I'm sure no one would develop a wobble on their flash if they never
let their camera hang lens down with the flash mounted - all the
force would be straight up and down through the mounting point.
When you hang it sideways, you've now got a pound of static torque
(I'm not an engineer... maybe it's not called static torque) but
basic physics, gravity sucks and it's sucking the pound of flash
perpendicular to the mount, which creates a twisting force. (Stick
your feet into a solid brace and try to hang parallel to the ground
and you'll experience it personally as your ankles snap.) Now walk
around with it (bounce, bounce, bounce) and now you're shaking the
joint between the flash and the camera with each step, probably two
or three pounds of torque forces. Ooops, bumped the wall
accidentally, take THAT hotshoe. (I did one of my D100 from solid
to jiggle once with one solid wall hit.)
Measure those two little strips on the top of the hotshoe,
calculate the area. That's the area of surface holding over a
pound in place.
I'm sure Nikon could reinforce the daylights out of the hotshoe,
but it wouldn't matter much unless you made the bottom of the
mounting point on the flash a lot bigger, to spread the load; made
the flash a lot stiffer and braced it to spread its weight over the
larger space; and then braced the camera and reinforced the hot
shoe to spread the weight. I don't want that camera.
If you never let the flash dangle off the top of the camera, it's
probably a non issue, or if you use a flash that was designed when
the hotshoe was designed (I've got a few of those cute little
buggers for my old fixed lens rangefinder cameras) it'd be a non
issue.
Flash brackets attach not to two thin metal strips on the top of
the hotshoe, but to the tripod socket on the bottom of your camera.
That socket is designed to take a lot of torque, relatively
speaking. Good flash brackets also make contact with the bottom of
your camera for at least a two inch square area, spreading the
stress over a large area. I have one that actually runs the width
of the camera, and it feels a lot more secure and balanced and
manouverable than the one that has a two inch square connection
pad. The weight of your flash will stress the metal on the
bracket, not your camera, and not that tiny little hot shoe.
I think it would also be useful to think about this: If you get a
big force at an angle against the flash, do you want it to break
the foot of the flash, rip the hotshoe off the camera, or take the
prism off... I'll bet somebody calculated how weak to make the
attachment points of the hot shoe to the camera body so that you
don't rip the top off the camera. And how weak to make the foot on
the flash. Breakaway! Which will wobble if subjected to enough
sub-breakaway forces enough times.
I'm definitely not saying hot shoes on Nikons with big heavy
flashes isn't a bad design. It most certainly is, but it's a bad
design on all cameras, and really should be treated as a
seldom-used stress point. If you make a living shooting weddings,
you're definitely asking way more from a hot shoe than you probably
should - and getting awful lighting compared to what you would with
the flash off camera, besides.
Being new to photography, only active for about 6 years, this
explanation never occurred to me. It's the first alternative to
Nikon bashing I've read. I attributed my problems similar to those
described in this thread, to an inherently defective mounting
design. That may have been half correct, but not forthe reasons I
was imagining.
But I do have a question. I have looked at flash brackets. It
appears to me that the are just a hot shoe on a post. What is
different about that in terms of problems of the fash unit
"wobbling?" It is still heavy piece of hardware connected to "less
than an inch" of holding bracket and connectors. Am I mising
something about the advantage to a bracket? Isn't there a need to
design a better clamping system to keep the contacts firmly in
touch with one another as the connecting hardware wears with use?
I want to know.
Keith
