Rigid Summicron aperture question.

[robbiebedell]

<p>My 50mm Rigid Summicron aperture blades are erratic. Sometimes they open in the perfect circle as they should, and sometimes the the circle is not a circle, kind of slightly egg-shaped. Please, please do not suggest I need the dreaded 'CLA' as I know that it does. But what does an 'egg-shaped' aperture circle do on a negative? It would seem to me that any effect would be outside of the film frame. This might be a dumb question. I have not seen any effect on my negatives, but since it sometimes happens and sometimes does not, I cannot tell. Anybody out there have any experience with this? Again, please do not tell me I need a cla! </p>

[sumo_kun]

<p>Well, you don't need a CLA if you are handy. Just open it up and clean it yourself. If you are not up to it then you can either live with it or send it in to get cleaned.<br>

As for the effects, if the aperture area is the same as when it was round, then there will be very little effect on the film. Otherwise you will obviously get exposure variances depending on the severity of the problem. Another thing that can change is the bokeh if you care about hat sort of thing. You should be able to use it fine for now but in the long run it is better to get it cleaned up properly.</p>

[john_shriver]

<p>You're playing with fire not getting the CLA. The non-circular aperture indicates that there is oil on the blades, and that they are sticking to each other. If you keep using the lens this way, there's a very real chance of ruining one or more of the aperture blades (bending, or ripping the pins off the end), and Leica doesn't have them as spare parts for 40-year old lenses.<br>

Also, the fact that there is oil on the blades means that there is oil on the internal glass surfaces, and it can be causing internal haze, and causing permanent damage to the coatings and/or glass surfaces.<br>

I would recommend you invest the $100 to preserve a $600 lens.</p>

 

[robbiebedell]

<p>I guess I did not make myself clear. I am planning on getting a cla. I am just saving up for it! I was wondering what the photographic effect of the distorted aperture is...</p>

[john_shriver]

<p>Very minimal. Slight change in shape of out-of-focus disks, slightly more light getting in than the f-stop setting indicates.</p>

[robbiebedell]

<p>John, You are clairvoyant. Tonight the blades went way out of round at around F/11. I stopped turning the aperture ring and put it down before I did anything stuptid. Mind you , I have been using this lens like this for a couple of years. Tomorrow I send it to Don Goldberg. Thank you all for your input..Robbie</p>

[kelly_flanigan1]

<p>When the iris "petals" bind and stick; one gets radically higher forces on each "petal/blades" pivot. If you force it they get sheared off.</p>

<p> A lens that has seen salt spray; seashore exposure can have a tad of salt enter a lens; and those iris blades will corrode *LIKE MAD*. They are often a high carbon steel; just a hit of salt will make one blade stick to another.</p>

<p>With an older lens the iris pivots may not be available; and another lens has to be used to use its iris/pivot/blade to fix a customers lens. </p>

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