Digital Camera Primer
By Tom Roberts
Considerations when shopping for a camera.
Cost.
Determine how much you are willing to spend on a camera. Cameras are constantly improving and the cost is constantly dropping. Today's digital cameras are equal to film cameras in image quality and features. The selection is enormous and new models are appearing all the time.
Camera size and features.
Do you need a camera that will fit in your shirt pocket or one that is larger and has more creative controls? Is a zoom lens important to you? If so, how much, 3x, 10x?
How much Pixel resolution.
The answer is, how big do you need to print your images.
My printer will handle letter size paper. So, 8x10 is the maximum standard size print I can make. I have determined an 8x10 is the maximum I will need.
My camera has a 3 megapixel sensor, at 150 pixels per inch (ppi) printing resolution, which I have determined to be satisfactory for my needs, I get a 13.5”x 10.25” image. This leaves me sufficient room for cropping and rotating the image.
I have resized and enlarged a cropped image to 11x14 with no noticeable degradation.
3 megapixels is right for me. If you have a larger printer and need larger prints, more megapixels would be right for you. If you are only going to print snap shot size pictures or just send photos in e-mails, fewer pixels will do the job.
Flash.
The camera flash should be able to take a group photograph in a normal sized room. Generally a distance of 10 to 12 feet. This distance should be considered a minimum.
Red eye is a product of the flash being to close to the axis of the lens. If you are buying a small camera, this is something you will have accept. Fortunately, redeye is easily correctable in most image editing programs.
Automatic Operation.
The camera manufactures have done great work in making the Auto mode perform property. I find, I stay in Auto mode about 90% of the time. There are situations where I want to have control over flash, focus, shutter, aperture, etc. Whether these features are important to you depends on your experience level and the amount of effort you want to put into the photographic process.
Ergonomics.
Once you have narrowed the field, go to a camera store (department) and physically hold the cameras you are interested in up to your face and try to determine if it is a comfortable fit for you. Look through the viewfinder to be certain the image is crisp and clear. Are all of the controls easily accessible. Does it appear to be durable, or cheaply made.
Setting up and using the camera.
Auto Mode
Most of the time I leave the camera in Auto mode. The camera makes all of the technical decisions, all I have to do is compose the picture and push the shutter button.
Camera companies have programed their cameras to take a good photograph when the shooting conditions are considered normal or average.
These would be outdoor situations and indoors using a flash. Or indoors where there is adequate available light.
Program Mode
I have the Program mode set up to change only the light meter and auto focus modes. Switching from Auto mode to Program mode gives me control over the two situations that generally are the most troublesome. Cameras (computers) don’t think or evaluate, that is up to you.
Light meters
The most common situation that deviates from average are scenes where the subject is backlighted. The background is brightly illuminated and the side of the subject facing the camera is in shadow.
Some cameras have a backlighting mode that will increase the exposure to retain detail in the shadows. If your camera doesn’t have a Backlighting mode, follow these guidelines. If the subject is fairly distant from the camera, increase the exposure by 1 f/stop (double the exposure). If the subject is close to the camera, increase the exposure by 2 f/stops and turn on the flash if possible.
Other situations that will confuse the exposure meter are, scenes that are predominantly light, such as light colored sand at the beach or snow, light reflecting off of water. Opposite that is where the scene is made up of predominately dark tones. A black cat in a coal bin comes to mind.
Sunsets or night pictures where you are more concerned with the mood of the picture, rather then trying to record a full range of detail.
Exposure compensation is generally accomplished from a menu in the camera.
With a digital camera it is easy to evaluate a picture using the LCD screen and retake the it if the results are disappointing. No more, do you think it will come out. In digital photography, experimentation is with out cost. If you don’t like it, erase it.
Light metering modes.
Evaluative Metering, also called Matrix Metering
The Evaluative system takes several readings around the frame and processes all of the information to arrive at the correct exposure. This system works very well most of the time.
