Pre-Photography 101: The Numbers, Part 2

Earlier I did an introduction into the Numbers of photography.  The discussion introduced you to numbers such as ISO, Shutter Speed and Aperture or Lens Opening.  I closed earlier by saying we would talk about them further.  Now is the time to talk further.  In this segment we’ll talk about Shutter Speed.

The shutter is the devise in the lens that opens and will let light enter the film or sensor.  For the purpose of this discussion and so I don’t have to add the antique word “film”, let just refer to the image sensor or sensor. 

The shutter operates as a function of time.  The shutter opens and stays open for a period of time, then closes.  Now you’re probably going to ask: Why vary the length of time the shutter is open?  Why do I care?  Let’s explore this time concept.

Picture yourself standing at the side of the freeway (Get it – picture yourself).  As you look across the lane of traffic, cars fly by at freeway speed.  I ran some quick numbers and it just so happens that a vehicle traveling at 60 miles per hour on the highway moves at a rate of 88 feet in one second.  Don’t believe me?  Run the numbers. 

Now let’s go back to you standing on the side of the freeway.  In this case, you stand still at the side of the highway with your eyes closed.  Your closed eyes represent the closed shutter on your camera.  As a car drove passed at 60 miles per hour or 88 feet per second, you opened your eyes for one second without turning your head, and then you close your eyes.  How far does the car travel in the one second your eyes are open?  Right – 88 feet! 

Now let’s get back to the camera.  If the shutter was opened for one second and the camera remains still, the car would travel the same 88 feet during the time the sensor was exposed to the light. 

How would the car appear in the image?  You would see the car as a blur.  Why?  Because the shutter was open for one second and recorded the car traveling 88 feet.  Let’s try this again.  Only this time the shutter stays open for one-half of a second.  How far does the car travel in one-half second?  The answer, I hope is easy – 44 feet.  Now ask yourself, which image has more car movement or blur.  The one second exposure of course.  Lets’ create a table of shutter time and distance traveled for this car.

Time OpenSeconds	Distance (FT)
1	88
1/2	44
¼	22
1/8	11
1/16	5.5
1/60	1.46
1/250	.35
1/500	.176
1/1000	.088

 

Can you visualize what’s happening here?  The shorter the shutter time, the shorter the travel distance of the car during the exposure time.  So In 1 second the car travels 88 feet and in 1/1000 (right that’s one thousandth of a second), the car travels .088 feet or 1.05 inches.  Where do you see more blur; the 1 second exposure or the 1/1000 second exposure?  You guessed it – the 1 second exposure.

Lets’ add another word to our vocabulary.  The car travels 88 feet during the 1 second exposure and we describe the appearance of the car in the image as “blurred”.  When the shutter time is only 1/1000 of a second and the car travels .088 feet or just over 1 inch, the car would appear not so blurred or “sharper” in the image.

Special Note:  This example is given to explain the concept of Shutter Speed.  If you attempt to duplicate this example in daylight, vehicles may not appear in the image.  This is due to the speed of the vehicle not allowing exposure to register in the image.  This example may best be seen in low light conditions.

So for a moving subject in a photograph, in order to minimize the “blur” or to make the subject appear “sharp” we want a very short shutter time.  Or we want the shutter to open and close very quickly – Fast! 

If you’re following me here, you might now ask the question “Should I always shoot pictures with the fastest shutter speed?”  The answer – Maybe.  I can hear it now – Tom, can’t you just give a simple answer to my question?

Well, first we need to remember, the shutter speed is another creative tool to control our exposure.  To answer your question: Should I always use the fastest shutter speed, I have to ask “What are you trying to accomplish in the image?”  If we’re talking about the car on the freeway and you want to minimize the blur, than yes, use the fastest or shortest shutter speed.

Now let’s go for a walk in the woods where we happen upon a waterfall.  You take a picture of the waterfall using a fast shutter speed and the tumbling water appears very sharp.  It almost looks like it’s frozen in time.  How cool is that!  What happens when we use a long shutter speed say ½ second or 1 second.  The moving water is blurred and turns a silky white.  Photographers have often used long shutter speeds to create a soft appearance or to enhance the mood of the image.  So which image is better?  You tell me. 

Sometime when you want to play with different shutter speeds, put your camera in to the “Shutter Priority” mode and try different shutter speeds.  Will you need that camera manual to figure out how to find and set the camera to shutter priority?  Probably!  You might want to keep that manual handy.

The issue is: You now have another creative tool in your photographer “tool-kit” to change the appearance of an image and to change it to suit your desired end result.  Why don’t you think about where you would use a fast shutter speed or a slow shutter speed and post or email your suggestions?

