Archived posting to the Leica Users Group, 2006/04/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Aram, Unless the lens is apochromatically corrected then you will have to refocus for best results. On a lens with an aperture scale, focus, then shift the focus point in the direction of infinity about two f-stop markings. That is the average of six lenses I just looked at in the focal length range of 35-50mm. For the autofocus camera, if the AF can be turned off then shift in the direction of infinity a little bit. Also, generally considered good practise is to use middle to small apertures such as F8 to F11 to cover up any focusing errors. Of course infinity remains infinity. If I remain motivated, I might use my 180 APO with some color IR film that came my way. Don don.dory@gmail.com On 4/16/06, Aram Langhans <dnaplasmid@compwrx.com> wrote: > > > I bought a few rolls of IR film for myself and a student. I will be > shooting with my R8 and he will be using his Minolta Auto Focus SLR. That > is (I think) the problem. Last time I shot IR film (25 years ago) I was > using my Rollei SL-35 and the lenses had a small red mark on focus scale > for > IR film. I focused, shifted to the red mark and shot and had good photos. > My Leica lenses do not have such a mark and I think I have read that they > are corrected well enough that I do not need to shift focus for IR. Every > other lens (NON-Autofocus) I have seen has had the IR mark on the focus > scale. Now, my student's Minolta has no mark, no manual focus scale at > all > and is autofocus. Will he be able to get well focused photos if he shoots > at a large aperture or should he stop down considerabley to achieve > sufficent DOF to have his main subject in focus? > > Aram > > This message is made of 100% recycled electrons. No new atoms were > destroyed in making it. > > Aram Langhans > Science Teacher, Naches High School > 101 W. 5th. St / P. O. Box 159 > Naches, WA 98937 > > "Science Rules" > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >