Photo Talk: Exposure Simplified - The Big Three

Whether I am at Yellowstone National Park, a local zoo, or some other type of tourist area I am seeing a huge increase in DSLR users. I am always curious as to how the photographer is shooting the scene, especially when I see a flash being used on a scenic mountain scene. So it is not unusual for me to strike a conversation with a fellow photographer or take a peek as what mode their camera is in.

Sadly many people are shooting in Program Mode and dont know how to change their ISO. Often I find people do not understand f/stops, shutter speed, ISO and how they work together. My intention of this posting is to try and simplify how aperture, shutter speed, and ISO work together. Knowing a bit more can help you create top quality images.

ISO
ISO stands for International Organizatoin for Standardiszation. It is bascially a system that establishes standards. The ISO standards are used when refering to film speed. The term film speed is really what we want to talk about when we talk about ISO. I think it is easier to understand and remember. Ah...the good ol film days!!

What does film speed mean anyway? It is bascially a way to decribe a sensitivity to light. A slower film speed means that it takes longer for light to burn through the film. The faster the film speed means it takes less time for light to burn through the film. With that said an ISO or FIlm Speed of 100 would be considered slower than an ISO or Film Speed of 1600.

Of course in digital photography we are not shooting film so what gives?? Well the sensor is your film in the digital world. Setting the ISO, for lack of better terms, sets the sensitivity of your sensor...its sensitivity to light. So again if you set the ISO at 100 your sensor will need to be exposed to light for a longer period of time than if you used an ISO of 1600.

You have probably heard of film grain. That is when the detail of the image becomes less sharp and sometimes even hazy. The lower the ISO the better quality image and less grain you will receive. On the other hand a higher ISO is likely to result in increased grain levels. To some degree grain can be control with proper exposure. Nevertheless, the general rule of thumb is the higher the ISO the less quality image.

Really that is about it. In the digital camera world ISO is refering to the sensitivity setting of your sensor and how much light it will need. So if ISO 100 needs more light than ISO 1600, how do we control how much light gets exposed to the sensor? That brings us to the next two of The Big Three.

Aperture
In optics aperture is a hole or opening in which light travels. The larger the hole, the more light is allowed through the lens. In this case the more light allowed through the lens to be exposed on your digital sensor.

How is the size of the opening measured? To start, just so you know, I dont know why they number it this way but they do. On a lens the aperture is measured by f-numbers. The larger the f-number the smaller the opening. The smaller the number the larger the opening. Check out the illustration.

You have probably heard that aperture settings determine the depth of field. Depth of Field (DOF) is bascially the portion of the scene that appears sharp in the image. Lets say you are taking a portrait of someone and you desire to have the background blurry but you for sure want your subject sharp. If you use a f/2.8 which is a rather large aperture the DOF will be short and the the background will be blurry. But be careful. Your DOF could be too short and the sharness could start falling off sooner than you would like and the result could be that the subjects hair line is not sharp. The answer? A smaller aperture setting. I tend to shoot portraits between f/5.6 and f/8, depending how much I want the background blurred. The smaller aperture also helps ensure my subject is sharp and completely focused.

So lets say I want the opposite result. Lets say I am taking a photo of a cool rock formation in front of a waterfall that is slighty in the distance. Lets say I do not want the background (in this case the waterfall) blurry, I want it in focus. You guessed it!! Then I want to set my aperture at a rather small aperture like maybe f/18 or even f/22. With the smaller aperture the scene sharpness will be longer. I will have the foreground rocks and the background waterfall all in focus. Awesome!!

So aperture is the opening that allows light to hit the sensor. If we are shooting at f/4 we can see the opening is rather large. How do we control how long that light is exposed to the sensor? That leads us to the next of The Big Three.

Shutter Speed
Shutter speed is the length of time the shutter is open to allow the light being exposed through the lens to hit the sensor. If light is very intense in all likelihood it will need to hit the sensor for a very short period of time. Therefore you will want a fast shutter speed, maybe even something like 1/1000 th of a second. If the light is very low you may need to expose the sensor to light for a rather long time, maybe up to 3 seconds.

Depending on the size of lens and how far you are zoomed in, you can typically hand hold a camera at shutters 1/60th of a second and faster. Slower than 1/60th like 1/10th or 1 second you will need a tripod or other means to support your camera to avoid a blurry image.

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Hopefully these simple explanations are beginning to help you see that The Big Three are rather easy to understand and a combination of the three makes for well exposed image which in turn makes for a quality photo.

There can be a lot more time spent on explaining The Big Three. My intention is to shed light on the basics and help you see how they work together.
So lets talk through a couple examples.

