Relative Flash Coverage

Flash Burst Profiles

While looking at power ratings numbers directly can be useful, another practical approach is to look at the total area each flash could cover at any zoom setting. That is, consider the flash to be fixed in one place and examine the possible places a single subject could stand and be appropriately lit. This takes into account both flash reflector zoom angles and the raw power needed to reach into the distance.

The following flash burst profile images use the actual correct angles for zoom settings. The shape and proportion of the profile remains the same regardless of aperture and ISO, but of course becomes smaller. And obviously light doesn't really work like this: the hard-edged cutoffs are a fiction — but a convenient one.








Relative Potential Flash Coverage

The flash burst profile concept can be boiled down to a single number by measuring the total potential area of flash coverage. The following list shows this area relative to that covered by the Pentax AF360FGZ. Since this incorporates all of the published numbers for each flash, the value is less susceptible to rounding errors or other unintentional inaccuracies than the other charts.

Keep in mind several things when looking at these numbers. First, the data is entirely based on manufacturer-stated numbers which may be faulty in multiple ways: the guide number could be overstated, and the angle of coverage at a given zoom position could be not completely adequate. Second, this particular number is not a measure of raw flash power. It's a partial indicator of the versatility which a certain amount of power can give you in combination with the zoom reflector of a particular flash.1

  • Sigma EF-610 DG = 2.6×
  • Pentax AF540FGZ = 2.3×
  • Metz 58 AF-1/AF-2 = 2.2×
  • Tumax DPT5AFZ = 2.1×
  • Metz 54 MZ-4i = 2.0×
  • Sigma EF-530 DG = 1.9×
  • Tumax DPT3AFZ = 1.8×
  • Metz 52 AF-1 = 1.8×
  • Metz 50 AF-1 = 1.6×
  • Metz 48 AF-1 = 1.5×
  • Promaster 7500EDF = 1.3×
  • Metz 44 AF-1 = 1.3×
  • Promaster 5750DX = 1.1×
  • Promaster 7400EDF = 1.0×
  • Pentax AF360FGZ = 1.0× (Of course.)
  • Metz 36 AF-4/AF-5 = 0.91×
  • Promaster 7200EDF = 0.87×
  • Promaster 5550DX = 0.87×
  • Promaster 5250DX = 0.56×
  • Metz 24 AF-1 = 0.44×
  • Pentax AF200FG = 0.39×
  • Tumax DSL28AF = 0.37×
  • K20D/K200D/K-7 built-in = 0.16×
  • K100D/K10D/K2000 built-in = 0.12×

If you need more power than this in a single flash, the non-hot-shoe mount Metz flashes which can use the Pentax P-TTL SCA module come in at 1.6× for the 45 CL-4 (with a much higher guide number at 35mm than any of the above), and an impressive 3.9× for the 76 MZ-5.

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