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" <tomf2...@pipeline.com> To: <pinhole-discussion@p at ???????> Sent: Monday, November 20, 2000 5:14 PM Subject: Re: [pinhole-discussion] READ THIS ONE- Studio Photography > > From: Levi Brown <kerpl...@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 > > > _______________________________________________ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.p at ???????/discussion/ >
