Archived posting to the Leica Users Group, 2002/01/13

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Subject: [Leica] Re: NEW M7 MAJOR CROCK-POT CROW PARMESAN
From: Jim Brick <jim@brick.org>
Date: Sun, 13 Jan 2002 19:24:47 -0800
References: <200201132018.MAA12053@mejac.palo-alto.ca.us>

At 09:35 PM 1/13/2002 -0500, Rolfe Tessem wrote:

>While you might use the TTL flash metering capability of the M6 TTL 
>occasionally, as I do, no professional in his/her right mind would use it 
>on on a real job that really required this capability for the successful 
>completion of the assignment. You'd be too worried that that the 1/50th 
>sync speed just wouldn't let you get the shot.



The funny thing is, the 1/50th is only a problem for flash fill when 
photographing outdoors.

When the flash is the main light (indoors), the 1/50th sync speed is of 
little consequence. Electronic flash's minimum speed is around 1/800th sec, 
for big studio flashes, and all the way up to at least 1/20,000th sec for 
small on camera flashes.

They were used in the early days as "strobes" (hence the name) and people 
produced photographs of an apple exploding via a bullet. The flash froze 
the bullet as well. Or stroboscopic photos of a golf swing...

Flash speed is based upon the farad capacity of the flash capacitor and the 
resistance of the flash tube circuit. Ohms law. Basically, a very large 
capacitor (big watt seconds - lots of light) gives a longer slower brighter 
flash. Small capacitors will give very high speed (but low power) flash. To 
get high speed and high power, one must use low resistance flash tubes and 
circuits and monster cable to get the electrons to the tube in a real 
hurry. Hardly what one would expect in an M camera twinky light.

I think my Metz 60CT-4 goes from about 1/800th to 1/25,000th as I can dial 
the power from full power to 1/32 of full power (two clicks past 1/16.)

I know numerous professional photographers that use their M6 cameras, with 
flash, on real jobs.

Jim


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