Matteo Cocco Posted November 9, 2007 Share Posted November 9, 2007 i was just wondering if there is some kind of trick to consider when focusing on the lens. i mean, if my lens has focus marks for 5 feet and 7 feet, will the 6 feet mark be in the middle or slightly more towards the 7 (considering the logarithmic progression of focus)? is ther any trick to find these kind of intermediate marks? thanks for your answers Link to comment Share on other sites More sharing options...
Mitch Gross Posted November 9, 2007 Share Posted November 9, 2007 It would 2/3 of the way to wards the 7' mark. Best way to consider the log nature is to picture this: a scale from 1' to infinity. Where is two feet? Exactly in the middle. Where is four feet? Exactly halfway between 2' and infinity. And so on. Link to comment Share on other sites More sharing options...
Premium Member Chris Keth Posted November 9, 2007 Premium Member Share Posted November 9, 2007 A lot of ACs, myself included, make extra marks on the lens so we have those intermediate marks. Especially in the 5-15 foot range that is used a lot, lenses are usually lacking in precise marks. During checkout I just measure out the distance I want (like 7 feet in this case), eye focus, and add the mark with some chart tape. Link to comment Share on other sites More sharing options...
Premium Member Chris Keth Posted November 10, 2007 Premium Member Share Posted November 10, 2007 I edited too slowly: 2/3 is a good approximation, but it's not quite right on all lenses. See this photo of some master primes: The 100mm on the right shows that the 11, 12, and 13 foot markings are almost equidistant. I usually just estimate a little farther than halfway on the barrel is halfway in realspace. If you need something more accurate, a lot of ACs including myself make extra marks on the lens so we have those intermediate marks. Especially in the 5-20 foot range that is used a bunch, lenses are usually lacking in precise marks. During checkout I just measure out the distance I want (like 7 feet in this case), eye focus on a siemans star to be as precise as possible, and add the mark with some chart tape. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now