[Leica] Flash with Leica! Sacrilege!

[pklein at 2alpha.net (Peter Klein)]

OK folks, I know this is not exactly the Leica Way, and I'm as much of an 
available light guy as anybody here.  But sometimes you just gotta get the 
@#$%ing picture.

I shot a friend's wedding, PJ-style, a week ago.  I used available light 
while it was available, and switched to bounce flash when it was not.  Once 
the sun went down and light wasn't coming into the skylights and windows, 
exposure would have been around 1/30 at f/1.4 at ISO 1600, with lots of 
shadows and variations.  As much as I love the 
grainy-film-noir-moody-motion-blurry look, it wasn't going to cut it there.

So there I was, shooting my M6TTL with my old Vivitar 2500 auto-thyristor 
NON-TTL flash, bouncing light off the ceiling, with the lens set to f/2.8 
as recommended by the flash calculator.  It worked fine most of the time, 
except that I sometimes wanted a vertical shot.  The flash has only a 
bounce head, not a bounce-swivel head, so I had to switch to direct flash 
(yeech) for those, bounce the light off the wall if they were close enough, 
or forgo the vertical shot.

So I got to thinking, maybe I ought to invest in a flash with a 
bounce-swivel head, so vertical shots would be more possible.  A used unit 
is certainly a possibility.  I'll need something with reasonably low 
trigger voltage, so I could use it on a digital camera and the M6TTL as 
well as an all-mechanical camera.  Any ideas?

Something weird:  When I was testing the Vivitar flash before the wedding, 
I put it on my Olympus E-1. I shot with all-manual exposure on the camera 
at 1/60 second--well within the flash exposure range of the camera, and 
auto-thyristor mode on the flash.  Yet my exposures varied widely with 
distances between 3 and 20 feet.  On BW400CN print film with the M6TTL, 
there was some variation, but always well within the range of the film, as 
it's always been.  I got the same variation of exposure on the E-1 with 
another (non-tilting) old flash I own.  I was shooting an outside wall of 
my gray house.

So I'm wondering if both flashes are working improperly, if the thyristors 
are calibrated for reasonable results with color print film latitude--not 
precise exposure, or if I generated some weirdness by putting an old 
two-contact auto-flash on a computerized E-1 digithingie.

--Peter