The chart lists approximate guide numbers for manual flash calculations. The following equations are useful in determining the guide number, aperture (ƒn), or flash-to-subject distance required for expo- sure.

Guide no. (for distance in meters / feet)

Manual

Camera sensitivity (ISO)

 

flash

100

200

400

800

1/1 (Full)

8 / 26

11 / 36

16 / 52

22 / 72

1/2

5.6 / 18

8 / 26

11 / 36

16 / 52

1/4

4 / 13

5.6 / 18

8 / 26

11 / 36

1/8

2.8 / 9.2

4 / 13

5.6 / 18

8 / 26

1/16

2 / 6.6

2.8 / 9.2

4 / 13

5.6 / 18

Guide no. = distance ƒn.

Guide no. = ƒn. X distance

Guide no. = ƒn. distance

Flash Notes

Maxxum/Program Flash 2500(D), 3600HS(D), 5600HS(D), Macro Ring Flash 1200, and Macro Twin Flash 2400 are compatible with this camera. ADI flash metering works with the three Maxxum/Program flashes attached to the accessory shoe. See the flash manual on how to set ADI metering. The use of other flash units is not recommended.

With the Maxxum/Program Flash 5600HS(D) and 3600HS(D), the flash-metering mode will automatically switch to pre-flash TTL when the bounce-flash or wireless/remote function is used, or the flashes are connected to the camera with an off-camera cable. Pre-flash TTL auto- matically activates when using the macro flash units. When using bounce flash with the Maxxum/Program Flash 2500(D), set TTL with the metering mode switch on the flash unit or pre-flash TTL on the recording menu on the camera.

When using the Maxxum/Program flash units, if the flash illumination is uneven at the camera’s wide-angle lens position, attach the wide-angle adapter to the flash units. With the 3600HS(D), also change the flash metering mode to pre-flash TTL. When the auto-zoom function is used with the Maxxum/Program 3600HS(D) and 5600HS(D) flash units, the flash’s zoom setting will be wider than the lens setting.

When using the Macro Ring Flash 1200 or Macro Twin Flash 2400 in macro mode (p. 49), light fall off toward the edges of the frame may be noticeable at the wide-angle macro lens position.

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Minolta A1 instruction manual Flash Notes