GUIDE NUMBER ---------------

See the table below for guide numbers.

Guide number at flash-to-subject distance of 1m (approx. 3.3ft.)

Amount of light output

 

 

 

ISO film speed

 

in M mode

25

50

100

200

400

800

For both flash modules

6.5

9

13

18

26

36

with controller batteries

(21)

(30)

(43)

(60)

(85)

(120)

Full

 

 

 

 

 

 

For only one flash

7.5

11

15

21

30

42

module or with external

(25)

(35)

(49)

(69)

(98)

(139)

power source·

 

 

 

 

 

 

1/4

3.2

4.6

6.5

9

13

18

(10)

(15)

(21)

(30)

(43)

(60)

 

1/16

1.6

2.3

3.2

4.6

6.5

9

(53)

(7 .5)

(10)

(15)

(21)

(30)

 

Unit: m(ft.)

1000 1600

41 52

(135)(171)

48 60

(156)(197)

21 26

(68)(85)

10 13

(34)(43)

•For external power source with only one flash module, see the figure indicated in the column to the right (column for one step higher film speed)

In TTL auto flash operation, for usable apertures with a reproduction ratio lower than 1: 10, use the following equation:

 

guide number at

guide number at

Usable

full output

1/16 output

lis tops -

flash-to-subject

flash-to-subject

 

distance

distance

In manual flash operation, for usable aperture with a reproduction ratio lower than 1:10, use the following equation:

guide number

Usable flstop = -- = ---------

flash-to-subject distance

READY-LIGHT INDICATIONS -----------

When the controller AS-12 or AS-14 is turned on, the controller ready-light comes on to indicate flash is ready to fire.

To activate the viewfinder ready-light function when us- ing the Nikon F4-series, F-801 /N8008, FA, FE2, F-501/N2020, F-301/N2000, FG or FG-20, turn on the

camera meter by lightly pressing the shutter release button.

With alkaline-manganese or zinc-carbon batteries, if the ready-light takes more than 30 sec. to light up, replace batteries with a fresh set.

Ready-Light Warning Functions

To prevent errors listed below, the ready-lights inside the camera's viewfinder and on the controller blink, after the S8-21 is turned on.

With SB-21A

Blinking ready-light

Inside

viewfinder On AS·12

00

0-

Problem and remedy

1)The AS-12'smounting foot is not securely locked. Firmly tighten lock ring .

2)The AS-12 is set at TTL with a camera other than a Nikon F3-series camera. Reset flash mode selector to M.

3)In TTL mode, the film speed setting on the camera is beyond the usable range . Use film within range of ISO 25 to 400 .

4)The flash fired at full light output in TTL mode ; lighting might be insufficient. (See page 37).

The shutter speed set on the FM2 or FE is faster than the flash sync speed. Reset to flash sync speed or slower.

40

Page 39 Page 41
Page 40
Image 40
Nikon Guide number at flash-to-subject distance of 1m approx .3ft, Ready-Light Warning Functions, With SB-21A
Page 39 Page 41

SB-21 specifications

The Nikon SB-21 is a highly regarded external flash unit that has earned a reputation among photographers for its versatility and reliable performance. Designed for use with Nikon’s line of DSLR cameras, this compact flash unit is favored by both amateur and professional photographers alike.

One of the key features of the SB-21 is its powerful guide number, which provides robust illumination in various settings. This allows users to effectively light subjects even in challenging low-light environments or larger spaces where additional lighting is essential. The SB-21 also boasts a range of customizable settings, giving photographers control over the intensity and direction of light.

The flash offers a zoom head, which allows it to cover various focal lengths. This adaptability is particularly beneficial for photographers who frequently switch between wide-angle and telephoto lenses. The ability to zoom not only enhances light coverage but also ensures that the flash can be fine-tuned to match the specific needs of each shot.

In terms of technology, the SB-21 integrates Nikon’s advanced i-TTL metering system. This intelligent system measures the light needed for a scene and adjusts the flash output accordingly, resulting in well-exposed images with minimal user intervention. This feature enables photographers to focus on their composition without worrying about manual exposure settings.

The build quality of the SB-21 is another highlight, as it is designed to withstand the rigors of regular use. It features a durable exterior that enhances its longevity, making it a trustworthy tool for outdoor and event photography. Additionally, the flash unit supports wireless operation, enabling users to trigger it remotely for creative lighting setups.

The Nikon SB-21 also includes a variety of accessories, such as diffusion panels and bounce cards, allowing further customization of light output to achieve specific effects.

Overall, the Nikon SB-21 stands out as a reliable and feature-rich external flash unit that meets the demands of various photographic styles. Its versatility, intelligent technology, and robust construction make it an essential accessory for any Nikon photographer looking to enhance their lighting capabilities. Whether shooting portraits, events, or creative projects, the SB-21 delivers exceptional performance and quality, making it easier to capture stunning images in any lighting condition.
Top Page Image Contents