using flash at a press conference is fine, but not at the ballet.

I tend to not use flash, but have it ready in case I need it. I also don’t generally use a tripod (though I do own one), but I do use a monopod when using a large lens which I can’t handhold to any beneficial degree. Smaller lenses are more mobile and easier to swing into action when needed, but sometimes you just have to carry the big glass, so you should be properly able to use it.

We’ve just scratched the surface when it comes to ISO, Aperture, and Shutter Speed and their interaction. This wasn’t meant to be a delving into the science behind any of them, nor will I approach that in the future. We will expand on each of them in future posts, but this was meant as an introduction to how they combine to produce a photo. They will be coming up a lot as we progress. We can’t really avoid them.

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