Jill Rahn's picture  Clamp It Regarding a reader’s query about
an umbrella clamp (February, 2011, column), Larson Enterprises (
has a universal clamp for their reflectors that I have used to
attach any number of items to each other. It is shown in the
accessories section of their website and currently runs $49.
George Kwain via e-mail  You are right. Larson has offered lots
of helpful light-modifying devices for several decades. I was
not aware of the Universal Clamp but it’s logical that they
would make some method of holding or clamping one of their
reflectors.  Power Ratio Q. I have two flashes with different
Guide Numbers (GN). One has a GN of 175 and another has a GN of
137. If these are both used as remote flashes in the same shot,
in TTL mode, is there anything I need to do to even out these
different powers? Robert Laird Lafayette, IN  A. You mention
shooting TTL, but don’t say whether you are using wireless TTL
metering for the flash. But here’s the gist of the situation
when using two different outp