Archived posting to the Leica Users Group, 2011/11/04
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Doesn't anyone read their Gossen exposure meter manual anymore? The Lunalux, Lunalite, Lunasix F, LunaPro F manuals all include the following explanatory text (along with other, much more useful material): "The [meter] is calibrated in 1/3 f/stop increments with numerical indications at full stops. A table is included below with the actual numerical values of the 1/3 stop increments listed for levels from f/0.7 to f/128. Values not listed can be calculated from the formula that follows: New f/stop = (old f/stop) (square root (2) to the power (f/stop change)) For example, if you wish to stop down 1/4 stop from f/4, take the square root which equals 1.414 and raise it to the power .25 which is the decimal equivalent of 1/4 stop." The table is in the appendix, and reads as follows: .7 2.8 11 45 .8 3.2 13 51 .9 3.5 14 57 1 4 16 64 1.1 4.5 18 72 1.3 5 20 81 1.4 5.6 22 90 1.6 6.3 25 101 1.8 7 29 113 2 8 32 128 2.2 9 36 2.5 10 40 To make sense of that table, you will of course need to have a non-proportional font. Doesn't anyone read their emails in plain text anymore? Piers -----Original Message----- From: lug-bounces+piers.hemy=gmail.com at leica-users.org [mailto:lug-bounces+piers.hemy=gmail.com at leica-users.org] On Behalf Of George Lottermoser Sent: 03 November 2011 18:31 To: Leica Users Group Subject: Re: [Leica] 1.8 vs. 1.4!?!? On Nov 2, 2011, at 5:32 PM, Mark Rabiner wrote: > I looked up f 1.8 vs. 1.4 thinking it was between a half and a quarter > of a stop and they are saying its 2/3rds!?!?! Anybody know that that's true? > > Where is there a photo calculator that tells you these things?!?!? I always thought the basic math for 1 f stop revolved around a factor of 1.4. 1.4 x 1.4 = 1.96 1.8 / 1.4 = 1.29 so - yes - 2/3 would seem close enough for. what? I'm not sure. Regards, George Lottermoser george at imagist.com http://www.imagist.com http://www.imagist.com/blog http://www.linkedin.com/in/imagist _______________________________________________ Leica Users Group. See http://leica-users.org/mailman/listinfo/lug for more information