The BFL9000: optics or plumbing?
I'm not sure if I should be proud or embarrassed about this MacGyvered beast of a lens. The central component was taken from an old 8 mm movie camera which I recently picked up at a yard sale for $3. In its original life, the lens was 7.5 - 60 mm f/ 1.7 and projected a tiny image circle onto 8 mm movie film. I have no idea of the specific internal configuration of this lens except that it seems to function as a strong negative lens with a variable focal length. I added two more negative elements in front of it, and two positive elements behind it to get a combination that produces a large enough image circle and will reach focus from infinity down to objects in contact with the front element. The resulting focal length is approximately 40 mm. The off-axis aberrations are interesting.
The BFL9000: optics or plumbing?
I'm not sure if I should be proud or embarrassed about this MacGyvered beast of a lens. The central component was taken from an old 8 mm movie camera which I recently picked up at a yard sale for $3. In its original life, the lens was 7.5 - 60 mm f/ 1.7 and projected a tiny image circle onto 8 mm movie film. I have no idea of the specific internal configuration of this lens except that it seems to function as a strong negative lens with a variable focal length. I added two more negative elements in front of it, and two positive elements behind it to get a combination that produces a large enough image circle and will reach focus from infinity down to objects in contact with the front element. The resulting focal length is approximately 40 mm. The off-axis aberrations are interesting.