Quote Originally Posted by Thomas Wilson View Post
Is that not what you are essentially doing here? (in photo)
I can state with almost certainty that no self respecting engineer would design a collar for an enlarging lens. Your assembly can not be correct.

Does your cone mount from the narrow end or the wide end?
Every cone-lens extender I have used mounted to the enlarger at the wide end and the lens mounted to the cone at the narrow end (rear element towards the negative). It was an efficient way of putting some distance between the lens and negative without over-extending the bellows.

I think your cone is designed to mount a lens in the neighborhood of 360mm, minimizing bellows draw.

The wide flange of your cone probably fits the same slot as your three lens turret. Use one or the other?
Apparently I was wrong, except the part about a self respecting engineer....
From your picture, it would appear that you have one hell of a nice enlarger, albeit one designed with 5"x7" negatives in mind, not 6x6.

My advice would be to remove the 80mm lens, bend some 12 gauge copper wire in a forked loop that bends out of the way of the light path, slip the forks into the grooves on the aperture ring, and then tape the hell out of it. Then remount the lens.

Good luck.