[Leica] IMGs: Finding the “right lens/film/sensor/camera” combination:

[George Lottermoser]

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 

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