Portable lighting Question

[Marko]

Measuring how much light portable flashes output is tricky business. A given flash will output different amounts of watt seconds based on several variables including the angle of the light. It's almost like talking about liters or gallons of gas. How far will will you get on 1 liter? Depends on many variables like are you fueling a jet or a moped and how fast will that jet or moped travel and will they be driving on the highway or through city streets. You get my point.

For me, a more useful (but not foolproof) way to determine flash output is through guide numbers (GN). This measures direct flash output, at 10 feet, at ISO 100.

This comes from the alien bees site http://alienbees.com/specs.html

output measurements

B400 B800 B1600

Standard 7-inch Reflector

B400 f11 2/10

B800 f16 2/10

B1600 f22 2/10

11-inch Reflector

B400 f22

B800 f32

B1600 f45

48" Silver Bounce Umbrella

B400 f8 - f11

B800 f11 - f16

B1600 f16 - f22

48" Shoot-Thru Umbrella

B400 f5.6 - f8

B800 f8 - f11

B1600 f11 - f16

Medium Softbox

B400 f11– f16

B800 f16 – f22

B1600 f22 – f32

Based on your requirements the B400 'should' be plenty. BUT If I were making this purchase, I'd spend the extra 50 bucks and get the B800 just in case I ever needed a bit more power. You should know that the weight of the 800 is .4 pounds heavier which is not a big deal IMO. Ah what the heck - here's the chart.

weight/dimensions
weight

B400 2.5 pounds

B800 2.9 pounds

B1600 3.7 pounds

dimensions

B400 9” x 7.5” x 5.5”

B800 9” x 7.5” x 5.5”

B1600 9” x 7.5” x 5.5”

Here's a link to another one of company's flash explanations http://www.white-lightning.com/manuals/bluebook.htm

Hope that helps
Marko