AM Goerz Trigor production made by Kern?

[SimonMaddock]

Zhang and Layton,

Are/were you using the 14" in barrel or shutter? I'm very curious to know what it looks like wide open (in shutter, beyond f11), if it would be worthwhile lengthening that slot in the barrel.

[John Layton]

Copal #3 Shutter

[Hugo Zhang]

#3 shutter as well. For most of my landscape shits, I use F/32 and smaller apertures anyway.

[Drew Wiley]

Kern 14 inch Dagors were limited by the mechanical vignetting of their no. 3 shutters, and by the fact that they didn't perform as well tangentially at strong tilts as plasmat lenses of comparable focal length. I've had two different MC ones, and currently have a single-coated one. With only four air/glass interfaces plus excellent multicoating, the last version probably had the highest contrast rendering of any lens of the time - frankly, too much contrast for the color chrome work I was doing - that's why I switched it out for the previous single coat version, along with the fact I prefer the Copal 3S shutter way better than the later Compur 3. It's a fine 8X10 optic for general work; but I can't imagine using it for anything larger.

[SimonMaddock]

any focus shift stopping down from wide open?

[Hugo Zhang]

any focus shift stopping down from wide open?

Not in my experience.

[Drew Wiley]

And as per the 14 inch Kern Gold Dot Dagors, there is no focus shift from f/11 down, at very little even wider open. I got in the habit of simply setting them at f/11 to begin with, for sake of focus and composition.