Before I purchased my Metz 76 MZ5 about ten years ago, i was seriously thinking about a Quantum T5D-R. I had heard great things about this flash, but I opted for the Metz, because I thought they were a more stable company. We all know what happened to Metz. Both units sold for about $800-$900, but I think the Quantum was actually more expensive because you had to buy a heavy Power Pack and wire-less features so that the camera could communicate with the flash. The other day, someone was selling a Quantum T5D-R for about $50 so I jumped on it. I wasn't expecting much for $50, just wanted to get an idea how the flash worked before investing more money. I already owned a Quantum Power Pack (Turbo) so that would not be an issue. The seller even claimed that he had just changed the bulb(about $85) which made me even more suspicious. In any case the flash arrived in pretty good shape, with only a few scratches, which I quickly touched up with touch-up paint. For a bulky and awkward looking flash, it is actually pretty light, if you don't include the power pack. All the functions seemed to work TTL, Manual, Strobe, Auto. However, to get QTTL/ETTL you had to buy an adapter, or get the very expensive wire-less adapter kit. I opted for the regular adapter, but I really didn't want to go through the frustrating experience I had with the Metz trying to mach the right adapter to the camera. Without the adapter, I would need to find a Quantum Sync cable to attach to the camera and forget about QTTL. My curiosity got the best of me, so I purchased a Quantum "D-13n" adapter for about $25 on eBay. I wasn't sure if this was the right one, but I took a shot. When the adapter finally arrived, I quickly read the instruction manual and hooked it up to my camera(Canon 6D) and flash. That must have been the wrong adapter, because the camera did not communicate with the flash and the top LCD on my camera started acting erratically. The f-stop and time would switch back and forth and the ISO was boosted to 3200 on the flash unit even though the ISO on the camera read ISO=125 . I sent an email to the people at Quantum in Bartlet Illinois and was surprised that they got back to me the next day. The Rep at Quantum told me that D-13n adapter had not been updated since 2001. He said I should try the D23-n which was last manufactured in 2016 years after the Canon 6D came out. However, he said that still might not work because if I have a older version of the flash, then the Firmware would also need to be updated and they(Quantum) are the only ones who could do it. He showed me how to get to Firmware version and sure enough I had an older version. This $50 experiment is already turning into a night mare !! Quantum still sells the T5D-R brand new, but they also have a newer version called the TRIO with built in wireless ETTL functions. The TD5-R is more powerful though, coming in at a true 150W watts. The TRIO is about as powerful as a Canon 580 EX. They no longer make a regular adapter for the T5D-R, so you have to purchase the very expensive Wireless kit. This is what I hate about third-party flashes, you never know when you are going to get stuck in Limbo.