Newly designed circuitry and light-emitting unit produces powerful guide number of 33. In addition, a high precision aspherical optical troidal lens has been fitted over the two flash tubes to disperse an even light from the center to the edge. The strobe`s beam angle will increase to 110°by attaching the standard accessories Diffuser. When the optional Dome diffuser is attached, beam angle will increase to as wide as 150(TBD)
In order to avoid misunderstanding, the YS-D3 guide number (GN) and the beam angle are based on measurements taken on land (not underwater)
Some competitors will often state a GN measured on land and the beam angle in water, for example a GN 33 and beam angle of 110 degrees. However, this GN 33 value is based on a beam angle of 60~70 degrees. The beam angle may be expanded in water by a dome effect, however the GN in water is significantly lower than the value measured on land.
Note: A land-based strobe that uses the same four AA batteries as the YS-D3 may provide a notation that the GN is 60, but these measurements are taken under the condition that the focal length is equivalent to 200 mm (= beam angle 12 °). When the beam angle becomes narrower, the brightness of the illuminated area increases due to the light-collecting effect.