Re: READ THIS ONE- Studio Photography

Why would reciprocity failure even be a problem? It occurs when there are
very long exposure times. I beleive even the slowest flashes on the market
are much faster than 1/1000 of a sec, so even if you flashed 100 times, it
would still be less than 1/10 of a sec, which is in the reciprocity range of
most films. Failure would not be a problem. If I am wrong, please correct
me, I've never tried it, this is just what 'popped' into my head.

John
----- Original Message -----
From: "Tom Ferguson" <tomf2468@pipeline.com>
To: <pinhole-discussion@pinhole.com>
Sent: Monday, November 20, 2000 5:14 PM
Subject: Re: [pinhole-discussion] READ THIS ONE- Studio Photography

> > From: Levi Brown <kerplop1@juno.com>
> > Subject: [pinhole-discussion] READ THIS ONE- Studio Photography
> >
> > Andrew,
> > I've been doing this for several years now... here is what you do.
> > First determine the effective aperture of your camera. For my 4x5 mine
> > is about F-256 and for my converted Hasselblad it is about F-140. Get
> > yourself a flash meter and get your strobes close to your subject.
> > Ideally if you can get your meter to read F-45 you are doing good. This
> > whole bit about doubling your number of flashes to add an extra stop is
> > nonsense. Everytime that you flash the strobes you add an extra stop of
> > light. Lets say that I set up my lights and get a meter reading of
F-45.
> > Lets count: F-45, F-60, F-90, F-128 That equals 4. So to get
> > sufficient exposure you need to pop your flash 4 times. Just to be on
> > the safe side do it 5 to add a little extra density and account for
> > reciprocity. It really is that simple. With my Hasselblad my exposure
> > times are about 4 pops of the flash and with my 4x5 they run around 9.
>
> I'm sorry, but as someone who uses multiple flash pops for both pinhole
and
> lens work, this is simply WRONG. F45 to F128 needs AT LEAST 8 times as
> many "pops". Lets count: F45 to F64 is one stop (X2), F64 to F90 is
another
> stop (2X2=4), F90 to F128 is another stop (4x2=8). I say "AT LEAST"
because
> reciprocity (on the other end of the spectrum from pinhole, flashes can be
> too short an exposure) can increase the number of "pops" needed.
>
> My best guess is that Levi is using Neg film, as surviving on it's
> wonderfully forgiving exposure latitude :-)
>
> Try this with E-6 slide film or polaroid, and you'll see the truth.
>
> >
> > Another trick, if you are shooting black and white, is to use Tmax 400
> > speed film. Tmax has significantly less reciprocity failure than other
> > black and white films. I've noticed that I get better negative density
> > with Tmax than with any other black and white film.
>
> Agreed! It is a nice film isn't it. The 100 speed T-Max is even better
for
> reciprocity.
>
> >SNIP>
>
> --
> Tom Ferguson
> http://www.ferguson-photo-design.com
>
>
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Received on Mon Nov 20 20:20:55 2000