Interesting idea. Not new, and it has never worked for me. But it is worth revisiting.
Originally Posted by darkroom_rookie
Lessee, now. Copal #3 mount thread is M61x0.75, not a standard filter thread. Still won't work.
But there are other ways. According to Rodenstock's Process Lens Manual the 210/5.6 Rodagon-G's front filter thread is M67x0.75. Its rear mounting thread is M72x1. Its entrance and exit pupils are around 38 mm in diameter at full aperture. Think about hanging the lens in front of an Ilex #3 or, if you have one, a Copal #3. www.skgrimes.com or www.srb-griturn.com can turn an adapter for you.
Most of my adapters come from Grimes, I have only one from SRB. The one from SRB does what I need but is on the light and flimsy side; they designed it with threading to meet my needs, their experience with filter step rings shows. My Grimes adapters are all much sturdier.
Re y'r sketch, its good practice to make the adapter's tube that screws into the shutter as long as possible. And y'r sketch shows rather thinner adapter walls than are really safe.
In general, I prefer mounting the lens in front of the shutter to mounting the shutter in front of the lens, if the shutter will bear the lens' weight and if the lens isn't so large that it blocks access to the shutter's controls. At the moment the shortest lens I hang in front of a shutter is a 60 and the longest is a 600. My 900 has a Compound #5 in front of it. I have a couple of 210s set up to mount in front of a #1. No inexpensive step or reversing rings involved, alas.
Last edited by Dan Fromm; 10-23-2012 at 07:14 PM. Click to view previous post history.