Question from my side. I get an offer for a Derogy Nr.6 brass lens.
The seller knows not really much about it and canīt give me further information.
Nr. 6 means it is for larger sizes >8x10" but which focus length does it has.
The picture he send to me shows it is a Petzval lens and not a later Aplanat lens.

Maybe it is too long for my 8x10"
I want to have a 360 - 480mm lens for portraits. A petzval will be nice.