Archived posting to the Leica Users Group, 2003/04/17

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Subject: Re: [Leica] forward into the past (bulb sync)
From: Rei Shinozuka <shino@panix.com>
Date: Thu, 17 Apr 2003 09:42:14 -0400
References: <20030417111145.GA3916@panix.com> <CD135E94-70D5-11D7-9460-0050E42E6E0B@shaw.ca>

so for example, if given a speed of 1/200 that covered 1/4 of the frame at
any given time, your HSS flash would emit 4 flashes that illuminated the 
subject as the shutter uncovered each quarter of the frame?

i am certainly no expert, but intuitively, that seems difficult to do without,
as you say, gaps or overlaps.  the smallest deviation in tolerance would be
visible in the frame.  i had assumed a flash system capable of short multiple
flashes and a high degree of persistence (like a TV tube) so as to 
approximate a continuous flash.  

but you learn something new every day, don't you? :-)

- -rei


On Thu, Apr 17, 2003 at 07:09:20AM -0600, John Collier wrote:
> No, HSS flash is not like  the M sync on the earlier cameras. HSS 
> carefully syncs a series of low power flashes with the shutter as the 
> slit crosses the film plane. It has to be precise as there can be no 
> gaps (dark  bands) or overlap (bright bands) in the multiple flash 
> exposures.
> 
> John Collier
> 
> On Thursday, April 17, 2003, at 05:11 AM, Rei Shinozuka wrote:
> 
> >it occurred to me upon acquiring an M3, that the idea behind the M sync
> >was that it triggers when the first curtain starts to open as opposed 
> >to X
> >sync which is triggered when the first curtain is completely open and 
> >before
> >the second starts to close.  this permits the (relatively) long-burning
> >flashbulb to provide illumination as the slit is traversing the frame.
> >
> >isn't that exactly the idea behind the new high-sync electronic 
> >flashes; to
> >provide quasi-continuous output for an interval of 1/50th second, and
> >therefore would one be compatible with M-sync machines (like the M3?)
> 
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- -- 
Rei Shinozuka shino@panix.com
Ridgewood, New Jersey

- --
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Replies: Reply from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] forward into the past (bulb sync))
In reply to: Message from Rei Shinozuka <shino@panix.com> ([Leica] forward into the past (bulb sync))
Message from John Collier <jbcollier@shaw.ca> (Re: [Leica] forward into the past (bulb sync))