In the case of the waterfall, what looks better?  One thing I’ve learned; What I think looks good, may not look good to the person standing next to me.  If out of 10 people 8 like the end result, that’s one thing.  Are the other 2 people wrong who don’t like the result?  No, they just don’t like it and they are entitled to their opinion.  And that’s all it is – their opinion.  Give changing the shutter speed a try.  We’ll talk later.

Pre-Photography 101: The Numbers

In my previous post (Pre-Photography 101), I talked about some basics. One of which was Exposure. So let’s look at Exposure a little closer. Today’s cameras are great for measuring the amount of light entering the lens. This is where things get started – measuring the amount of light. Before we get started, let me ask you to do a couple of things. First, reach into that junk drawer. You know the one that has all the pens, dead batteries, paper clips and expired coupons. In that drawer dig way to the back of the drawer and pull out the manual for your camera.

There are three sections I’d like to read about. First, find the instructions to change your camera’s ISO Setting. Your camera ISO is probably set for “Auto”; change the ISO setting to 100. Now don’t put the manual away. If you want to return that ISO setting to “Auto”, you may need the instructions again. You’re going to ask me why you should do that. And, Should I always shoot with the ISO set at 100? The answer is NO. Your next question will be why not? For right now, cause I Said So (LOL)! I’ll talk more about ISO and answer those questions in another post. Setting the ISO to 100 will simply keep all the light readings set for the same light scale reference. If I tell you any more, I’ll likely confuse things.

The second area to look up, is how to control the flash on your camera. There should be a flash mode selection feature on a setting dial or a menu tab. Please set the flash to “Off”. I’ll bet you didn’t know you could have so much control over your camera – did you? Don’t you feel powerful with all this control!

The third area in the manual to look at is the description of your display information. You need to know what information is shown in the display and where to look for it. The reason to look at your camera manual for this is because I don’t know what camera make/model you have. So I can’t tell you where the information is displayed. I’m simply going to explain the numbers and ask you to watch how they change under different lighting situations.

Now that you know where the information is positioned in the display, you should be able to find the numbers that indicates the Shutter Speed and Lens Opening. The shutter speed is simply that – the length of time the shutter is open to expose the sensor. Shutter speed is measured in time. You may read something like 5s (5 seconds), 1/30 (1/30th of a second), 1/125 (1/125th of a second), 1/250 (1/250th of a second)….. are you getting the picture here? Yeah bad pun, I know. This number indicates how long the shutter will be open. So if the display shows 1/125, the shutter will be open for only 1/125th of a second. That’s a real short period of time! So which is a longer exposure time, 1/30s or 1/250s? If you’re having a bit of a struggle here – the larger the bottom number in the fraction, the shorter the shutter speed. So 1/30s is a longer exposure than 1/250s.

The next number you will notice will look something like: 2.8, 4.5, 5.6, 8.0, and 11.0. These are referred to as “f-stops”. An f-stop is the opening size of the lens. So what does the number mean? You ask. If you really need to know, it’s not a measurement like inches or millimeters. It’s the ratio of the lens opening and the distance from the lens to the film or sensor plane. Aren’t you glad you asked?

The point to understand about the f-stop is the smaller the number, the larger the lens opening. The comment I expect to hear is if the lens opening is larger why isn’t the number larger? It goes back to the simplified definition given earlier. You just have to get used to remembering the larger the number the smaller the opening.

So what’s the relationship between the two you ask? As a photographer you can use shutter speed and lens opening as creative tools. I’ll explain more about them as tools in another post. But for right now, let’s do a little exploring. If you have a dark area in the house or if it’s night time, aim the camera at a dark scene. Look at the exposure numbers in the display. You should see a very slow shutter speed. Depending on the light available or not available, you may see a shutter speed as slow as ½s, 1s, 2s or whatever the time is. In fact, why not write the number down. In addition, look at the lens opening number also known as the “f-stop”. You may see a number like 2.8, 3.5, or 4.5. Going back to my lens opening discussion earlier, these numbers should be small numbers, meaning a large lens opening.

Now try the same exercise in a well lit area indoors during daylight. Indoors with a lot of light, you may get shutter speed numbers like 1/15, 1/30, 1/60 and an f-stop like 3.5, 4.5 or 5.6. Again based on the brightness of the scene, the numbers will vary and I can’t guess them from here. OK, if it’s daytime and you aim your camera outdoors in your yard, you may see shutter speeds like 1/125, 1/250, 1/500 and f-stops like 5.6, 8.0, 11 or 16. These are very fast shutter speeds and the lens opening is getting much smaller. Remember the bigger the lens f-stop number the smaller the lens opening.

