Pentax AF540FGZ ■Guide Number (GN), ISO, 35mm, 85mm, 70mm, 50mm, 35mm, 28mm, 24mm, 70mm, 55mm, 45mm, 90mm, 70mm, 60mm, 58mm, 48mm, 34mm, 24mm, 19mm, 16mm, Flash, *20mm, light

■Guide Number (GN)

Guide numbers indicate flash light intensity. The larger the number, the farther you can reach with your flash. From the guide number, you can easily obtain the proper aperture setting required for an optimum exposure.

Aperture (f/stop) = GN/flash-to-subject distance (m)

●Depending on the camera and lens you are using, the effective flash range may be displayed. (Refer to page 81.)

Guide Number Table						*With the wide-angle panel attached
	Flash	Camera format			Zoom position
		35mm	85mm	70mm	50mm	35mm	28mm	24mm	*20mm
ISO	light	645	150mm	135mm	100mm	70mm	55mm	45mm	*35mm
	intensity	67	190mm	180mm	120mm	90mm	70mm	60mm	*55mm
		DIGITAL	58mm	48mm	34mm	24mm	19mm	16mm	*13mm
		1/1	54	50	45	39	35	32	21
		1/2	38	35	32	27.5	24.5	22.5	14.5
ISO100		1/4	27	24.5	22.5	19.5	17	16	10
		1/8	19	17	16	13.5	12	11	7
		1/16	13.5	12	11	9.5	8.5	7.5	5
		1/32	9.5	8.5	8	6.5	6	5	3.5
		1/64	6.7	6	5.6	4.6	4.2	3.5	2.4

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