R.O.J.A Vorm Emil Bausch Rathenow lens

[Geoffrey_1456]

Hi I was asked about a large format collectible lens, but I don't know the answ er. I believe someone from this forum can help us out. It's a R.O.J.A Vorm Emi l Bausch Rathenow Rapid Aplanat #2 Series D F8 brass barrel lens. The lens is a bout 50 mm tall, front diameter about 40 mm and rear 35 mm. F stops labelled as 8, 12, 16, 20,...., 360. Does anyone know about its construction (elements in groups), coverage, focal length, and sharpness? Thanks in advance.

[Dave Willison]

I don't have an exact answer but I'll take an educated guess and wait for someone to correct it!

I believe the lens is a german lens manufactured by Rathenower Optische Institute (ROJA) under the direction of Emil Busch. According to Kingslake, aplanat is an old term for a lens corrected for spherical abberation. The aplanat was originally designed by Steinheil and is similar in design to Dallmeyer's Rapid Rectilinear. The lens has four elements cemented in two groups with an aperture in the middle. The lens is symmetrical with the front and rear elements being identical. The term rapid apparently comes from the fact that the lens has a maximum aperture of f8, which was faster than earlier distortionless lenses. According to Kingslake, the RR lens was introduced about 1866 and "fitted to all the better cameras for nearly sixty years."

I don't know which Rapid Aplanat you are describing or its focal length. Wooden's Large Format Reference Manual lists three rapid aplanats: 7 3/4" (5x7), 10" (8x10), and 13 1/2" (8x10). All three rapid aplanats are listed as f8. Wooden's book also lists four series D aplanats: 150mm/f6.5 (4x5), 165mm/f6.5 (4x5), 170mm/f7 (4x5) and 200mm/f7 (5x7). I would put the lens on a camera, focus at infinity, and measure the approximate focal length by the distance from the film plane to the lensboard.

I hope this helps.

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[Geoffrey_1456]

Thanks, Dave! The lens was sent to me by UPS ground, and I'll test it next week.