tag:blogger.com,1999:blog-9133738459621028362.post7509818305973299455..comments2012-07-08T02:10:50.371+02:00Comments on vietlh81: How to convert the K-M lens to KA lensvietlh81http://www.blogger.com/profile/15837422389135179225noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-9133738459621028362.post-34903576734810607762010-07-13T18:49:58.865+02:002010-07-13T18:49:58.865+02:00I have tried this but there is a problem.
On a K-...I have tried this but there is a problem.<br /><br />On a K-M lens the displacement of the lever is proportional to the aperture. But on a KA lens the displacement of the lever is proportional to the *square* of the aperture.<br /><br />So if you set the maximum and minimum apertures correctly with the Roberts method you will get correct exposure at f1.7 and f22. But in between these the lens is expecting a linear relationship, while the camera is assuming a squared relationship. So the aperture opens too much and the exposure is too great - it is worst in the middle of the range, around f5.6.Richardhttps://www.blogger.com/profile/11142371321636142154noreply@blogger.com