Back to the Basics: How to Use a DSLR Camera

Focal Length: The distance from the optical center of a lens to the back of the camera, where the image is formed. It is a fancy way of saying how your camera and lens work together to show an image wide, normal, or telephoto. Your eye sees everything at fixed focal length of ~25mm.

Shutter Speed: The length of time that light exposes the film/sensor. This would be like you blinking, except with a camera, it “blinks” open vs. closed.

Aperture: The opening that allows light to pass through the lens. The dilating and contracting of your pupil is an excellent metaphor to the aperture on your camera lens.

ISO: Sensor’s sensitivity to light. Everyone has different sensitivity to light. On your camera, you can change that sensitivity level.

What is Focal Length?

You know that number in front of the “mm” on your lens? That’s the focal length in millimeters. I gave the fancy definition, but I have a nice comparison chart below (click the image to enlarge):

For all of these photos, I was standing in the exact same spot on my patio. I simply used a different lens and/or focal length for each photo. As you can see from the comparison photo, there is a big difference between each focal length. Each photo gives a different look and feel. Let me point out a few observations:

• At a lower focal length, you get more of the scene in the photo.
• As the focal length increases, the background of the subject gets closer to the subject.

My swingset is great and all, but what if you want to see this applied to people as subjects? (click image to enlarge)

You can really see in this example how each lens/focal length gives a completely different feel to each photo.

The type of camera you use can have a dramatic impact on your focal length. If you are using a full-frame camera, the focal length on the lens is the true focal length of what you are seeing through the viewfinder. If you are using a crop-sensor, there is a crop factor that you need to multiply your focal length by. I could go into more detail here, but an article from The Digital Photography School called Crop Factor Explained does a much better job than I would!

What is Shutter Speed?

When you press down the button on the camera, the speed in which it “clicks” is your shutter speed. If your shutter speed is 1/500, it takes 1/500th of a second for it to open and close. So, the faster it goes, the less light that gets in the sensor; the slower it goes, the more light that gets in the sensor.

There are two reasons why you would want a higher or lower shutter speed:

• Fast shutter speeds freeze motion of your subject; slow shutter speeds show the motion of your subject.
• Fast shutter speeds work better with full-light; slow shutter speeds are helpful when there is less light.

My got my son to help me demonstrate the effect a different shutter speed has on a photo. I had to tear him away from the computer, but he obliged. 🙂 (click image to enlarge)

A few observations:

• The rule of thumb for freezing action is a shutter speed of 1/250 or above. You can see from the photos that as soon as the shutter speed goes to 1/125, the scarf has some motion blur.
• If you have a faster shutter speed, you are going to need more light to properly expose the image. If you have a slower shutter speed, you need less light. Your shutter speed will be higher outdoors and slower indoors.

I should also discuss the two different types of blur in a photo:

• Motion blur: Blurriness caused by movement of your subject. Only the subject is blurry in an image.
• Camera blur: Blurriness caused by movement of the camera. The entire image is blurry.

Look at the image with the 1/30 shutter speed. There is only motion blur, not camera blur, since my son is still sharp and in focus. If the chair in the background was blurry as well, it would indicate camera blur. And yes, both can occur at the same time!

You can control both kinds of blur with your shutter speed. Motion blur is controlled by keeping your shutter speed over 1/250th of a second. Camera blur is controlled by keeping the bottom number on your shutter speed (1/250) higher than your focal length. For example, if you are using a 35mm lens, your shutter speed should be higher than 1/35th of a second. If you are using a 200mm lens, your focal length should be higher than 1/200th of a second. This is a key point to always keep in mind while you are taking photos. All of the rest of your settings (for instance, lighting, composition, and background) could all be in order, but all it takes is a shutter speed lower than your focal length to blur and ruin your entire image. To give myself a buffer, I try to keep my shutter speed at least a few notches above my focal length. If you have to have a shutter speed lower than your focal length, then try to steady yourself somehow, by leaning up against something or resting your arm/camera on a surface to help stabilize the camera movement.

The relationship between shutter speed and focal length can be ignored if you have a tripod. Since the camera is stationary on the tripod, there won’t be any camera blur from the movement of the camera! Flash can help with freezing motion as well, but we’ll save that for the lighting blog post.

What is Aperture?

