Capture the Moment Monday

Dave Berry, Director of the Photography Department at Computer School for Seniors will be sharing his insightful Photo Tips with you every Monday for Capture the Moment Mondays.

4 DSLR Questions you were afraid to ask--Part 4

1.) What's the difference between evaluative, centerweighted and spotmetering?
All camera meters try to make some part f the frame appear as a midtone---right between very light and very dark. Evaluative metering divides the frame up into segments, compares the reading in each section, and decides on an appropriate pattern for determining exposure. Centerweighted takes into account all the light, but puts a heavy emphasis on the middle of the frame. Spotmetering uses a small percentage of the frame--often less than 5 percent and typically in the center, though some cameras let you link it to the active AF point while evaluative is best for most situations, centerweighted works well for subjects such as group portraits. For the most control, use spotmetering to choose the midtone.

2.) Why use a handheld lightmeter when I have all those choices in the camera?
Because most handheld meters let you set your exposure based on the light falling on your subject, called "incident" light. They're great when your subject is unusually dark or light which camera meters tend to over or underexpose. They also help get consistent exposures in scenes with a wide range of tones. For an incident reading, hold the meter at the point on your subject where exposure is most critical, such as the face, and point it at the camera position. Many handheld meters can be set to read reflected light ad flash intensity, too.

3.) How do I tell how far my flash will reach?
By the Guide Number, assigned to almost all built in and shoe mount flashes and listed in feet, meters, or both in the back of you camera or flash manual. The GN tells you how far your flash will carry at a given aperture or what aperture to set for a given distance. Just divide the GN by either distance or f-number. For example, if a flash has a GN of 80 at ISO of 100, it can reach up to 20 feet with a lens set to f/4. If you want to shoot at 40 feet at the same ISO, you'd have to open your lens to f/2.

4.) My flash has TTL and Auto settings. What's the difference?
The TTL setting controls flash output by measuring how much flash reflects back through the lens (TTL) to the camera's built in lightmeter. It's usually the most accurate means of determining flash exposure, and it lets you aim your flash in any direction to bounce the light. It's accurate enough for most scenes and usually will function on many different cameras, while flash units that offer just TTL control work only with compatible cameras.

Dave Berry shares his Photography Tips at Computer School for Seniors (www.cs4seniors.com).

Capture the Moment Monday

Dave Berry, Director of the Photography Department at Computer School for Seniors will be sharing his insightful Photo Tips with you every Monday for Capture the Moment Mondays.

3 DSLR (Digital Single Lens Reflex)

 Questions you were afraid to ask--Part 3

1.) What's with "equivalent" focal lengths? Why do you sometimes call a 50mm a 75mm equivalent?
It refers to the corresponding focal length on a traditional 35mm film camera or full-frame DSLR. Because most DSLR sensors are much smaller than a 35mm frame film, they record on the center of the image circle cast by the full frame 50mm lens, producing images with the same field of view as those as those a 75mm lens would capture on a 35mm or full frame SLR.(The difference in area is called the crop or lens factor.

2.) Can my camera keep pace with the latest high speed memory card?
The newest model can, and manufacturers are always working on improving image transfer speeds and reducing the time it takes for ever larger image files to clear the camera's buffer. But another benefit of high speed cards is their ability to transfer images to your computer quickly. To make them run at top velocity, always use a compatible card reader.

3.) Does it harm flash cards to reformat them frequently?
Nope. In fact the experts encourage it. Reformatting scrubs images, file names and other image related data from the card, freeing up memory so you can keep shooting. It's best to reformat the card in the camera, rather than on your computer, to ensure they work together properly.

Dave Berry shares his Photography Tips at Computer School for Seniors (www.cs4seniors.com).