Spot Metering
The light meter takes a reading of a small area in the center of the frame. Usually illustrated by a box in the view finder or the LCD screen. This method will allow you to get the correct exposure for a specific area of the picture. You will usually have to lock the exposure with a half press of the shutter button and then recompose the picture in the viewfinder before pushing the shutter button all the way down. A person sitting in a patch of bright sunlight with the rest ot the scene in deep shadow would be a candidate for a spot meter reading.
Center Weighted (may or may not be on your camera)
Reads the entire frame, gives more emphasis to the center. This method is reliable and falls some where between the Evaluative and Spot methods.
The image capture device in a digital camera has characteristics closer to slide film then negative film. Therefore over exposure of the high light region in the photograph is of more concern then under exposure of the shadow region.
As a general rule, the exposure meter in my camera will get it right most of the time. It will always put me in the ballpark where I can make final adjustments with Photoshop, no matter what metering mode I have selected.
Auto Focusing
As with the Light meter, Auto focus has Evaluative and Spot mode.
The Evaluative mode will evaluate several points within the frame and try to find an object with high contrast to focus on. This works well most of the time. However trying to photograph a landscape with a dominate tree in the foreground might pose a problem.
With the Evaluative mode turned off, the center frame becomes a spot meter for focusing. You can focus on the most important element in the picture and lock it with a half push of the shutter button.
Image Files
I prefer to keep the resolution set to the highest quality settings. However I have found there is some wiggle room for the JPEG compression settings. It is worth the time to experiment with your camera to find what works best for you.
For people who edit their own pictures, turn off all photo effects settings in the camera.
Enhanced color
Extra sharpness
Black & White
Digital Zoom
etc.
Shutter Lag
Pressing the shutter button half way down will cause the camera to make the exposure and focus calculations, continuing to hold the shutter button in the half down position will lock the settings. Push the shutter button all the way down when you are ready to take the picture. If you are trying to take actions pictures, you can pre focus at a distance where you expect the action to happen.
On my camera this method will reduce the shutter lag time from about 1.0 second to about .1 second. It can mean the difference between eyes open and a blink.
Accessories
Memory Cards.
Determine your requirements and purchase extra memory.
Batteries and charger.
My camera uses standard AA batteries and has plenty of power, so I have one set of rechargeable batteries and carry a set of alkaline batteries as a backup.
Tripod
A light weight tripod is handy for night scenes or including yourself in the picture.
Polarizing filter.
Good for eliminating reflections, the only filter you should ever need.
Memory card reader.
Since my camera has lots of battery power, I can load the images directly from the
camera to the computer without concern of draining the batteries.
If your camera is weak on battery power, a card reader is a good investment.
Viewfinders and LCD’s
Optical viewfinders see less of the picture then the camera captures. I am sure this is because people would rather see extra in the photo, then cut off a head. A situation called parallax, is the physical difference of the lens axis and the position of the viewfinder. As the camera moves closer to the subject, the more parallax is introduced and the less accurate the viewfinder becomes. In macro mode the viewfinder is all but useless. Single lens reflex cameras view the image directly through the lens and therefore have no parallax.
The LCD screen on the back of the camera gives an accurate representation of what the camera is seeing. It is good for composing the picture and for a quick evaluation after the picture is taken.
LCD screens are difficult to use in bright light conditions and I have purchased a hood to use on these occasions.
Batteries
I prefer standard batteries (AA etc.) to proprietary batteries. More battery power is always preferable. My camera holds 4 AA batteries and has plenty of power for long shooting situations.
I use rechargeable NiMH batteries that will recharge in 100 minuets at fast charge and 6 hours at slow charge.
As backup I carry a set of Alkaline batteries that will serve in an emergency and are available anywhere.
Miscellaneous notes.
The cameras self timer can be used as an effective cable release when making long exposures. Pushing the shutter button, even with the camera on a tripod, can introduce camera shake.
When using the self timer, do not stand in front of the camera when you push the shutter button. The camera will focus on you rather then the scene you want to photograph.
There is no cost associated with experimentation and the knowledge gained is very rewarding.
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