Zeiss Sonnar 180/2.8 Iris Not Operating

<p>I acquired a "zebra" version 180/2.8 Sonnar with adapter for use on Exakta cameras. The iris seems to have become disconnected from the control ring because it remains wide open no matter what I do. There are two "mechanisms", or "switches" (don't know what to call them) protruding from each side of the lens just behind the aperture ring. Please enlighten me as to their purpose. I believe that the one on the right side may be a stopping down device for a depth of field preview. It moves freely, springs back into a default position, and seems to be have some connection to the pin that's supposed to activate the iris from the rear of the lens. I cannot seem to budge the one on the left. I don't know which way its supposed to move, what it is for, or if it is related to the inoperative iris. I've seen some comments about problematic iris' on these lenses but nothing specific as to the exact nature of the problem. Am I doing something wrong? It appears that the iris mechanism is easily accessible from the rear of the lens. is this an easy fix?</p>

<p>It's not disconnected, the blades are stuck with oil. The little silver button on the right is indeed the DOF preview, but with the blades stuck open it doesn't do anything. Not sure what you've got on the left, mine doesn't have anything on that side (but mine is Pentacon Six mount, that might be the difference).</p>

<p>What you need to do (or have done) is to open up the lens (from the front) and clean the oil off of the aperture blades. I have some sketches of this operation that are not perfect but may be helpful. Please email me at <a href="mailto:rick_oleson@yahoo.com">rick_oleson@yahoo.com</a> if you'd like a copy.</p>

<p>I would add, that this is the most common problem with this otherwise spectacular lens.<br /> I got mine stuck up and had it cleaned by a local repair person, but now it is stuck open again, so I am requesting Rick's instructions myself.</p>

<p>The good news is that the flaw sometimes allows you to buy one that isn't working on the cheap.</p>

<p>Whenever the lens is not mounted on the camera, always store it with the aperture set to the small end of the scale - f/32, 22 or 16. This will keep the blades out in the air, rather than all stacked together where the oil can get between them. This will allow you to increase the amount of time between having to go in and clean it out. You don't have this option when the lens is on the camera, so don't store the camera for long periods with this lens on it - put the 180 on the shelf and mount the 80mm (or better yet, a body cap) on the camera.</p>

<p>Marco, the "switch" to the left of the Sonnar gives you the option of turning the ring with the tripod thread on it. Pushing it up loosens the ring, down fixes it. Congratulations, by the way, that you got one of these great Sonnars 2.8/180. Couple of months ago, out of curiosity, I took a few shots to compare it to the 2.8/180 Nikkor ED, the 2.8/180 Elmarit (first version), and the Minolta AF 2.8/200, aperture fully open. Very unscientific, but the result was clear: they are all in the same league, I couldn't put my finger on any definite difference in any category. Sure, the Sonnar is much heavier and bulky, too, but it's a medium format lens and a vintage lens design. Enjoy!</p>