Example 1
Lets say I want to take some photos of nightime cityscapes with the city lights illuminating the streets of the city. I am not going to use a flash and I would like to have images of high quality with little or no grain. I set my ISO to 200. Based on what I have learned an ISO 200 is not very sensitive to light and will need to be exposed for a longer period of time. In all likelihood I will need a tripod.

With the ISO set at 200 I need to next decide on my aperture setting. I want to make sure my DOF is not too shallow yet at the same time I do not want all of the background in focus. I choose f/11.

Since I have a less senstive ISO and a somewhat smaller aperture selected I may have to choose a slower shutter speed to make sure everything is exposed correctly. Depeding on the actual amount of light the shutter speed will vary. To follow through with the example I will say I will need to set my shutter speed at 2 seconds.

ISO - 200
Shutter - 2 Seconds
F-stop - f/11

Example 2
It is late afternoon and I am taking photos of animals at a zoo. Not only is is later in the day but the animal I am photographing is in a shaded area therefore I have limited light. Typically during the daytime hours I would choose a lower ISO like 100 but I am not so sure that is going to work today. When taking photos of animals you will want a little faster shutter speed since they move unpredictably and faster than you think. I dont want blurry shots so I will need a faster shutter speed.

To get a faster shutter speed to work in this slightly lower light situation I will most likely need to use a little higher ISO. I set the camera at ISO 800. I know that I have selected a little more sensitive ISO so it will not need to be exposed to light nearly as long. To control this I will need to set my shutter and aperture accordingly.
I do want a faster shutter speed so I set it at 1/500th of a second. Although my ISO is sensitive, I have selected a faster shutter speed. The light will be exposed for a very short period of time so I will have to let more in through the aperture. Again, depending on the actual situation the f-number will vary. To follow through with the example I will say I set the aperture at f/4.

ISO - 800
Shutter - 1/500th
F-stop - f/4

Experiment...shoot, shoot, shoot. Since you are shooting digital you will not waste film. Try shooting the same scene in different ways. In no time you will feel comfortable to turn your camera mode dial off of Program and begin shooting in Shutter Priority Mode, Aperture Priority Mode, or even Manual Mode.

Photo Talk: The Skinny on Sensors

To start I must say I was rather surprised this weekend when I found out that people are actually reading my blog and liking it. A big THANK YOU!!, to you.

When I discuss a topic I like to keep it as simple yet informative as possible. I find some sight over complicate things or get too deep in the subject. I like to think there are a lot of people that want to learn more but do not want to read something that takes a college degree to read.

With that said, lets talk sensor size, mega pixels, and the clarify that more is not necessarily better, but bigger is better.

Most of you probably remember what 35mm film looks like, I mean in reference to its size. The negative is the original, your master image. The data captured on a 35mm film can be enlarged but you will get to a point where the clarity is lost and the enlargment starts to look not so good. The negative is 35mm wide, about 1 3/8 inches. When you print a 4x6, 8x10, and 11x14 print from a 35mm negative you can see the clarity begin to diminish.

Do you remember the old 110 film and how small it was? It was 16mm wide. In this case your source is a little more than half the size of a 35mm. You can image the clarity loss as you print a 11x14 print from a .63 inch master.

I tell you all this to help explain what is going on with digital sensors and why more megapixels is not necessarily better. Sure the marketing will tell you it is, they want you to buy the camera. But really...sometimes less is more.

Here is a little image breakdown to show you comparison of sensor size. Of course this is not actual size but I am sure you will get the idea.

A sensor that is equivilent to a 35mm piece of film is called "Full Frame Sensor". Professional camera bodies are the ones that will have a full frame, or 35mm wide sensor and will cost you some serious cash. The most common size sensor in Digital SLR's is the APS-C which is 22.7mm wide. Many of the compact cameras have sensors that are 5.3mm wide. You can see already the difference in the size of your master image and the impact it will have on how large of an image you can really print.

Now that we have established some groundwork in sensor size...lets talk megapixels.

Don’t be fooled to think more is better. An APS-C sensor is 22.7mm wide and its size does not change with the addition of more and more megapixels. For the Mfg. to go from 10 MP to 15 MP the actual pixel must be smaller to crunch them on the sensor. In this example, 5 million pixels squeezed on the same sensor that once held 10 million.

Each pixel gathers light and exposed to color. One would think that having more is better. In fact you must remember that each of those pixels are now smaller, meaning it could take more light to maintain or increase effectiveness.

Everything I have read about the Canon 40D vs the Canon 50D indicates that the 40D is better in higher ISO noise. The 40D is 10.1 MP camera and the 50D is a 15.1 MP camera.

