INFRARED FILM FOCUSING TEST
Independent report and analysis by Jules Alexander
This test was carried out to determine whether the IR focusing point found on most lenses (usually represented by a red dot or red line) would yield a sharper image in combination with Rollei IR400.
In this test I used the Mamiya 645 AFD, and my trusty 80mm manual focus lens. The aperture is wide open F2.8, has more than less of a flat image. Shot in full sun with a few interfering clouds, as can be slightly detected in the girl's pics. I bracketed 1/125, 1/60th, 1/30th, 1/15th. Shutter speed selected for these shots was 1/60th sec using an R72 filter. Method was to focus, screw on the filter a few threads, then shoot. All exposures were acceptable, depending on what effect the photographer wants. The shots were all ASA 25, developed in Winberley Pyro WD2D. Scanned on an Epson 4870 at 3200DPI. No sharpening whatsoever is applied in the scan or in PS afterwards, no curves or levels adjustment used, no contrast or toning applied. Negative spotting (cloning) was used for dust/hair/scratch removal on a few pics.
#1 Full frame, Visual focus
#1 Full frame, IR focus
#1 Enlarged crop, Visual focus
#1 Enlarged crop, IR focus
If the difference between IR focus and Visual focus seems a bit dramatic, it's because it is. Of course it's dependent on the lens, the aperture, and the edge of the image as opposed to the center.
#2 Full frame, Visual focus
#2 Full frame, IR focus
#2 Enlarged crop, Visual focus
#2 Enlarged crop, IR focus
I used a reflector in this one for some fill light. Clouds snuck in front of the sun as I shot giving a somewhat less contrasty image to the IR focus set of the girl's shots. As mentioned, these were all shot wide open. At a smaller aperture the focus differences are not as noticeable but of course the DOF and bokeh are affected.
The results offer clear evidence that, as is the case with all other true infrared films, IR400 will produce the sharpest results if normal IR focusing practices are used and visual focus is shifted to the IR marking on the lens.
Note: All results have been provided by independent testers. Scans and images have NOT been manipulated.