Longest duration t=0.5 value flash units [REVISED]: 1. Metz Mecablitz series: Full-power = 1/250th* 2. Quantum Qflash: Full-power = 1/300th 3. Calumet Travelite 750R: Full-power = 1/650th†† 4. Dynalite Uni400JR: Full-power = 1/675th 5. Speedotron Force 10: Full-power = 1/850th [constant at all power levels] 6. Bowens Gemini Classic 500C: Full-power = 1/900th 7. Elinchrom Quadra-S: Full-power = 1/1,200th ['A' outlet] *The t=0.5 specification for the Metz units is unconfirmed. While Metz' published t=0.1 specification is 1/125th at full power, Metz' does not publish a t=0.5 specification. See sources below for more information: http://pttl.mattdm.org/timing:flash-duration:metz http://speedlights.net/2010/11/10/metz-48-af-1-flash-review/ ††The Calumet Travelite 750 t=0.5 specifications can be seen here on the Calumet site: http://www.calumetphoto.com/eng/product/calumet_travelite_750r_radio_enabled_monolight/ce1106 Though both the Calumet Travelite 750 and Bowens 750 appear to be similar products, the Bowens 750 Pro has a published t=0.5 value of 1/2,300th: http://www.bowensdirect.com/index.php/compact-flash/geminipro/gemini-750pro.html However, the published Bowens figure raises another question. Even though the Bowens site states that the t=0.5 flash duration is 1/2,300th, based on this product description, "The Gemini 750Pro monolight feature all of the benefits of the Gemini r units, including Travelpak battery and Pulsar Trigger Card compatibility, but also offers more power and flash-durations as fast as 1/2300 sec. [emphasis added]," implying that a slower duration exists.