The big megapixel cameras (21.1 MP) for Canon are the 1Ds Mark III and the 5D Mark II which have full frame (35mm wide) sensors. Interestingly the other pro body from Canon (1D Mark III) which has an APS-C (22.7mm wide) sensor, has only 10.1 MP’s.

I think it is easy to conclude that more MP’s is not necessarily better. I am convinced the camera companies are building what you are willing to buy. As long as people think that more MP’s are better, they will continue to build and design entry level and advanced amateur cameras with more MP’s.

A good example is the compact camera world. Look at the size of the sensor in most of these cameras. It is like 5.3mm wide which is less than a ¼ inch.

Learning what you have, it is easy to conclude that 8MP on a DSLR (APS-C sensor) is much better than 8MP on a compact camera sensor.

I have had two compact cameras. My first was 2.1MP and the latest is 7MP. I have taken far better images with the old 2.1MP by far.

The two images above were taken with my Sony 2.1 MP camera. In a small compact camera I personally think less MP's are better. A 2.1MP image will make a good 4x6 print. Much bigger than that and quality drops.

The Canon 300D I took to Africa in 2007 was a 6.1 MP camera. It is my opinion that in most cases you do not need much more than 8 MP's unless you do a lot of cropping.

Please remember, a DSLR sensor is nearly 4.5 x's larger than a compact camera sensor. Even though a compact camera may have 8 MP's, the potential for top image quality is just not there.

Here is a little tool to help associate MP's with print size.

The point of this blog is to help you become informed and to encourage you to do a little more research as you seek to purchase what may be your first DSLR. Do your research before you buy. There are several great review sites.

Fred Miranda

The Digital Picture

SLR Gear

Digital Photography Review

Cross reference the reviews. Don't rely on one review to make your decision. You are investing a fair amount of money and you want to be confident in your purchase.

Even as I plan on upgrading, I will choose the Canon 40D over the Canon 50D. I am not looking for MP’s, I am looking for top quality.

Photo Talk: Not Taking Zoo Pictures

At first you might think this is some kind of posting about how it is only a cool photo if it is taken in the wild. On the contrary...I am not one who thinks taking a photo in a zoo is wrong. As far as I am concerned, I love to capture God's creation and help express its beauty...zoo or in the wild.

This post is more about taking photos in a zoo and not having the photo look like a "zoo" photo.

I have seen many posts at various websites where the photographer has taken lets say a photo of a lion and forgot to exclude rocks, fences, and people. The shot may be a winner with an expression or action that is priceless but with all the other distractions it turns out not to be a "money shot".

I am still learning everytime I go off to a zoo. Not only do I learn more about photography but I also learn more and more about what zoos in my area are even worth going to.

I like to see large, natrual looking enclosure and evidence that the animal is well taken care of. I also like to check out the lighting situation and make a plan as to what animal I want to photograph when.

It is funny...almost every zoo I go to says - "The bears are more active in the early morning and mid evening". It cracks me up because the zoo does not open until 10 am and closes at 5 pm. LOL...I can never figure out why they tell me such things.

So anyway...after you spend a little time figuring out what you want to do and when, it is time to crack open the gear and get rockin.

You best have a decent size zoom. Something you can get nice and tight with if need be. I have a Canon EF 70-200mm f/4L which can do the trick sometimes but there are times I add a 1.4 teleconverter to get a little distance.

Recently I added a Tamron SP AF200-500mm F/5-6.3 Di LD (IF) Ultra Zoom to my arsenal. I am very pleased with the zoom factor but it is not nearly as clear as my Canon L. I knew that when I purchased it so there is no real surprise.

I would certainly plan on using at least a monopod. Once you get used to shooting with one they are really quite handy. I personally would recommend a ball head of some sort so you can stay versatile with horizontal and vertical shooting.

When I use my bazooka...oh...Tamron 200-500mm it is certain I will need a tripod. I have tried to hand hold this thing but it is just better with a tripod.

Depending on the effect you are looking for, I generally try and stick with fairly fast shutter speeds - at least above 1/800th. You never know when an animal is going to blink, move, or turn their head.

Dont be too afraid of mid day lighting. Depending on the animal and how you adjust your exposures, it can really add character to the shot.

Another good practice it to switch your camera to burst mode. I like to take 2-3 shots in a row so I can ensure I am catching what I want to catch. If you have luck like me the first shot the deer closes its eyes. The second shot it sticks out its tongue. Maybe the third shot will be the winner.

I do a lot of zoo shooting. If you have any questions please feel free to drop a line.

Keep your strap around your neck and happy clickin!!