There will be times, when you simply cannot slow your shutter speed enough; you have opened the aperture of the lens as wide as it can go, and you just don’t have enough light to get a good enough exposure.

When such a situation arises, it is time to adjust your ISO

The topic of ISO was very briefly touched upon in the Water In A Bucket article, and as stated the ISO was essentially the size of the bucket.

A smaller bucket is easier to fill, and therefore gives greater flexibility when setting your shutter speed and aperture in a greater number of lighting situations.

The depth of field issues you may encounter as you adjust the aperture; the motion blur you may capture as you adjust your shutter speed; ISO too has a possible outcome in your final image: Grain.

Adjusting the ISO too sensitive (The higher the number i.e. ISO 6400) will create unwanted specks, dots, and discolourations.

The higher the ISO, the more grain there will be.

It’s always a good rule of thumb to try to adjust your light source, aperture and shutter speed to gain proper exposure then adjust the ISO if the first three can no longer be pushed or it degrades the quality of the image to unacceptable levels.

If you’re curious about seeing the grain ISO creates. Take a photo of the same subject. One with a high ISO (more sensitive to light aka small bucket), and one with a low ISO (less sensitive to light aka bigger bucket).

Zoom into the image. Right up to the pixels and you should see a difference between the high and low ISO images.


One of the major contributors in how your photo is exposed lies on your lenses aperture setting. This is something that was briefly discussed in my Water In A Bucket Theory.

You may recognize this setting as it is characterized by a number you may have seen as you have experimented with your camera i.e. 2.8, 5.6, 14 etc

Essentially what it is is the size of the opening in your lens which light is allowed to pass through (and fall on your CCD or frame of film)

The wider the hole, the more light can pass through, and vice versa, the smaller the hole the less light can pass through.

Again, if you refer to the Water In a Bucket article, Aperture would represent the girth of the hose. If you also read the article you will know why this is important.

One thing that hasn’t been discussed is the possible effects that you have to consider when adjusting the lens aperture, particularly your DEPTH OF FIELD.

Think of your depth of field as a “zone”. It’s an imaginary zone that exists in front of your camera.

The zone has one main dimension: length

Anything that falls in this zone will be in focus.

Anything that falls outside of it, be it too close or too far, will be blurry (to varying degrees)

We refer to how long this zone is, as how DEEP it is.

Also we refer to the zone as a FIELD

How DEEP is the FIELD? Is a question the photographer asks themselves.

What is my Depth of Field?…


Here are some examples:

The depth of field (abbreviated as DOF) is very long. So long in fact EVERYTHING is in focus

The DOF is short. Just a few feet. Just enough for a child to fit in so they appear focused where everything else is blurred.

The DOF is very short. Actually just a sliver. It doesn’t even consume the entire subject.

There are apps that you can download (Search: Depth of field calculator) or if you really wanted you can calculate it yourself.

But if you’re like me you don’t have the time to figure out an exact number so I just follow the laws that govern depth of field

1) The wider your aperture. The lower the number – Light will pass through faster and vice versa. (Smaller aperture. Higher number. Light struggles to pass through)

2) The wider your aperture, the smaller your depth of field will be and vice versa.

3) The closer you are the smaller your depth of field will be and vice versa.

Because I mainly shoot guerilla style, I calculating as exact and ideal depth of field is very cumbersome. After a while as experience  builds you can figure out what setting typically works best for your particular conditions (light, positioning, etc)

You can also opt to use your cameras APERTURE PRIORITY setting and simply set your aperture, and let the camera figure out all the other settings.

It’s all about experimentation, as it will lead to experience and knowledge.

Have fun shooting!!

Shutter Speed

The passage that rays of light take going through the camera lens and onto the sensor (or film) must first pass the shutter – which for the most part remains closed.

But it does open up! Usually for just fractions of a second – even for a thousandth of a second! Other times longer.

A lot of how you set your shutter speed would be based on achieving a proper exposure (Read the Water In A Bucket article. In this case Shutter Speed is represented by the faucet)

There is however one main consideration when you change your shutter speed, and that is motion blur; those fuzzy streaks that can ruin a photo just as easily as it can enhance it.

Want to make something appear to be moving?

Suggesting motion in still images can be impactful at times, however too much motion blur, or any motion blur at all can be the clear cut deal breaker between a good photo and a bad one.

If you experience motion blur when you do not want any, it’s usually an indicator that your shutter speed is too slow, and that you need to make it faster, and balance your exposure out by adjusting your other settings.

The opposite holds true, if you feel, as the creator of the image, that adding motion blur would in fact add value to the final result, then perhaps you should consider slowing the shutter speed down until a the desired effect is achieved.

Experience is a great teacher. The more you shoot, the more opportunities you will have to exercise what you know and, in turn, the better you will be.

Photography exposure – Using the water in a bucket theory

Clear your mind and imagine this. It’s a challenge. To start things out, imagine you have a water faucet. There is a hose attached to the faucet. At the other end of the hose, there is a bucket.

When you open the faucet, water flows through the hose and into the bucket.

Once the bucket is filled to the top, you successfully complete the challenge.

You fail if the bucket that overflows or if the bucket isn’t filled up.

Simple. Right? And it definitely would be, but imagine that you had to do this with your eyes closed.

You couldn’t visually see the bucket filling, and instead you had to give instructions to a machine that would do it for you.


Now you may ask yourself:

How long should I keep the faucet open for enough water to flow through and fill up the bucket?

How fast is the water flowing? Water that flows faster is sure to fill the bucket faster.

How big is the hose? A bigger hose would be able to deliver more water.

How big is the bucket? A smaller bucket will be full sooner than a bigger one.

All of these are valid questions, and with a few tries you might actually fill the bucket to the brim!

But believe it or not, this concept of filling a bucket with water is, in one way, how you should think about photography as you balance your shutter speed, aperture, and ISO so that you get a photo is isn’t too dark and isn’t too bright/washed out.

In photography, we don’t deal with streams of water. We deal with rays of light.

This, in photographic terms is called: EXPOSURE.

How will you EXPOSE the film or the sensor in your digital camera to light?

How long? How much? How big is the “bucket” that you need to fill?

In the water/faucet analogy, think of this when you compare to your camera

How long you open the faucet for = Shutter speed

How wide the hose is = Aperture

How big the bucket is = ISO

How strong the water pressure is flowing out of the faucet = The strength of your light source

Sometimes you will have the power to control all of these factors. You will be able to choose whatever shutter speed you want, the aperture, the ISO and your light source.

This is typically a studio situation.

Other times, you will only be able to control a few of these, for example if you are shooting outside. The sun (or stars) will provide light for you, and you have to adjust the other three to compensate so that you “fill the bucket” .

You may keep the shutter open for a split second when the sun is bright, or you may keep it open for a while as the trace amounts of light can trickle into the camera when shooting at night.

An important thing to note is that adjusting your shutter speed, apeture, and ISO has an effect on how the final image looks, and I dive further into it in their own dedicated tutorials.

Just remember, the water in a bucket analogy is just one part of photography, that I feel is something every person learning this craft should know and apply.