Question about Rodenstock Imagon 250mm lens

[art_major]

<p>Hello,</p>

<p>I recently bought a Rodenstock Imagon 250mm lens. I have no experience with this lens and I dont even know its complete. How many lens elements does the 250mm Imagon have? because the lens I have only as a rear element and a front hood with a diffusion disk. am I missing a front element of the lens? thanks for the help.</p>

[bob_salomon]

<p>No, it is complete. But you should also have 3 disks, a lens hood and a filter. That makes a complete Imagon.</p>

[tim_ludwig2]

<p>You can view the original brochure for the lens at butkus.org. One heck of a lens, by the way. Enjoy!</p>

[art_major]

<p>thanks.</p>

<p>does anyone know where to get the other diffusion disks? </p>

 

[art_major]

<p>what happens when you dont use any of the diffusion disks? does the lens behave like a normal lens?</p>

[q.g._de_bakker]

No. The lens is soft, all by itself.<br>The discs are sieve apertures. Stops. Not diffusion discs.<br>Without the discs, no exposure control except through shutterspeed.

[jan_h._voigt]

<p>As far as I can tell from pictures (never had one in my hands), the shutter of the Imagon is a pretty standard one, which of course has aperture blades. Used without disks, the sharpness/softness should be controllable with the aperture. Stopped down, the Imagon should be quite sharp.</p>

[bob_salomon]

<p>The Imagon actually performs as two lenses. One in the center and the other around the edge. The disks have different shaped center holes plus surrounding holes that can be opened or closed. The degree of softness is controlled by the size of the center hole and if the outer holes are open or closed.<br>

The largest center hole with all outside holes open is the softest (most halation) while the disk with the smallest hole with all holes closed is sharpest.<br>

Since the image from the Imagon is formed by the outer ens portion throwing an image over the center portion of the lens closing or opening the aperture ring on the shutter destroys the Imagon effect. To use an Imaagon properly the shutter must t=be left open, preferbly taped so that it can not accidently move from open. Er did hve spare disks but no longer have any for the 250. If we have any at all they wouldbe for the 300. The factory also no longer has any disks. The only people that might are the Rodenstock distributors. We are the one for the USA and have none but ou could contact the ones for other countries to see what they might have left. Note - distributors that factory import Rodenstock, not camera stores that sell Rodenstock.</p>

[snicker_doodle]

<p>If your shutter has an aperture I would just use that. Some will say I'm crazy but I don't care for what the holes in the discs do to specular highlights. BTW, the venerable Kodak 305mm Portrait lens uses an adjustable aperture with no discs.</p>

<p>If the shutter has no aperture but you have the largest disc then you can cut several round pieces of matte black plastic with various sized holes to slip in front of the disc you do have. You can tweak the hole sizes by metering through the GG and trimming the holes until you have fairly precise slip-in f/stops.</p>