Bowens guide numbers

[adam_mueller]

<p>Hi all,</p>

<p>I have 2x 500W heads which I purchased for a youth club and would like to know if Bowen's provide guide numbers for their studio lights? I am a Canon user.</p>

<p>Thank you :)</p>

[Charles_Webster]

<p>Because studio strobes often have interchangable modifiers the guide number isn't specified because it's modifier-specific.</p>

<p>You are better off using a flash meter or the camera histogram to calculate your exposures.</p>

<p><Chas><br /><br /></p>

[Alan Marcus]

<p>You can calculate an accurate guide number valid for your circumstances. It’s easy! Place your typical subject 10 feet from your flash unit. Shoot a series setting your camera at each aperture (f/number) setting. I advise having the subject display a placard indicating the f/number used. Evaluate the series for best results. Now multiply the f/number used by the lamp-to-subject distance. Example: Best of the series exposed at f/16 – multiply 16 x 10 = 160 (the guide number). Metric users, place the subject at the 4 meter mark – best was f/11 thus the metric guide number is 11 x 4 = 44.</p>

<p>To use, measure or estimate subject-to-lamp distance and divide into guide number. Example – guide number is 200 and the subject is 12 feet from the lamp. 200 ÷ 12 = 16.6. Use f/16 for your aperture setting.</p>