Derogy's VR Patent Portrait-Lens, c. 1860

Derogy, Paris & London. No. 10301, height with lens hood 16.5 cm, Petzval type 3.4/25 cm, for Waterhouse stops, adjustable on the focusing wheel (two screws missing), front achromat (small spots at the outer edge indicating putty damage, insignificant in practice) and biconcave lens marked Derogy at the edge. The biconvex lens shows a chip at the edge when disassembled, which becomes almost invisible and therefore optically insignificant when reassembled with the screw ring. All screw elements move freely; the lens is clean under point light. Special feature: Identical threads on the front and rear elements allow for easy interchangeability; in the rear element, two spacer rings (5.25 mm and 1.85 mm) permit the conversion from the classic Petzval rear lens (biconvex outer lens, biconcave inner lens) to the rear lens shape of the Dallmeyer Soft Focus (biconcave outer lens, biconvex inner lens), including different distances. This is not possible with the Dallmeyer design. Whether Derogy's invention preceded Dallmeyer's or vice versa may be the subject of further research, as may patent issues. An ideal lens for experimenting with all standard and unusual Petzval combinations for creative purposes. This version is not mentioned in D'Agostini.

布雷克拍品等级是为了方便竞买人判断拍卖品的成色而设置的。布雷克等级用1到6级来标注外观和功能的成色，(从非常好到非常差)。 在目录图册里用括号里的2个数字来表示，前一个数字表示外观成色的级别，后一个数字表示功能成色的级别。如(3/2)表示外观成色是3(满意的)，功能成色2(好)。 成色 定义参照下列标准： 1 - 非常好 (未使用过，没有使用痕迹) 2 - 好 (新，极少的使用痕迹) 3 - 满意的 (普通的使用痕迹) 4 - 及格的 (明显的使用痕迹，某个非主要部件是后配的) 5 - 有缺陷的 (极明显的使用痕迹, 某个主要部件是后配的，功能上有缺陷，需要修理) 6 - 非常差 (严重破损, 缺少重要部件)