Normal Power

The narrow beam guide numbers are interesting, but they're only relevant at higher focal lengths. This list represents the middle of the zoom range — a field of view which covers the "normal lens" range of 50mm equivalent focal length — that is, about 35mm on a current Pentax dSLR. If a flash only has a zoom setting wider than this field of view, this table shows the power with the most focused beam available.

chart?chtt=Relative+Flash+Power+at+50mm+EFL&chs=640x22&chbh=22&cht=lc:ndaK-5+Built-In,404040,0,1,12,0chart?chs=640x82&chbh=22&cht=bhs&chg=7.6923,0,1,2&chds=0,2.4&chd=t:0,0,0|0.44,1,2.25&chm=tPentax+AF200FG,404040,0,0,12,0|tPentax+AF360FGZ,404040,0,1,12,0|tPentax+AF540FGZ,404040,0,2,12,0+AF-2,404040,0,7,12,0chart?chs=640x56&chbh=22&cht=bhs&chg=7.6923,0,1,2&chds=0,2.4&chd=t:0,0|1.78,2.35&chm=tSigma+EF-530+DG+%28ST+and+Super%29,404040,0,0,12,0|tSigma+EF-610+DG+%28ST+and+Super%29,404040,0,1,12,0chart?chs=640x160&chbh=22&cht=bhs&chg=7.6923,0,1,2&chds=0,2.4&chd=t:0,0,0,0,0,0|0.64,1,1.44,1,1,1.28&chm=tPromaster+5250DX,404040,0,0,12,0|tPromaster+5550DX,404040,0,1,12,0|tPromaster+5750DX,404040,0,2,12,0|tPromaster+7200EDF,404040,0,3,12,0|tPromaster+7400EDF,404040,0,4,12,0|tPromaster+7500EDF,404040,0,5,12,0chart?chs=640x82&chbh=22&cht=bhs&chg=7.6923,0,1,2&chds=0,2.4&chd=t:0,0,0|0.54,1.87,2.05&chm=tTumax+DSL28AF,404040,0,0,12,0|tTumax+DPT3AFZ,404040,0,1,12,0|tTumax+DPT5AFZ,404040,0,2,12,0
  • Sigma EF-610 DG = 2.4×
  • Pentax AF540FGZ = 2.2×
  • Tumax DPT5 = 2.1×
  • Metz 58 AF-1/AF-2 = 2.0×
  • Tumax DPT3 = 1.9×
  • Metz 54 MZ-4i = 1.8×
  • Sigma EF-530 DG = 1.8×
  • Metz 52 AF-1 = 1.6×
  • Promaster 5750 = 1.4×
  • Metz 50 AF-1 = 1.4×
  • Metz 48 AF-1 = 1.4×
  • Promaster 7500EDF = 1.3×
  • Metz 44 AF-1 = 1.1×
  • Pentax AF360FGZ = 1.0× (Of course.)
  • Promaster 7400EDF = 1.0×
  • Promaster 7200EDF = 1.0×
  • Promaster 5550DX = 1.0×
  • Promaster 5250DX = 0.64×
  • Metz 36 AF-4/AF-5 = 0.64×
  • Metz 24 AF-1 = 0.64×
  • Tumax DSL28 = 0.54×
  • Pentax AF200FG = 0.44×
  • K20D/K200D/K-7/K-5 built-in = 0.19×
  • K100D/K10D/K2000/K-m/K-x/K-r built-in = 0.13×
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