Archived posting to the Leica Users Group, 2015/09/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Sep 10, 2015, at 12:29 PM, Jim Nichols wrote: > Thanks, Ken. I located a step-up ring and filter at B&H that will work. > My lens does not have an infrared focus index. Do you have such, or, if > not, how did you decide how to focus? Just by what you see through the > filter? > > Your images certainly appear to be well focused! My understanding of focusing invisible spectra requires a manual shifting of focus once you "know" the visible light focus distance. Further each lens, IR filter, and film/sensor combination will determine a "different" focus shift. On my 40 mm Summicron with B+W 090 IR Filter on M8 Sensor This translates to moving the focus ring from dead on to the third mark to the right (between 4 and 8) This seems to give me accurate focus, even wide open, at 3 Feet (.9 Meters) Regards, George Lottermoser http://www.imagist.com http://www.imagist.com/blog http://www.linkedin.com/in/imagist