Using the Built-in Flash

Distance and Aperture when Using the Built-in Flash

A set criteria is necessary between the guide number, aperture and distance when shooting with the flash. Calculate and adjust the shooting conditions if flash is not sufficient.

Built-in flash guide number

Sensitivity

Built-in flash guide number

ISO 100

13

ISO 200

18.4

ISO 400

26

ISO 800

36.7

ISO 1600

52

Calculating Aperture Value from Shooting Distance

The following equation calculates the aperture value for shooting distances.

Aperture Value Used F = Guide number ÷ Shooting distance

Example)

When sensitivity is [ISO 200] and shooting distance is 6.1 m, aperture value is: F = 18.4 ÷ 6.1 = 3

If the resulting number (3, in the above example) is not available as a lens aperture, the smaller number that is closest (2.8, in the above example) is generally used.

Calculating Shooting Distance from Aperture Value

The following equation calculates the distance of the flash for aperture values.

Maximum flash distance L1 = Guide number ÷ Selected aperture

Minimum flash distance L2 = Maximum flash distance L1 ÷ 5*

*The value 5 used in the formula above is a fixed value which applies only when using the built-in flash alone.

Example)

When sensitivity is [ISO 200] and aperture value is F4

L1 = 18.4 ÷ 4 = approx. 4.6 (m)

L2 = 4.6 ÷ 5 = approx. 0.9 (m)

Therefore, the flash can be used in a range of about 0.9 m to 4.6 m. The flash cannot be used when the distance is less than 0.8 m. When the flash is used at closer than

0.8m, it causes vignetting in the picture corners, light is distributed unevenly and the picture may be over-exposed.

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Samsung GX-20 Distance and Aperture when Using the Built-in Flash, Calculating Aperture Value from Shooting Distance, 104

GX-20 specifications

The Samsung GX-20 is a notable digital single-lens reflex (DSLR) camera that debuted in 2007, capturing the interest of photography enthusiasts and professionals alike. As part of Samsung's foray into the DSLR market, the GX-20 offers a range of features and technologies designed to enhance the photography experience.

At the core of the GX-20 lies its 14.6-megapixel APS-C size CCD sensor, which provides high-resolution images with excellent detail and clarity. This sensor allows for a wide ISO range, from 100 to 6400, giving photographers the flexibility to capture images in various lighting conditions without sacrificing image quality.

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The camera's design is both ergonomic and sturdy, featuring a weather-sealed body that ensures durability when shooting in challenging weather conditions. The 2.7-inch LCD screen provides a clear view for composing shots and reviewing images, and it incorporates live view functionality, enabling users to shoot from different angles easily.

In terms of autofocus, the GX-20 is equipped with a 11-point autofocus system, which enhances focus accuracy and speed. Photographers can choose between multiple autofocus modes, including single-shot, continuous, and manual focus, providing flexibility for various shooting scenarios.

Additionally, the GX-20 supports a range of advanced shooting modes, including face detection, scene modes, and exposure bracketing, allowing users to easily adapt to different photography styles. The camera also incorporates an in-camera RAW processing feature, enabling photographers to edit their images without the need for external software.

Connectivity options on the GX-20 include USB 2.0 for data transfer and support for SD/SDHC memory cards for storage. With an average battery life of approximately 600 shots, users can confidently shoot without the constant worry of running out of power.

Overall, the Samsung GX-20 represents a solid choice for both amateur and seasoned photographers. With its blend of high-resolution imaging, robust performance, and thoughtful design, it offers an appealing package that stands the test of time in the ever-evolving world of digital photography.