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Photography Tutorial: A Quick Start Guide to Understanding Aperture, Shutter Speed and ISO

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I first learned the basics of photography on a Nikon that I used to borrow excessively from my then boyfriend, now husband. Like most beginners, I stayed firmly in the auto setting at the beginning. It was often frustrating because my photos rarely turned out how I wanted them to so I would take about a 100 photos to get 1 that was close to what I actually wanted. 

At some point, I realized that if I learned the technical aspects of photography I would be able to get closer to my ideal image without my early spray and pray shenanigans. Without any real photography guidance, I decided that reading the manual would be the best place to start. I was 18 or 19 or something like that so my problem solving skills were honed for calculus not life.  Reading the manual was helpful for learning how to get to just about every function on the camera but it didn’t help be understand the basics of photography. 

Here are all the things about aperture, shutter speed and ISO that I wish someone explained to 19 year old me. 

The basics: a quick guide to photography


The aperture controls how much light is let in through the lens and it impacts the depth of field. Photos where the background is all soft and slightly out of focus (which is called bokeh) generally have a low aperture(f/5.6 and below). 

Most of my initial confusion about aperture happened because of how photographers occasionally talk about it. Since aperture refers to how much light is let into the lens, photographers will occasionally say that they’re shooting wide open, meaning that they’re at a low aperture or f-stop (below f/5.6). I find it simplest to talk about aperture in terms of f-stops since that’s more exact and makes it easy not to get mixed up. Talking about aperture as “wide open” or “really high” is a recipe for confusion.  Young me often nodded along in these moments totally confused but a tad worried about looking like I didn't know what I was doing, which in retrospect was a silly concern since I actually didn't know what I was doing! 

My other point of confusion occurred with understanding how to consistently create bokeh in images. To create bokeh, you need to shoot at a low f-stop. While I quickly got the hang of that bit, I was occasionally befuddled as to why I was unable to create bokeh even though I was shooting at a low f-stop. It took me a while to understand that the distance between me, the subject and the background was also important. The closer you get to whatever you’re photographing, the more blur you can create even at a relatively high f-stop (f/5.6). Also, the background needs to be relatively far from the subject to blur out. If the background is relatively close to the subject and you’re further away, it’ll be difficult to create bokeh (though sometimes this can be advantageous in low-light situations where you need everything sharp).

For example, both the photos below were shot at f/1.4. In the image below, the horse is close to me and everything in the background is at least a few feet away.

Bokeh example

For the image below, I hadn't reset my settings so I was still shooting at f/1.4 but the horses had meandered away. The distance between me and them was too far for any bokeh to occur even though I was still at f/1.4.

Aperature and Bokeh explanation

Lastly, your lens will impact the look and quality of the bokeh in your images. Many portrait photographers will use a 80mm prime lens for the quality of the bokeh. 

Shutter Speed

This is the speed that the shutter closes to capture your image. While I found myself pretty confused by aperture in my early days , shutter speed somehow always made intuitive sense to me. Slower shutter speeds help you capture a longer period of time so if things are moving, they'll blur. The image below was shot with a 1.6 sec exposure. These days, I rarely go for long exposure photos because I don't like lugging around a tripod. In the photo below, I used some random cement block to steady the camera. 

Long Exposure Example

Those magical waterfall photos that populate the internet are all done by lowering shutter speed. The image below was shot at 1/4 sec. and with an ND filter because it was in the middle of the day. 

Long Exposure Example with an ND filter

On the flip side, faster shutters can freeze moments in time so they're useful in fast moving situations. Sports and fast moving pets are frequent examples. I personally use faster shutter speeds to capture wildlife, partially to freeze motion but partially to capture more frames in a moment where I'm not sure what will happen. 

Shutter speed sample image

One final note on shutter speed, a rough rule of thumb to avoid shaky images is to never shoot below your focal length multiplied by 2. So if you’re shooting on a 50mm prime lenses, your shutter speed shouldn’t dip below 1/100th. This isn't a hard and fast rule, just a nice starting point when you're working towards getting your settings right. This shutter speed explainer has some nice breakdowns of how fast you'll need to set your shutter speed to freeze various movements. 


ISO controls how sensitive your camera sensor is towards light. With film, you’d pick your ISO via your roll of film so it translates in a somewhat funny way from film to digital. For film, you'd be at the same ISO for your entire roll of film. With film photography, you adjust aperture and shutter speed while ISO stays constant. For digital photography, you can adjust aperture, shutter speed and ISO. In some ways, I feel that fewer variables are incredibly nice but having the ability to adjust ISO with each image gives you greater control. 

When I switched from Nikon to Canon one of the biggest changes for me was having quicker access to ISO. On Nikon DSLRs, the ISO setting is in the menu so I would always have to pause shooting to adjust. On my Canon 5d mark iii,  I can adjust the shutter speed, aperture and ISO all with my right hand, without having to pause. 

When I was starting out, everything I read seemed to take the stance that you should work towards keep ISO as low as possible. Usually these sorts of articles would come with sample images of the same moment at different ISO levels and then each sample image would have some slice of it blown up 10x so you could see the grain. I would also sort of squint and try to see the variations. Over the years, I've realized that I've never taken a photo I was admiring and blown it up 10x to examine the grain. 

Putting it all together

Even once I started to understand aperture, shutter speed and ISO, I still found it difficult to piece it all together. Personally, I most often decide what aperture I want to shoot at and from there adjust my shutter speed and if necessary my ISO. These days, I mostly shoot with my camera set to manual and I adjust as I go. If I'm photographing people in variable light conditions, I occasionally jump into aperture priority mode. 

Understanding the basic components of photography was immensely helpful but the most important aspect of photography, in my experience, is practice. Once you have the basics down and know how to adjust your camera settings, go out and just shoot.