Petzval Portrait Lens, c. 1864

Unsigned but almost certainly by Darlot, brass-bound, height with sunshade 21 cm, glass of the front lens Ø 80.6 mm, focal length approx. 3/32 cm, the edge of the rear element originally labeled "Darlot", with several other heavily abraded inscriptions, with Waterhouse stop Ø 7.5 mm (approx. aperture 32), all elements can be screwed on, for a screw-on of 102 mm, glass clean under point light. - Note: The front part of the retaining ring originally had after one 1 cm distance a lens speed reducing size of Ø 68 mm, creating an effective aperture of 1:4.7 instead of 1:3. - Excellent user lens, in good condition.

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)