Wednesday, November 16, 2011

Gear Day- Pop Goes the...

Greetings, Hohenfels, welcome to Hohenfels Volks, THE place for our place and our Volks. Another day, trees covered in white and ready for the icy grip of winter, closes around us.

Today we’re going to talk about flash. Learning to use flash is one of the major steps you should take in getting your photos gallery ready.

Today’s electronic flashes work amazingly well and can put a great deal of light right where you need it. The secret to using flash to get the right exposure is knowing how to meter and knowing how to balance your lighting.

First, let’s talk about several terms and features of an average flash.

The first term to know is Guide Number or GN. This is an indication of your flash’s power. It means your flash can provide light up to that distance at maximum zoom, for ISO 100. It’s usually measured in meters. The Canon 580EXII has a guide number of 58, as does the Yongnuo YN-560. This is used to calculate manual flash settings for your camera.

The second term is zoom. Your flash can often zoom to a preset distance to match the zoom of your lens, allowing it to throw light more in line with what you are shooting. This is extremely useful in auto flash; the drawback to that is the camera must be connected to the flash. The longer the zoon, the further the light will travel, and the less it will spread out.

The third term is sync speed, or shutter sync speed. On most higher end cameras, like the EOS 7D and 60D this is 1/250. For the lower end cameras, like the Digital Rebel series, this is 1/200. Some cameras won’t sync above 1/125 to 1/160. The slower the maximum sync speed, the slower you have to shoot. At speeds above the sync speed, either you will need a flash with high-speed sync, or you will get dark bands on your image.

The fourth term is rear or front curtain sync. In rear curtain sync, your flash fires at the end of the exposure, and in front curtain it fires at the start. This really only applies beginning at 1/30 – 1/60, depending on your model.

The last term I’ll introduce is TTL. Most of today’s automatic flashes are capable of being controlled by the camera, provided they are mounted to the camera. Today’s cameras meter through the lens, and pass that information to the flash to set output power and zoom. Many cameras use a more advanced feature called E-TTL, which is electronic metering through the lens. Using this method can improve your flash exposures. The downside is using your flash on camera can be disappointing, as it flattens the light and removes depth and character.

The range of a flash is limited by inverse square law, which states that light drops off from a source rapidly. For instance, a flashlight shined into the dark starts out quite bright, but ends up not even visible beyond some distance based on its power. This law states that doubling the distance from a subject to a source reduces light to ¼ its original level. Almost all light sources follow this rule.

When using your flash on camera, use your E-TTL features to get the best exposure. To correctly expose flash manually, you will need to adjust your aperture to control exposure for the light from the flash and your speed to control ambient light. To find the required to take a photo of a subject use this formula- f-stop number = GN/distance to subject. To figure out the distance to place your flash for a preset aperture use this formula- distance = GN/f-stop number. These are usually measured in meters, so remember to set up accordingly. Guide number is at ISO 100, so any change in ISO, must be accounted for.

A couple points- on camera flash gives a hard light, which results in a loss of shadows in the image making the subject appear flattish. On camera, or flash on the axis of the lens, gives red-eye effect, which is when the eye reflects red light straight back in the direction it came from.

Another thing to mention about off camera flash, besides adding depth, character, and bringing out detail, when used properly it can bring out the eye colors and make them stand out a little. This is especially true in brown and dark eyes. It takes some practice, but the results are worth it!

I like to use the YN-560, as this a nice, inexpensive, and powerful manual flash, paired with my with radio triggers. This allows for shots on camera can’t get, and it creates a nice direction to the light. Having directional lighting on a portrait really adds to the magic. That’s why you see it even in the paintings from the old masters. Next time we talk about flash, we’ll discuss fill, main, and lighting ratios. We’ll also discuss basic lighting patterns for portraits, and how to take the guesswork and mathematics out of getting your manual flash exposures.

I hope this information brings you another tool in our quest for the perfect picture. Let me know if it has! Remember to share your pics and post your questions at the Hohenfels Volks Facebook page, and or by commenting here!

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