Indeed, there is an embarrassment of riches in the variety of good cameras available today. Perhaps that is what makes the decision so much harder for consumers. Each type of camera, each manufacturer within those types have advantages and disadvantage. There are so many pros and cons that I cannot really hope to cover them in a single article. Remember, that no camera is perfect. What will work well for one person may not complement another photographer’s usage.
- Aperture – Aperture is perhaps one of the most confusing concepts that a new photographer is confronted with when looking at cameras. Basically, the aperture is the opening in the lens, or camera depending on the design, which controls the amount of light that gets to the imaging plane. It is typically an iris mechanism made of interlocking metal blades which changes in size as you adjust the aperture control. Aperture is generally used for two things in photography. The first is increasing the amount of light that strikes the sensor in low light situation. The second is controlling the how remains in focus with in the frame besides the subject. The amount of in focus area of a photograph is called the depth of field.
In the interest of space, the basics that you need to know about aperture are:
(1) The larger the physical size of the aperture
a. The more light which gets to the sensor, and
b. The less stuff in the frame besides the subject that will be in focus (less depth of field);
(2) The smaller the aperture:
a. The less light that gets to the sensor, and
b. The more of the frame besides the subject that will be in focus (greater depth of field);
The aperture number is based on a ratio to the focal length “f”. This means that the relationship between the physical size of the diaphragm opening and the f-stop number is inverted. f/1.8 is larger than f/4, which is larger than f/8, which is larger than f/11, etc.
(4) Stopping down means closing the aperture (moving to a bigger f-stop number), i.e. going from f/2 to f/22 is switching from a very large opening to a very small opening;
(5) Opening up means making the aperture bigger (moving to a smaller f-stop number), i.e. moving from f/16 to f/1 is moving from a small opening to a very large opening;
(6) Some lenses have variable apertures listed, i.e. f/3.5 – 5.6 is a common variable aperture range. You will find these on consumer level zoom lenses. What this means is that your largest sized aperture is dependent on the focal length you are using at a given moment. If a zoom lens has a zoom range from 18mm to 200mm then your largest aperture that you can set will vary between f/3.5 at 18mm to f/5.6 at 200mm. You will not be able to use an aperture larger than f/5.6 at 200.
(7) Fixed aperture lenses have a maximum aperture that remains constant throughout the zoom range. A fixed 70-200 mm f/2.8 lens can have its aperture set to f/2.8 at 70 mm, 100 mm, 154 mm, 186 mm, and 200 mm focal lengths. Most f/2.8 fixed aperture zoom lenses are profession grade lenses that are fairly expensive. You will also find some f/4 fixed aperture lenses which are not quite as expensive and are targeted toward the mid-range or enthusiast market.
(8) You can change the aperture size depending on what you want to happen with your photograph. Some people seem to think that because a lens says it is f/1.8 that it can only be used at f/1.8. Far from it, most lenses are better stopped down a little from their maximum aperture.
- Aberrations – Aberrations is a term for odd things that turn up in a photograph due to various optical properties or compromises. Some of the aberrations that you will hear about are:
Chromatic Aberrations are fringes of color around objects.
(2) Flare are reflections of light sources off of the interior optics of the lens.
(3) Distortion is a warping of the shape of objects such as the circular effect you get with fisheye lenses. There are also pincushion and barrel distortions. Most lenses, particularly zoom lenses, will have some distortions. However, the better lenses will control them much better than lower quality lenses.
(4) Moiré is a false color pattern that can appear when photographing objects with a very finely textured, repeating pattern to it. Cloth is one example, screen doors is another where most people might see moiré, but it can also occur in stairs photographed from particular distances, cables on a bridge from certain angles, even bird feathers can produce moiré. Most cameras can produce it to some degree or another, although some cameras are more prone to it than others.
- Image Stabilization – Image stabilization is a feature that reduces movement and vibration which can affect the optical path of light. These vibrations can cause the subject to be less sharp than they should be otherwise. Stabilization is intended to help you get a sharper photograph by counteracting odd little movements in the lens that you might not be able to detect. The ultimate in stabilization is a really good tripod. However, you can’t always take a tripod with you. So camera and lens makers have developed optical image stabilization methods to help you out. Each manufacturer has their own system which adds to the alphabet soup on all lenses. You will see acronyms like IS, VR, OS etc. used to denote the manufacturer’s stabilization method. There are both in-lens stabilization techniques and in-camera stabilization techniques.
- Focus Speed – Focus speed is the speed at which the camera can acquire focus. This is particularly important when you want to photograph action. It is nice to have a camera that can acquire focus very quickly even for “regular” images as it is less time you have to wait for the camera before you can take a photograph.
- Focus Accuracy – Focus accuracy describes the accuracy of a camera’s focusing system. If a camera’s focus system is not very accurate, than your photographs will not be as sharp as possible. This can tie into interchangeable lens systems in that both the camera and lens will contribute to focus accuracy as well as focus speed.
- Viewfinders – Viewfinders are the little windows that you look through to frame your photograph. There are several kinds of viewfinders:
(1) Optical Viewfinders
are the kind that you find in most DSLR cameras. They consist of either a specially designed prism or a series of mirrors. Both methods transmit light from the lens to the eyepiece via optical methods. Their advantage is that you see exactly what light is coming through your lens. They also provide the largest and brightest viewfinders and provide the most accurate method of framing and judging action timing. However, they add some bulk to cameras, and the better ones also significantly contribute to the cost of cameras.
(2) Rangefinder Optical Viewfinders are a type of viewfinder that looks directly through the camera housing and not through the lens. They will usually have some marks in them to help with framing, but because they do not see through the lens there is always a problem with parallax offset when photographing close subjects.
