[rollei_list] Re: Flashbulbs
- From: John Jensen <jwjensen356@xxxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Tue, 31 May 2005 16:02:55 -0700 (PDT)
To clarify the designations of F and SM, I went to the
flashbulb site I spotted a couple of days ago:
"Type SM "Class F". - These GE Speed Midget Class F
(fast peak) flash bulbs were designed for use with
focal plane shutters, usually at 1/60 second shutter
speed and stopped action like a strobe flash. Bayonet
Base. These bulbs reached their peak of use during the
early 1960s. Gas filled. "
It looks like the purpose of the SM bulbs is to
provide quick action with focal plane shutters at the
slow speed when the curtain is entirely open. I
presume the FP bulbs have the long duration for use
with the focal plane shutter at hegher shutter speeds.
John
--- Jerry Lehrer <jerryleh@xxxxxxxxxxx> wrote:
> John,
>
> The F setting was used for SM bulbs.
>
> jerry
>
> John Jensen wrote:
>
> > My vague recollection is that M is 15-20
> milliseconds
> > delay, F about 5 milliseconds, and X zero
> > milliseconds.
> >
> > The purpose of the F bulbs was for a short
> lighting
> > time for action shots (not as quick as an
> electronic
> > flash, however).
> >
> > John
> >
> > --- Don Williams <dwilli10@xxxxxxxxxx> wrote:
> > > At 12:16 PM 5/31/2005, Richard wrote:
> > > > The GE No.50 and Sylvania No.3 were meant to
> be
> > > used in
> > > >studio reflectors with very slow shutter speeds
> > > (1/25th or
> > > >longer) or open flash. A single bulb in a 12"
> > > reflector has
> > > >a guide number of 600 for ISO-100 film. Thats
> f/6
> > > at 100
> > > >feet folks, try that with your stobe units.
> > > Remember, these
> > > >are bulbs about the size of 150 Watt household
> > > lamp.
> > > Was that the purpose of the "M" flash setting.
> I
> > > had cameras which had "F"
> > > and "M" flash settings.
> > >
> > > It seems to me that the "F" wasn't related to
> focal
> > > plane shutters but I'm
> > > not sure. I think it was another flashbulb
> setting.
> > >
> > > I had to grind a new cam to change the "F"
> setting
> > > on an old Argus to make
> > > it "X", which was for strobes.
> > >
> > > Anyone have any recollection about this?
> > >
> > >
> > >
> > > Don Williams
> > > La Jolla, CA
> > >
> > >
> > >
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