To help us all brush up on our skills, I'd like to propose a challenge! One of the best ways to improve your skills is to learn how to use your camera in anything other than its automatic mode or any of the auto subsets.
Let's take a look at the image above, which was taken of a Canon Rebel. The green box indicates that you are letting the camera choose everything for you. All of the modes below this setting are simply subsets of auto, for example "portrait" or "action." All these subsets do is tell the camera that it can still choose everything for you, but it will lean towards a certain shutter speed or aperture setting. Even P (Program mode) and A-DEP (Auto Depth of Field) gives exposure control to the camera.
As a serious photographer, out of all of these settings, there are only three modes that we should care about. They are Shutter Priority (Tv on Canon, S on Nikon), Aperture Priority (Av on Canon, A on Nikon), and Manual (M).
CHALLENGE! Everyone reading this should take their camera out, put it in Manual mode, and challenge themselves to get as many perfectly exposed pictures as they can in 1 hour. Don't cheat by using auto ISO, either!
By the end of this article, you should have enough tips to at least get you started on shooting entirely in manual mode. You may just surprise yourself at how easy it can be.
Elements of Exposure
Before I continue, let me step back and briefly cover a very important topic. In photography, there are three elements of exposure.
1. Shutter Speed is the length of time the shutter stays open. The longer the shutter stays open, the more light is allowed to reach the camera's sensor. Typically, with action shots we want a fast shutter speed to freeze motion. But there are also times when we want to slow down the shutter to add a bit of motion blur, for example with waterfalls.
2. Aperture is how wide the opening of the lens is during the exposure. The wider the opening, the more light is allowed to enter. Aperture is what controls the "depth of field" in your shot. That is, how much will be in focus. The wider the opening, the narrower your depth of field will be. This is measured by the f value on the lens. The smaller the f-value, the wider the opening on the lens. The bigger the f-value, the smaller the opening on the lens. This may seem backwards at first, but the way it is measured is simple:
f-value = (focal length of the lens) / (diameter of the opening)
For example, if you have a 100mm lens, and the opening of the lens is 25mm, you will be at f/4. However, if you zoom in to 200mm and keep the opening the same size, you will now be at f/8.
3. ISO or previously referred to as ASA, is the sensitivity of your film or sensor to light. It will take more light at a low ISO to properly expose an image than it will at a higher ISO. However, higher ISOs are more prone to noise (or grain if you are using film).
All three of these values mix together to get a specific exposure value. Any time we want to adjust one of these elements, we need to compensate by adjusting one of the others. For example, let's say we know that we are getting the correct exposure with the following settings:
Shutter speed: 1/100 sec
Aperture: f/5.6
ISO: 400
Now let's say that we want to increase our shutter speed to 1/200 sec, but we don't want to change the exposure. In this case, we must compensate by also adjusting one (or both) of the other two settings. One example, would be to simply double the ISO. Since we are letting in half as much light by the shutter speed staying open half the time, we can make the sensor twice as sensitive to the light it is getting. So one solution would be as follows:
Shutter speed: 1/200 sec
Aperture: f/5.6
ISO: 800
These two settings will result in exactly the same exposure value, except with a faster shutter speed. Since this isn't a lesson on exposure (exposure is a huge topic on it's own) let's move on...
Sunny 16 Rule
For someone starting out learning to shoot in manual, this is the greatest tip you will ever hear. When you are outdoors, on a sunny day, if you put your camera at an aperture of f/16, your exposure will be correct if your shutter speed is the inverse of your ISO. For example...
Shutter speed: 1/100
Aperture: f/16
ISO: 100
Shutter speed: 1/200
Aperture: f/16
ISO: 200
Shutter speed: 1/400
Aperture: f/16
ISO: 400
Aperture: f/16
ISO: 400
All of these settings will produce the perfect exposure value for a sunny day. I said it was easy, right?
Now what if we want to use a different aperture? Well, this is where math comes in again. Any change in aperture will require compensation from one of the other values. But, since this isn't a lesson on calculating exposure, these calculations are out of scope.
What if it isn't sunny? Are there other rules?
Yes! We can include the following as well:
- Snowy/Sandy f/22 rule
- Overcast f/8 rule
- "Slightly" Overcast f/11 rule
- "Heavy" Overcast f/5.6 rule
- Sunset f/4 rule
For each of these conditions, the same principle applies. As long as the shutter speed and ISO are inverses of each other, using the aperture defined in the appropriate rule above will get you a pretty good starting point for getting the right exposure.
Conclusion ... and your challenge!
You now have the tools you need to put your camera in manual mode and get some great shots! So here is your challenge. Take an hour, put your camera in manual, get outside. In that hour, try to get at least 20 pictures worth sharing. I would be happy to see them!