(3) Electronic Viewfinders are little LCD screens that replace the bulky optical viewfinders’ mirrors or prisms. They are becoming much more common on compact and mirrorless cameras. Sony has even started using them in their “DSLR” equivalent cameras. Currently, electronic viewfinders are reported to have a certain amount of lag to them which makes timing critical action events more difficult than with an optical viewfinder. However, they are generally a less expensive technology to add to the cameras now. They will also get better as time goes on. It is not difficult to consider that electronic viewfinders may one day match the reaction speeds and accuracy of optical viewfinders. However, that day has not quite arrived yet.
Finally, I need to mention that many compact cameras these days do not have a viewfinder at all. Instead, you frame your photographs via the LCD screen on the back of the camera. All smartphones are like this as well. There is usually quite a bit of lag when you frame a photograph with the rear LCD. You also are not holding the camera in as stable a position as you would when using a viewfinder. Thus, the camera is more prone to movement, or “shaky hands syndrome” than a camera you hold to your eye to look through a viewfinder.
- Resolution – Resolution is the “megapixel” number that camera makers use for the one of their primary selling points. Their contention is that more megapixels are “better”. It is an easy number for people to understand and does give a good point of comparison. However, megapixels are really only part of the story you need to consider in a camera.
If two cameras have the same size sensor, but one has a higher resolution, than the higher resolution camera could resolve finer details than the lower resolution camera. However, resolution is one of those compromises that camera manufacturers have to make when designing their products. What they don’t tell you is that that a lower resolution camera might be a lot better in low light conditions than the higher resolution camera is in the same situation. This is because fewer pixels on a sensor means that those pixels are bigger than on a higher resolution sensor.
Bigger pixels generally means that they gather more photons of light. They are also spaced farther apart and thus do not produce as much interference or “noise” as a higher resolution camera might. To be honest, these days the sensor technology has matured enough that resolution is a lesser concern in deciding on a camera than it used to be. Most cameras have “enough” resolution to produce excellent 4″x6″ standard sized prints and can even produce excellent 8″x10″ prints. If you don’t need to print any larger, then don’t get too caught up over a camera’s resolution.
- Sensor Size – Sensor size is the actual size of the sensor in a camera and is related to the resolution as I described above. There are several sizes of sensors used today. They range from the tiny ones in smartphones, to slightly larger ones in entry level compacts, to larger sized mirrorless camera sensors, to cropped-sized sensors, and to so-called “full frame” sensors in the highest end DSLR cameras. In generally, image quality increases in direct relation to sensor size. Larger sensors have less noise, better resolving power, and better low-light characteristics.
Images Courtesy of Canon Inc.
Again though, the sensor size is a compromise decision. For example, you won’t find full frame sensors in very many smartphones because the sensor would significantly increase the cost of the phone. Conversely, full frame sensors are usually in big bulky DSLRs that you might not want to carry around all the time. There are some exceptions coming out these days to be aware of when shopping. One example is the Sony RX100. I believe that it has a full frame sensor in a compact camera sized body. Following are some common terms you will see regarding sensor sizes:
(1) Full Frame
means that the sensor covers the entire area of a frame of 35mm film. There were / are larger film and sensor sizes, but this is the term that has evolved for 35 mm sized sensors.
(2) Cropped Sensor really is any sensor smaller than a frame of 35mm film. It is called this because it acts as if you cropped into a small area of the 35mm frame.
(3) APS-C is a particular set of sensors sizes. They are cropped sensors that are approximately equal to an APS-C frame of film. APS was a Kodak film type that they marketed to consumers just before the advent of digital cameras. It was a little smaller than full 35mm film. Thus it was supposed to be a less expensive film type. It did not really catch on though. However, during the maturation of digital photography it was the initial size of sensor that was used for the first several generations of DSLRs.
APS-C sensors are still used in DSLRs today due to the economy of scale that manufacturers can get from producing them. More APS-C sensors can be manufactured off of a silicon wafer than full 35mm sensors can be manufactured. Hence, they are a good choice for those looking for really good image quality without the expense of full frame cameras. There are also other APS sizes used in cameras such as APS-H. Just understand that APS-C, APS-H, etc. are fairly large sensors, with excellent image quality characteristics that are the step below full frame sensors in size.
(4) Crop Factor or 35mm equivalent is basically a ratio that gets applied to lenses on cameras with smaller sensors so that you can compare the effective focal length to lenses on a 35mm camera. Thus, an APS-C camera with a x1.5 crop factor which has a 24 mm lens on it captures about as much in a photograph as a 35mm camera with a 36 mm lens on it (24mm x 1.5 = 36mm). Again, this can be a useful number, but don’t to get too hung up on it as it doesn’t tell the entire story. Perspective rendering doesn’t change due to the crop factor for example.
- User Interface (UI) – The user interface encompasses the physical controls as well as the menu layout. The UI is an important consideration because some cameras have a lot of functions, but they are buried in layers of menus. Others have dozens of buttons on them that can be programmed per the user’s whim. Don’t get a camera who’s UI you can’t figure out.
Image Copyright Craig A. Lee
Whew! That is a lot of terms and we haven’t even gotten into the cameras yet. However, each of those terms will have an impact on the sort of cameras that you look at. I will let this little dissertation set in for a bit. Then we will talk about cameras next time in Part 3.
About the Author
Craig Lee lives with his wife and son in the upstate of South Carolina. Craig has been an enthusiast photographer since 2007 when he got his first DSLR for Father’s Day. His photographic interests range from landscapes, to sports, to cityscapes , to abstracts with a tendency to integrate architecture found in natural surroundings. He has also been the official photographer for the Greenville Scottish Games since 2010.
Craig’s website is www.CaleeImages.com where you can find more of his work and a blog he needs to spend more time on.