The Specs

Additional Specifications
Autofocus Assist AF Assist Beam
Flash Range 26.20 ft
normalized-Weight 13.40
Frequency Band Wireless Flash:Control system: Optical pulse transmissionWireless position: Master (M), control (C), slave (S)Channels: 1 through 4Compatible modes: P-TTL, auto (A), manual (M)Effective range: Approx. 13ft (according to Pentax testing conditions)
Maximum Flash Recycle Time 6 Second
Flash Synchronization 1/1200 to 1/20000
Battery Model Supported FR6
Brand Name Pentax
Minimum Synchronization Shutter Speed 1/1200
Light Angle 98 Horizontal (Flash)
Mount Type Shoe Mount
Maximum Synchronization Shutter Speed 1/20000
Product Model AF540FGZ
Number of Batteries Support 16
General
Warranty Information 1 Year Limited
Dimensions 5.60" Height x 3 Width x 4.20" Depth
URL http://www.pentaximaging.com
Weight 13.40 oz - Without batteries
Quick Glance
Flash Mode P-TTL|TTL|Automatic|Manual
Performance
Flash Recycle Time 6 Second Approximate - Alkaline|6 Second Approximate - Nickel hydroxide (Ni-MH)|6 Second Approximate - Lithium
Battery Life 200 Flash Approximate - Alkaline|250 Flash Approximate - Nickel hydroxide (Ni-MH)|350 Flash Approximate - Lithium
Flash Coverage 20 mm to 85 mm
Guide Number 45 m/148 ft at ISO 100 (50 mm Zoom-head Setting)|54 m/177 ft at ISO 100 (85 mm Zoom-head Setting)

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