Lens test...Tamron 70-125mm projection lens objective
Disassembling a Pro-Tamron 70-125mm f/2.8 zoom projection lens yielded two lens groups useful as front mounted supplemental lenses for close-up shooting. The internal "zooming" element produces very high magnification images with a very short working distance. The objective, used for this image, covers a wider field of view with a greater lens to subject distance. Here the objective was reverse mounted on a Nikon 105mm f/2.5 AI-S lens, with the camera (Nikon D40), mounted on a home-made lens testing rail adapted from a Baird Stereo Slide Bar. The stamps were mounted under glass on an articulated sliding stage allowing them to be positioned absolutely parallel with the camera back. The intent of this test was to determine the degree of "flatness of field", chromatic aberration (if any), plus evaluate lens sharpness.
With the 105mm focused at infinity, the combination gives a field width of 1.6" at a working distance of 6.75 inches. The image has received no sharpening, the only processing being a very minor adjustment to exposure and color balance. After seeing how well this element performed, I tried it mounted on the front of my anamorphic rig and it works just as well, with no vignetting that sometimes shows with "deep cell" optics fitted on my Iscorama.
DSC-2168E
Lens test...Tamron 70-125mm projection lens objective
Disassembling a Pro-Tamron 70-125mm f/2.8 zoom projection lens yielded two lens groups useful as front mounted supplemental lenses for close-up shooting. The internal "zooming" element produces very high magnification images with a very short working distance. The objective, used for this image, covers a wider field of view with a greater lens to subject distance. Here the objective was reverse mounted on a Nikon 105mm f/2.5 AI-S lens, with the camera (Nikon D40), mounted on a home-made lens testing rail adapted from a Baird Stereo Slide Bar. The stamps were mounted under glass on an articulated sliding stage allowing them to be positioned absolutely parallel with the camera back. The intent of this test was to determine the degree of "flatness of field", chromatic aberration (if any), plus evaluate lens sharpness.
With the 105mm focused at infinity, the combination gives a field width of 1.6" at a working distance of 6.75 inches. The image has received no sharpening, the only processing being a very minor adjustment to exposure and color balance. After seeing how well this element performed, I tried it mounted on the front of my anamorphic rig and it works just as well, with no vignetting that sometimes shows with "deep cell" optics fitted on my Iscorama.
DSC-2168E