The following rendering and focus tests involve the Leica M8 camera set at ISO 160, mounted to a Leica Table Top Tripod, and with a 40 mm Summicron lens: 1) without a filter; 2) without a filter converted to black and white; 3) with a B+W F-Pro 092 Infrared Filter; 4) with a B+W F-Pro 093 Infrared Filter.
A cable release was used to engage the shutter. The lens is set between f:2 and f:2.8 for all samples. The rangefinder is focused on the top edge of the vase; just above the ceramic medallion. The 40 mm Summicron has depth of field indicator marks on the lens barrel at f:2.8, f:4, f:5.6 and f:8. After focusing with filters on: an exposure was made after moving the indicated distance one line to the right (closer); then the next; etc. In each case the white balance dropper was placed on the lower right corner of the light switch.
The results: We can observe the infamous “magenta” Infrared Light effect in the unfiltered photograph. And the “average” black and white rendering when converted to B&W. We then observe the distinctive IR effect with the 092 filter. And as expected the focus moves out away from the original full spectrum focus (from the front of the vase to the light switch). We discovered that the 092 filter requires moving the focus to at least the f:2.8 mark; probably a tad more. This test also confirms my original tests (a few weeks ago) that the 093 filter requires a move to the f:4 mark. I also found it quite interesting just how differently the two filters DO render the subjects. Also as expected the IR filtered images do exhibit a slightly “softer edge.” And I believe that the 093 is ever so slightly softer than the 092; which may make sense insofar as it’s cutting at a higher frequency.
Oh. And by the way… the 092 allows 4 stops less light to reach the meter/sensor… the 093 allows more than 6 stops less light.
(click photograph for larger view)
1) First exposure: no filter.
2) Same as above though converted to black and white.
3a) With B+W F-Pro 092 filter. Rangefinder focused as if unfiltered.
3b) With B+W F-Pro 092 filter. Rangefinder focus moved right to f:2.8 mark.
3c) With B+W F-Pro 092 filter. Rangefinder focus moved right to f:4 mark.
3d) With B+W F-Pro 092 filter. Rangefinder focus moved right to f:5.6 mark.
3e) With B+W F-Pro 092 filter. Rangefinder focus moved to f:8 mark.
4a) With B+W F-Pro 093 filter. Rangefinder focused as if unfiltered.
4b) With B+W F-Pro 093 filter. Rangefinder focus moved right to f:2.8 mark.
4c) With B+W F-Pro 093 filter. Rangefinder focus moved right to f:4 mark.
4d) With B+W F-Pro 093 filter. Rangefinder focus moved right to f:5.6 mark.
