Archived posting to the Leica Users Group, 2015/09/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thanks for the feedback, George. That seems to correlate with other inputs I have gathered. Jim Nichols Tullahoma, TN USA On 9/10/2015 3:38 PM, George Lottermoser wrote: > 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 > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >