Changing Linhof "Ground glass"

[Bill_1856]

Having the Fresnel in front of the GG is NOT a strange setup. That's the arrangement used on hundreds of thousands of Speed and Crown Graphics. The reason is simple: The Fresnel (actually a Kodak product called an Ektalite Field Lens) is relatively soft plastic, and placing it behind the GG would expose it to the trauma of focusing loupes and other evil instruments and dirty fingers. It is the same problem that requires Beatie and Maxwell screens to have a thin piece of clear glass behind them for protection.

[Juergen Sattler]

Well, I did go out today and shot some Polaroids with my Technika III and the focus is spot on and the groundglass is bright with a 90mm lens. I guess the Fresnel setup for the III really was meant to be the reverse of what I am used to.

Juergen

[Steve Tharnstrom]

Thanks for all your responses.

I believe the gg/fresnel/shims are as originally installed, though the shims are a bit warped. The gg, without fresnel/shims, is at the film plane, give or take a few hundred microns (1/15,000", or so). Thanks, Bob, for pointing out a fresnel is occasionally installed on the lens side of the gg, like on a IV.

I'm either missing something, or the day I shot the distant subject conditions were more breezy/hazy than I thought. Maybe I'll try a few through the window w/ camera on concrete tripod, ship camera in for a check-up and adjustment, or shoot a smaller, less sail-like format on only clear calm days.

Thanks again.

Steve