Aperture is the size of the opening on the lens that allows light to pass through to the sensor. Aperture and shutter speed work directly together to properly expose an image. The chart below shows the different settings a camera can have, yet still yield the same exposure on an image. (click image to enlarge)

As the shutter speed goes up, aperture goes down and vice versa. Like I mentioned above, each of these settings will give the same exposure. So, what difference does it make which setting you use for your image:

• Amount of motion you want to freeze
• Focal length in relationship to your shutter speed
• Depth of Field: Distance between the nearest (subject) and farthest (background) that appear in sharp focus.

Sorry for more fancy talk, but photography is very technical, despite it also being an art. In short, depth of field (otherwise known as DOF) is the range of what is in focus in your image. If you have a shallow depth of field, a very small range of your image is in focus. If you have a deep depth of field, a greater range of the image is in focus.

Depth of Field is determined by 3 factors:

• Aperture size
• Distance of the subject from the lens
• Focal length of the lens

I will discuss these three points at length in a future blog post. For now, we are going to simply focus on aperture size. (click image to enlarge)

These photos were all shot from the same distance from the subject and with the same lens, which leaves the aperture setting the only significant difference. As the aperture goes up, you can see the tree more clearly. For portraiture, having a background blurry (better known as bokeh) helps to separate your subject from the background. With a lower aperture, you may get a greater effect on the image, however you risk not capturing the main part of your subject in your depth of field range.

Here are some tips to help you avoid this very common mistake that even seasoned photographers make:

• The higher your focal length, the more difficult it is to keep your subject within that depth of field range.
• The closer the subject is to the camera (no matter the focal length), the harder it is to keep your subject within that depth of field.
• If your subject is moving and you have a low aperture setting, it is very difficult to capture that subject within your depth of field. If you want to accurately capture your subject in focus, your aperture setting should be at least f/4.
• Sometimes this isn’t visible to the eye when you take a quick glance at the back of your camera (unless you zoom in). A subject may look like it’s within the range, but you will find out when you are processing the image that it is not. If you are attempting to get the blurriness effect of a lower aperture, take multiple frames to ensure you got what you want in sharp focus.
• If you are photographing more than one person in an image, your aperture setting should be higher than the number of people in your image.

What is ISO?

The final setting in creating your image. ISO is your sensor’s sensitivity level to light. Back in the film days, you had to buy film with a specific ISO speed and then make sure your camera was set to the same speed. Now with digital cameras, you can easily change this setting with a quick push of a button! (click image to enlarge)

The higher then ISO, the less light you need to properly expose your image. The smaller the ISO, the more light you need. You would want to use a lower ISO on a bright sunny day and a higher ISO at night or if you are indoors with little light. Why not have a high ISO setting on your camera all of the time? The only reason is the clarity of the photo and the amount of grain, but it’s a little difficult to see at first glance in the comparison chart above. If you look closely at the first image, you will see the first image is clearer. The last image has more grain and is slightly less sharp.

Where ISO really comes in handy is when you are attempting to set your shutter speed and aperture, but don’t have enough light to attain the settings you need to expose the image. That is when ISO comes to the rescue and enables the camera sensor to become more sensitive to the available light. Just make sure you know that the higher you go, the more grain you will get in your image. Unless I absolutely have to, I tend to try and stay below an ISO of 1250. However, I would be willing to sacrifice some grain to make sure I have an image with no camera or motion blur! Grain can be easily fixed in post-processing; blurriness cannot.

In Summary!

Whew! My quick and simple guide to how to use a DSLR camera didn’t end up being very short at all! There is certainly a lot of information to convey. Hopefully, new and established photographers have learned something new from this post. After being a photographer for all of these years, all of this information is automatic for me when I’m shooting. I can comfortably set my camera settings in manual mode, change settings on my camera while never taking my eye off the viewfinder, and be able to tell how fast my shutter speed is from the speed of the sound of the “click” of my shutter (my favorite). It definitely took a lot of time and experience, so try not to be overwhelmed. It will take patience and practice! Take your camera and do some of these experiments on your own. See what impact a higher aperture or lower aperture has on your photo. Try out shutter speed or the focal lengths of different lenses. The best way to learn is to go out and do it!

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Do you have any basic rules of thumbs you use while using your camera?

I’ve listed out my rules of thumb, but I’m sure there are more out there. I would love to hear what works well for you while shooting! What are some other ways you can put these principles to practice to fine-tune your photography skills?

Up next…

There is so much more than these settings goes into creating a final image, such as composition, lighting, and editing. I will be exploring these concepts in future blog posts, so stay tuned for those. For now, you can look forward to choosing the right equipment for your photography business!