Ziv wrote:
A number of Einstein 640 users have had issues keeping large Octas and soft boxes attached to the light. I have been working on a solution and think I have found a simple, relatively in-expensive solution to keep our modifiers attached to our Einsteins. 
The Chimera QR speed ring does not fit the Einsteins properly. Other people who have used this speed ring have also experienced issues with large modifiers falling off (small light modifiers may be ok). In fact, any speed ring that doesn't allow the fingers to close properly could experience issues (see my other post on here regarding this). The picture from the "Wizard Bracket" that you link to shows the issue clearly. 
http://wizardbrackets.com/wp-content/up ... -14421.jpgFrom your picture you can clearly see that the fingers are only closed about 60% and not in the locked position. The Chimera QR speed ring has an opening that is too small (or flange too long) for the Einstein. I've discussed this issue with Chimera and hoping they will update their speed ring insert.
Once the fingers close 100% (or very close to it) and lock they will not open. It's hard to describe but if you have a chance to see the inside of a Balcar clamp the reason is very obvious. If the fingers are only closed 50% you are relying on the spring tension to hold up your large modifier and that will fail. As the fingers get closer and closer to 100% closure you are relying less and less on spring tension and more on two pieces of metal wedging to hold the fingers closed. When the fingers are closed 100% they are locked close by two flat metal surfaces pressing against each other.  Specifically, the flat surface of the finger is pressing against a flat part of a rotating ring inside the Einstein. The spring plays absolutely no part in holding up the modifier. The closure is rock solid and will not open. Again, if you see the way the part works it's very obvious that the fingers simply cannot open regardless of how large and heavy your modifier is.
Use a speed ring that closes 100% and you will have no issues with large modifiers. The Bowens Quick Ring with SP Systems insert works well. 
BTW, I'm not knocking the "Wizard Bracket" product at all. It looks good and might be a fine approach for mounting large modifiers. I'm just trying to add more info as to why folks may experience issues with large (heavy) modifiers falling off Einsteins and offer alternative solutions.