Cooke Series II -Anastigmat lens-205mm.f4.5-13x18cm

I've acquired this lens yesterday, and perhaps someone can help with the meaning of the indication that is near the f22 aperture engraving: "EXT 324 mm". There is two aperture marks, at max aperture one is at 4.5 obviously, and the other at 8. I suppose this triplet is not a convertible. This lens as far I could discover was optimized for portraits and in the lens rear element is written in french to unscrew it 3 turns to make it sharper.

I've made several searches in different forum archives , at the article once published by View camera magazine and in Cooke's website , but nothing specific about this particular lens was found. Any more details about this lens would be appreciated . Thank you all.

You have an unusual lens. I believe the "EXT" marking indicates an extension lens which Cooke supplied as an accessory item to increase the focal length. The catalogs I have, however, state that they were not made for the Series II.

The Series II was made as a general purpose lens of large aperture. The variable diffusion provision was available on the larger sizes. This is a nice feature, since it permits some control over softness independent of aperture choice. Cooke changed the mechanical arrangement of the control several times.

There is a lady who works for Cooke who has responded to questions about their lenses on the f32 LF forum at www.f32.net. She may be able to help.