So what is going on here? In dark situations the shutter speed is very long and the lens opening is large. In these dark light levels, the camera metering system is slowing the shutter and opening the lens up to let as much light enter the lens and hit the sensor to get an acceptable exposure. Going to the daylight scene, the metering system has set the camera with a very short shutter speed and set the lens opening to a very small one. Again the metering system is using settings to control the amount of light directed to the sensor.

If you’re beginning to wonder “how does the camera know how to set these lens settings in these light situations”, then you’re making headway. It’s all in the metering system measuring the amount of light in the scene and the algorithms written and programmed into the camera software for exposure control. For right now, don’t worry how the algorithms work. If you’ve begun to understand the change in shutter speed and f-stops, then you’re on your way. This is the very basic start to understanding exposure.

So congratulations, you’re on your way! Oh you didn’t think you’d know everything by now did you? Oh and don’t forget to go back and return your camera setting to where they were before I asked you to change them. That will give you more practice reading the manual and getting familiar with your camera settings/menus.

So now that we’ve talked about those numbers, pay more attention to them as you take pictures. Just begin to notice how they change as the amount of light changes. Come back in the next couple of weeks and we’ll talk more!

Pre-Photography 101

So many people I speak with are often confused about how photography works. So I thought some basic info might be helpful. The intention here is to help you get better results with the camera in your phone, your point-n-shoot camera or a Digital Single Lens Reflex camera (DSLR). This is going to start off real basic. In later postings we’ll get into more details and more advanced techniques. One great place to start learning about photography is to spend some time reading the manual that came with the camera. Guy’s, this is one time when it’s OK to read the manual!

So what makes a good photo? There are two components to a good photo: Proper Exposure and Composition. That’s really all there is. Let’s look at each of these in basic terms.

Proper Exposure

A camera is simple; light enters the lens and has a photo-chemical reaction with film or creates an output from an electronic sensor.

In the case of film, you have to take the film somewhere for chemical processing. The film after processing then can be printed onto light sensitive paper, creating the final print image.

In your digital camera, light again enters the lens, but now it activates a photo-electric sensor. The sensor then converts an electrical signal to a digital signal (zeros and ones). The digital signal is then stored on digital storage media (a.k.a. memory card) in the form of a computer file. Once the image is captured as a digital file it can then be stored on a computer or transferred to a digital printer. The digital printer can be a home printer or a commercial printer at a photo lab.

In order to achieve proper exposure you control the light entering the camera in three ways: focus, time of exposure and the lens opening size. I mentioned focus from the standpoint of controlling the sharpness of the image. There are other aspects of exposure that control image sharpness, but more on that later. The two major factors dealing with exposure are the length of time the subject is exposed and lens opening size. That’s all there is to control.

Most people using a camera either don’t understand camera exposure or don’t want to understand exposure. But it simply relies on knowing how much light is coming into the camera and how to adjust that amount hitting the film or sensor. You or the camera electronics control that amount of exposure by adjusting the time of exposure or the lens opening.

“But I have all these controls on my camera, What do they do? All of those buttons or camera settings are there to control exposure. They have specific ways to give creative control over the exposure or to compensate for light variations.

Most people don’t understand the relationship between exposure times and lens openings. Each of these can be used to control the exposure and give the picture taker some creative control. I’ll spend some time talking about the relationship of exposure time and lens opening in a later posting.

Composition

OK, so we just talked about camera exposure to create a good picture, let me introduce you to the second concept used to take a good picture – composition. Composition is simply arranging your subject in a manner that is pleasant to look at. For example, what is better to look at; a photo of your friend with their head in the picture or with their head chopped off at the shoulders? If your intention was to show the details in the shirt or blouse, then you may not need the subjects head in the photo. If the intention was to show how wonderful the subject looks, then you probably want their head to be seen in the photo.

Lets’ work with the later concept here, that’s to show how wonderful the subject looks. That means you will point the camera at your subject and aim the camera up, down, left or right to position your subject so they are seen in the view finder or the LCD screen. Now you’re ready to push the shutter button.

Putting It All Together

So, you’ve properly exposed the camera and you placed your subject in the composition and created a picture. Now you’re asking – is that all there is? Well not exactly, but this is a good start. As I mentioned earlier there are a lot of other things that can be done or controlled to make your pictures better. I’ll try to spend some time talking about these techniques later. So come back in a week or two and I’ll give you some more information about good photography. If you have any questions about this little intro, email me at athomasimage@sbcglobal.net. I’ll do what I can to help or answer your questions.