Blair Tourograph & Dry Plate Co. (Boston, MA)

Single Achromatic Lens Variation 1 (inserted stops), c.1880-c.1885


 

Photographic Apparatus, Blair Tourograph & Dry Plate Co. (Boston, MA), 1884, p.19


 


Notes: 

Every large camera company offered its version of the straight barrel single achromat.  Blair probably purchased theirs from Darlot or an equivalent optical company, then engraved their designations on the barrel.

Blair Single Achromat Variation 1 had stops that are insertable from the front and held in place by a wire spring clip.  The glass (a cemented doublet) is at the rear of the barrel and is full diameter.  Since it is not corrected for off-axis aberration, it is only used with small stops; the lens therefore has a rather small fixed stop; smaller stops can be inserted from the front.

Blair Single Achromat Variation 2 replaces the loose stops with stops on a rotating wheel.  By 1890, the only camera that came with the single achromat was the Lucidograph, and, accordingly, the lens was called The Lucidograph Lens.  

References:
Photographic Apparatus, Blair Tourograph & Dry Plate Co. (Boston, MA), 1884, p.19

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