Brass Lens - Petzval Lens

From 2011, I switched my Schneider large format lenses to over hundred years old brass lenses. Now I have 6 brass lenses, they are the Petzval lenses (6in F3.6 & 8-1/4in F4.5), the Carl Zeiss Protar Serie V 80mm F18, the Wray London Wide Angle Rectilinear 6in F16, the Goerz Berlin Doppel-Anastigmat Serie III (210mm F6.8 & 300mm F7.7). I'll introduce them one by one.

Petzval Lens

The Petzval Lens was developed in 1840 by a mathematics professor of the University of Vienna, Joseph Petzval. In 19 century, the film was not discovered and people took photos with wet plate (Film had been introduced by Kodak in 1908). The ISO of wet plate was around 5 and lenses for photography with slow speed only. It was difficult to take a portrait shots due to long exposure time. 

Professor Petzval studied photographic lens which provided F3.6 and better quality at the centre of image. The faster speed reducing exposure time that made portrait shots more easier. People called the Petzval Lens as "Portrait Lens" because it was the first one specific for portrait shots and it's an ideal portrait lens.

The design of the Petzval Lens is simple as two doublet lenses with a water-slot (aperture stop) in between. It provides serious spherical aberration made very sharpness at the focus and image goes blurry behind of the focus. Beside, vignetting and spinning effect are its characteristic. The Petzval lens makes picture in good details, 3D effect and low contrast. It's pretty good for portrait and sketch photography.

My samples:

Shot by Petzval 6in F3.6

Shot by Petzval 8-1/4in F4.5