Mike Butler wants to know:
| This type of discussion always piques my interest. Previously we were
| discussing fill flash and some ideas (misconceptions really) I had
were
| cleared up. So now we are working on flash sync and I have some more
| ideas : ' ).
|
| 1. My OM 1n and 2s have curtain speeds of ~1/90 sec. If you have
a
| flash source that has a duration of (1/90 + Shutter speed + a fudge
| factor), the exposure would depend on the uniformity of the light
| output during that time. True or False
Seems false to me. It should depend on the total light output as the
curtain has to be wide open during the flash.
Above 1/60 sec the slit in the curtain begins to narrow although the
curtain remains at a constant speed, thus allowing less light to hit the
film. This is what gives the infamous black line on a flash photo that
was set > 1/60 sec. The flash duration is so short it ramains lit for
only part of the curtain travel time.
|
| 2. Is it possible to "String" a small number of flashes together
with
| a delay circuit between each to approximate the situation in item 1?
I
| have two A11's, they are fairly cheap and small, but it wouldn't be
| pretty.
This seems to be a very difficult task. Flash outputs are not exactly
the same, to begin with, so if you could time them to start exactly as
the last one went out, it would produce a photo with lighter and darker
bands. The output of a flash isn't just "on" or "off" but requires a
short period on each end of the flash where the output is less than
maximum. How would one overlap flashes and get the light consistant?
|
| 3. Earlier in this thread someone mentioned "modeling lights" as a
| solution. Does anyone know how long it takes a 12v Halogen Flood
light
| to come on to full power? Is it possible to use these as a flash bulb
| using the "FP" setting then turn them off automatically to conserve
the
| batteries. I am thinking of the type of lights I have on my bike and
| with reasonably small batteries they last for an hour or two. Maybe
| using smaller batteries and a "Flash" circuit the lights could yield
| acceptable results. Filters may / will be needed to balance the
color.
|
Halogen or tungsten light output and temperature changes as the unit
warms up. Results from shot to shot would be inconsistant if the lights
were turned on and off repeatedly. Longevity is more a function of the
on/off cycles that anything else as well.
| 4. Basically same as above but using Camcorder Auxiliary lights.
Basically same as above.
|
| 5. Back up lights from my SUV ( getting this thread back to the
| obligatory SUV content)
Same as above but bigger. :-)
|
| Thanks for the education,
Now we will see if an electrical engineer or one who understands
electronics agrees!
Gregg
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