schattenundlicht Posted August 13, 2017 Author Share #21 Posted August 13, 2017 (edited) Advertisement (gone after registration) I was trying a similar exercise with my Leitz UTOOV mid to dark red filter for my 85mm Summarex, where you can see from the table I published above that a factor of 15 is suggested. My SL meter said -4 EV, which is a huge discrepancy. Either the tables are rubbish or modern TTL metering is under estimating the effect of a filter. Odd! Wilson The Leica Table gives "filter factors" which are related to exposure as follows: Filter factor = 2 <raised to the power of> X Thus X = log<base >2 (FF). A filter factor of 15 ~ 2x2x2x2 = 16 would give 4 f-stops (leaving out some decimals) which is exactly what you metered! [unfortunately the forum software does not allow for correct mathematical notation.] Kind regards Mathias Edit: I just looked it up in a logarithm table; please increase exposure by 3.9068905956 f-stops :-)) Edited August 13, 2017 by schattenundlicht 1 Quote Link to post Share on other sites More sharing options...
Advertisement Posted August 13, 2017 Posted August 13, 2017 Hi schattenundlicht, Take a look here FIGRO. I'm sure you'll find what you were looking for!
wlaidlaw Posted August 13, 2017 Share #22 Posted August 13, 2017 Edit: I just looked it up in a logarithm table; please increase exposure by 3.9068905956 f-stops :-)) ......well approximately anyway Wilson 1 Quote Link to post Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.