Bronica S 105mm repair

[jim_peterson2]

<p>I was very happy to find a fairly clean copy of this lens in the junk bin yesterday but when I got home I discovered the problem. The focus ring goes from MFD to about 5 meters and then binds and won't go any further. Where it stops it doesn't hit a hard stop with a clack like at the normal end of the range. It just suddenly gets tight and stops. <br /><br />So I want to take this lens apart and see what's going on but don't know where to begin. The lens butt has about 7 or 8 tiny screws so I'm a bit intimidated, not knowing which ones to loosen. Should I start from the front? <br /><br />Does anyone have experience disassembling this or similar lenses? How complicated is the focusing mechanism? Are there certain things I need to mark or note during dis-assembly in order to get it back together properly? And most importantly, does anyone have any convincing theories on what may be causing the problem?<br /><br />Any help or advice appreciated!</p>

[kparratt]

<p>You may find something helpful <strong><a href="http://www.butkus.org/chinon/bronica/bronica_s/bronica_s.htm">here. </a></strong></p>

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[jim_peterson2]

<p>Thanks Kevin. Unfortunately I don't think Butkus has anything with specific lens instructions. </p>

[jim_peterson2]

<p>OK, time for an update. First the good news; the lens works perfectly now. Now the embarrassing part; it always worked perfectly! The problem? It disappeared when I removed the rear lens cap! The rear-most edge of the rear group was hitting the rear lens cap, preventing it from going to infinity. But why? Well, just a minor detail... I was using an ETR rear lens cap. When I found the lens at the store in the junk section it had no caps. So I went to the crates full of caps and started to hunt. I couldn't find an SQ rear cap but found an ETR one and tried it out. And it fits just fine! I thought, lucky me! Only now have I discovered that the SQ cap is deeper. And the most embarrassing part: I had the lens almost fully disassembled before discovering the source of my problem. I removed the front ring and front element (rear cap still in place) and when I checked the focus ring it still wouldn't go to infinity. Then I removed the rear cap, the rear element and the rear plate and discovered that the focus ring worked fine. So I figured something had been jammed. Reattached the rear plate, re-inserted the rear element and it still worked fine. Now before reinserting the front element I attached the rear cap, flipped it over and started to insert the front element. Tested the focus ring and "oh no! the problem is back!" "Must be related to the front element"... Anyway this foolishness went on for some time until the light finally clicked on in this cloudy brain of mine! "I can see clearly now..." :)</p>

[ondebanks]

<p>Good story Jim - you live and learn. The lens surgery may have been unnecessary, but now you've learnt something about the interior workings of this lens - which might come in useful in the future.</p>