At 09:10 AM 2/24/04, you wrote:
Sorry... of course the ISO scale is a sort of geometrical progression. I've computed the half stops as for an arithmetic one :-( The worst part is that I didn't bother to check on my camera (which can set the film speed in 1/3 stops increments). So, please - next time I'll say something, don't believe me.
Alex Sarbu
----- Original Message ----- From: "John Francis" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, February 23, 2004 7:51 PM Subject: Re: Reala rated at 80
> > Alex Sarbu wrote: > > > Well... rating an ISO 100 film at ISO 80 doesn't > > means 'overexposing by 1/5 stop ... > > Correct > > > ... but by 0.4. > > Wrong. > > The right value is log2(100/80), or 0.322 (approximately) > > > ISO 50 is 1 stop, > > Correct > > > ... and ISO 75 half stop lower than ISO100. > > Incorrect. ISO 75 is about 0.4 stops lower than ISO 100. > Half a stop lower than ISO 100 is ISO (100/sqrt(2)), or roughly ISO 70 > > > > --------------------------------------------------------------- > Cauta-ti perechea pe http://dating.acasa.ro > >
--------------------------------------------------------------- Cauta-ti perechea pe http://dating.acasa.ro
I drink to make other people interesting.
-- George Jean Nathan
