Wollensak’s Velostigmat Series II is a Tessar formula lens introduced about 1909. Series II Velostigmats had an aperture of f/4.5, and came in barrel mounts, Studio, Regno, Autex, Optimo, Betax, and perhaps other shutters. The Series II was Wollensak’s most popular lens, recommended for portrait, group, landscape, and “general use”. It came in quite a few focal lengths, from 3.5 inches through 19.5 inches. The 9.5, 12, 15.6, and 19.5 all had an optional diffusion adjustment that is fairly common, and some of the shorter lenses were occasionally featured it, (I’ve seen a 5 inch model with the diffusion feature, and own an 8.5 inch with the diffusion option).
The Velostigmat Series II lenses were manufactured until just after WWII, with the later models being single coated (Wolcoated) by the factory. They were renamed the Raptar Series II and put into Alphax shutters in the late 1940’s, and production continued through at least 1957, though the adjustable diffusion option was discontinued by the time these lenses were coated.
The adjustable diffusion is one of the more interesting features of the Velostigmat Series II, and one that sets it apart from the many other Tessar lenses available. (Note: Ilex's Series A Paragon f/4.5 was a close copy of the Velostigmat Series II, and some of those had the diffusion feature as an option.) The adjustment was a rotating front ring that allowed the front element to be unscrewed one rotation, giving it slightly more distance from the other elements. The first mention of the diffusion ring I've seen is in Wollensak's Feb. 1, 1911 price list, but it may have been available earlier.
There is some confusion as to how it should be used, but the 1916 Wollensak Lenses and Shutters Catalog explains:
“The amount of diffusion is variable at will and so places in the hands of anyone artistically inclined, a powerful means of expressing their individuality. It is by no means difficult to manipulate this attachment, by turning the front mount around to the marks 1, 2, 3, 4, or 5, as desired, then focus. When the indicator is set at 0, the lens is ready for general work, producing negatives with snap and life; set at 1, you have a slight diffusion, at 2, a greater degree of diffusion, and so on, the higher the number, the greater the diffusion.” (The rotation causes the focal length to shorten slightly, so the focus-then-set-the-diffusion method results in an out-of-focus rather than soft-focus image.)
In actual use, very little diffusion is evident, even at setting 5. This has led some to try focusing at the 0 (sharp) setting, then dialing in the softness. But the Wollensak catalog makes it clear, set the diffusion, then focus. So what is the “artistically inclined” photographer to do?
There is a “cheat” possible that allows one to adjust the diffusion far past the factory limited setting of 5, to a setting that would be (by counting the rotations, 5 to a full turn) of 40 or so. At that setting, the Velostigmat Series II has an obvious and (at least in my eyes) lovely soft-focus signature.
This modification to the lens involves removing one of two restraining screws inside the lens that restrict the rotation to a single revolution. I documented the process on my 15.5 inch Velostigmat Series II to show the procedure:
1.) Here’s the lens. The front element is to the left, and the seam just behind the front edge of the barrel is the giveaway that this lens has the diffusion adjustment.
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2.) First you need to unscrew the front “beauty ring”, the ring that's engraved with all the lens info and threaded in through the filter threads to hold the front element in. If your lucky, you can do it with the friction of your thumbs. If you can’t budge it and you’re desperate enough, you could drill two small holes on opposite sides of the beauty ring and force it with a spanner wrench. If the front rim is dented, forget trying to thread the ring out. Your best bet is to have someone with very strong hands force the rotation until one of the little screws shears off. I got lucky; mine unscrewed with my thumbs!
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3.) Remove the ring
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4.) Under the ring along the rim you’ll see a little screw. This bumps into another little screw down below it.
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(to be continued...)
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Originally Posted by Mark Sawyer
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