Archived posting to the Leica Users Group, 1999/06/01

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Subject: Re: [Leica] Studio Flash Photography with M6 TTL
From: csocolow <csocolow@microserve.net>
Date: Tue, 01 Jun 1999 23:52:13 -0400

The Adler Family wrote:
> 
> Dear LUGers,
> 
> I have recently bought a M6 TTL, Summicron 35 and Elmarit 90, all new. As
> this was a *somewhat* impulsive purchase, I must now sell my Nikon and
> Contax systems. The Contax sale poses no problem, but I do use the Nikon
> system to generate some income from portrait studio work. I use 3 Nikon
> flashes with umbrellas and backdrop for this paying work.
> 
> My dilema is this; I would like to continue to do an occasional portrait
> shoot using my Nikon flashes in conjunction with the M6. I use a Sekonic
> meter to measure incident flash and then manually adjust flash output. The
> Sekonic measures incident light from the flashes either at 1/30sec or
> 1/60sec shutter speed. I consider 1/30sec too slow for portraits (people
> tend to blink, twitch, not to mention my espresso shakes) and the M6 has a
> synch speed of 1/50 (frankly, I think this is a rather unusual synch speed,
> but that's another thread). The Sekonic meter will show me incident light in
> increments of 1/10 of a stop (e.g., f8, f8 & 1/10, f8 &2/10).
> 
> My theory as to how to adjust flash output using the Sekonic to correlate to
> the 1/50 synch speed of the M6 is as follows. Let's take this example: I
> want to take the shot at 1/50 f4. Because 1/50 is 1.2 times the amount of
> exposure achieved with 1/60, I want the Sekonic to show, at a speed of 1/60,
> an f-stop that is 0.2 times wider open than the f-stop of the camera: that
> would be f2.8 + 8/10 stop. Assuming that the 1/10 stop indicators on the
> Sekonic represent increments of light flow (not diameter), is my theory
> correct?
> 
> Of course, I'll be shooting some rolls to test this out, but I thought I'd
> run it past the experts to see if I was making a material blunder.
> 
> Thanks in advance for any help you can give.
> 
> Bob Adler

Bob,

Shutter speed has nothing to do with flash exposure unless you have gobs
of ambient that exceed flash exposure. Particularly in a somewhat
controlled studio-type scenario 1/50 or 1/60 or 1/30 shouldn't make a
difference. Even 1/30 your exposure will be frozen by flash unless
subjects are really hopping around enough for the ambient to register. I
use strobes with modelling lights and they don't even contribute that
much. Just take the meter reading and go with it. 
- -- 
Carl Socolow

http://members.tripod.com/SocPhoto/