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Leica
Tales from the Greasy Side: Komura 105mm F3.5 Teardown.
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<blockquote data-quote="BrianS" data-source="post: 344316" data-attributes="member: 6381"><p>This thread will be continued as I try to bring this lens into working order.</p><p></p><p>For now- the teardown, as I could not find this anywhere on the web. This is a fairly uncommon lens in Leica mount. It is similar in construction to the 135mm F3.5 Komura that I relubed- and learned some lessons with. Like: DO NOT SEPARATE THE HELICAL! Too hard to get back together.</p><p></p><p>The Optical Barrel separates from the focus mount, but this one was very stubborn. A rubber sheet was required to grab the front of the lens and the aperture ring.</p><p></p><p><a href="https://flic.kr/p/QzLSoH" target="_blank">[ATTACH=full]193189[/ATTACH]Komura105_barrel_out</a> by <a href="https://www.flickr.com/photos/90768661@N02/" target="_blank">fiftyonepointsix</a>, on Flickr</p><p></p><p>The chrome trim ring unscrews from the focus ring.</p><p></p><p>The optical barrel also screws into two sections allowing access to the surfaces on each side of the aperture. The middle group will also come out of the front section, but this was not necessary for this lens.</p><p></p><p><a href="https://flic.kr/p/ScXgaS" target="_blank">[ATTACH=full]193190[/ATTACH]Komura105_focus_ring_split2</a> by <a href="https://www.flickr.com/photos/90768661@N02/" target="_blank">fiftyonepointsix</a>, on Flickr</p><p></p><p>The focus ring is in two sections, I use a silver sharpie to mark positions. Undo the set screw, unscrew the distance ring from the front section.</p><p></p><p>The front of the focus ring is held in with 3 flat-head screws. Take them out, the focus ring comes off.</p><p></p><p>Now you can extend the helical for cleaning.</p><p></p><p>This is about as far as the helical can be extended without separating it.</p><p></p><p><a href="https://flic.kr/p/QzLSmP" target="_blank">[ATTACH=full]193191[/ATTACH]Komura105_Helical_exposed_MAX</a> by <a href="https://www.flickr.com/photos/90768661@N02/" target="_blank">fiftyonepointsix</a>, on Flickr</p><p></p><p>"Do you feel lucky" in re-assembling? After my experience with the 135/3.5: I am very good at getting these back together. But not THAT lucky. I used acetone to get the old grease off using Q-Tips and paper towels. Held the helical over a pyrex dish, flood cleaned the best possible. Then used white lithium grease, focus is very smooth now.</p><p></p><p>This lens has a problem: the focus and RF do not agree, and the optics cannot be screwed far enough into the mount to correct the problem. I would have to grind the end of the helical down, and grind down the chrome trim ring. As this is a telephoto lens, I am going to use a shim on the M-Mount adapter instead. The idea is to back the RF cam out just enough for the focus to agree at ~5m. The actual focus of a 105mm lens will not be dramatically affected by a 0.2mm shift, which is about what is required to correct the RF. Will report back later.</p></blockquote><p></p>
[QUOTE="BrianS, post: 344316, member: 6381"] This thread will be continued as I try to bring this lens into working order. For now- the teardown, as I could not find this anywhere on the web. This is a fairly uncommon lens in Leica mount. It is similar in construction to the 135mm F3.5 Komura that I relubed- and learned some lessons with. Like: DO NOT SEPARATE THE HELICAL! Too hard to get back together. The Optical Barrel separates from the focus mount, but this one was very stubborn. A rubber sheet was required to grab the front of the lens and the aperture ring. [url=https://flic.kr/p/QzLSoH][ATTACH=full]193189[/ATTACH]Komura105_barrel_out[/url] by [url=https://www.flickr.com/photos/90768661@N02/]fiftyonepointsix[/url], on Flickr The chrome trim ring unscrews from the focus ring. The optical barrel also screws into two sections allowing access to the surfaces on each side of the aperture. The middle group will also come out of the front section, but this was not necessary for this lens. [url=https://flic.kr/p/ScXgaS][ATTACH=full]193190[/ATTACH]Komura105_focus_ring_split2[/url] by [url=https://www.flickr.com/photos/90768661@N02/]fiftyonepointsix[/url], on Flickr The focus ring is in two sections, I use a silver sharpie to mark positions. Undo the set screw, unscrew the distance ring from the front section. The front of the focus ring is held in with 3 flat-head screws. Take them out, the focus ring comes off. Now you can extend the helical for cleaning. This is about as far as the helical can be extended without separating it. [url=https://flic.kr/p/QzLSmP][ATTACH=full]193191[/ATTACH]Komura105_Helical_exposed_MAX[/url] by [url=https://www.flickr.com/photos/90768661@N02/]fiftyonepointsix[/url], on Flickr "Do you feel lucky" in re-assembling? After my experience with the 135/3.5: I am very good at getting these back together. But not THAT lucky. I used acetone to get the old grease off using Q-Tips and paper towels. Held the helical over a pyrex dish, flood cleaned the best possible. Then used white lithium grease, focus is very smooth now. This lens has a problem: the focus and RF do not agree, and the optics cannot be screwed far enough into the mount to correct the problem. I would have to grind the end of the helical down, and grind down the chrome trim ring. As this is a telephoto lens, I am going to use a shim on the M-Mount adapter instead. The idea is to back the RF cam out just enough for the focus to agree at ~5m. The actual focus of a 105mm lens will not be dramatically affected by a 0.2mm shift, which is about what is required to correct the RF. Will report back later. [/QUOTE]
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