![]() Supplemental Markings: Some Wollensak shutters have a date penciled or scratched onto the rear diaphragm ring, which is visible upon removing the rear lens cell.For example, a serial number first appearing in an October 1947 issue of Popular Photography would be assigned to that same year, but a serial number first appearing in a February 1946 issue would be assigned to 1945. This study tracked the appearance of specific lens serial numbers and assumed that the actual production date was at least three months prior to a particular serial number’s first appearance in a publication. Advertisements and Catalogs: Beginning in the 1940’s, Wollensak advertisements and product catalogs began to regularly feature photographs of lenses with visible serial numbers.A lens with a name ring in plain, all caps font with a serial number slightly higher than a stylized lens’ serial number can likely be associated with 1937. A 14” Series II Velostigmat with pre-stylized font on the name ring can therefore be assigned to 1922, the year the lens debuted. For example, Wollensak appears to have used the stylized “Triangular O” font on lens name rings from 1923-1936. Appearance: Even when product lines remained static over years, changes in product appearance help to further constrain production dates.Eras with frequent, well-documented product changes are the best characterized. By identifying and overlaying dozens of such narrow production ranges, serial numbers fell into a reasonable and orderly sequence. A 15.5” Velostigmat Series II with a serial number higher than a series IV Velostigmat can be therefore be associated with 1920 or 1921. As another example, the Velostigmat Series IV was introduced in 1920, and the 11×14 Series II Velostigmat focal length changed from 15.5” to 16” in 1922. A lens with the highest serial number observed in a “bulb” Studio can likely be associated with 1915, while the lowest number in a “wire” Studio can be similarly associated with 1916. For example, Wollensak’s Studio Shutters included a pneumatic bulb attachment from 1906-1915, and a wire (cable) release attachment from 1916 onward. Availability: Referencing the Compendium, this study constrained production dates on the serial numbers of specific products.Methodology: This project associated serial numbers with production years by evaluating thousands of Wollensak lens images, advertisements, and documents for changes in product availability, appearance, and any supplemental markings. Notes on methodology, caveats, and specific lens series information are found below the table. These posited numbers are a best estimate with a potentially wider margin for error. Other serial numbers below are posited to bridge the gaps between bold numbers, with product appearance and availability consistent with the year indicated. ![]() Using the table: Serial numbers in bold below are better characterized and assessed to have been produced in the year indicated, with an error range of plus or minus one year. Lastly, the Optar lenses Wollensak made for Graflex were originally included in the Anastigmat Series, but later branched into a separate series. In addition, Wollensak applied separate numbering series to select non-anastigmatic lenses: the Petzval-design Vitax and Vesta, the soft focus Verito, the Series IIIa Extreme Wide Angle, and the Varium and Beach portrait lenses. The Anastigmat Series includes Velostigmats, Raptars, and essentially all Wollensak lenses with serial numbers except those specifically noted below. Wollensak initially applied this main numbering sequence only to their highly corrected lenses, so it is designated as the “Anastigmat Series” (AS) in the table below. One main numbering series appears to span the length of Wollensak’s lens production. If you have information to correct or improve the table below, please drop me a line. It is a work in progress, to be updated and improved as additional data comes to light. ![]() The theory advanced below is based on detailed study of Wollensak products, trade literature, advertisements, and limited original technical documents. In the absence of definitive Wollensak production documents, any approach is a theory. This page offers an approach to make sense of the serial numbers on Wollensak lenses, and to correlate serial numbers with production dates. ![]()
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