The Intricacies of Modern Camera Lens Repair (2024)

现代相机镜头维修的复杂性（2024）

Sigma 45mm f/2.8 Lens Repair & Analysis [05.12.24] 适马 45mm f/2.8 镜头维修与分析 [2024年5月12日]

I have a camera gear collection problem and as part of my personal 12 step plan, I restrict myself from purchasing functioning lenses. This sounds illogical, and it frankly is, but it’s very hard for me to resist heavily discounted lenses. To keep my hat, I tend to only bid on lenses that are less than 1/4 of the going used sale prices and have little to no mechanical damage. In this case I’ve been eyeing the recently produced sigma I-series lenses that feature mostly aluminum construction. A broken 45mm f/2.8 lens popped up on ebay in January for a song and a dance, and I simply could not resist. The auction was listed by an ebay seller that tends to have regular inventory of broken modern camera gear which is great from a repair perspective. Occasionally the seller will teardown equipment and sell parts, leaving me a bit uneasy about the internal state of the listed items for sale, but I took a chance and went with it.

我有收集相机器材的“毛病”，作为我个人“12步戒除计划”的一部分，我限制自己不去购买功能完好的镜头。这听起来很不合逻辑，坦白说确实如此，但我很难抵挡住大幅折扣镜头的诱惑。为了保住我的“饭碗”，我通常只竞拍那些价格不到二手市场价 1/4 且几乎没有机械损伤的镜头。这次，我一直盯着适马近期推出的、主要采用铝合金结构的 I 系列镜头。一月份，eBay 上出现了一枚价格极其低廉的故障 45mm f/2.8 镜头，我实在无法抗拒。该拍卖由一位 eBay 卖家发布，他经常有现代故障相机器材的库存，从维修的角度来看这非常棒。偶尔卖家会拆解设备并出售零件，这让我对所售物品的内部状态感到有些不安，但我还是决定冒险一试。

Arrival 到货

The lens came well packaged and on initial inspection, featured zero mechanical flaws. No scratches on the barrel or lens elements whatsoever. To properly inspect the outer lens elements, I use my oil free air compressor and thoroughly blow off any debris from the lens and properly clean both front and rear element with a kimwipe and lens cleaning solution. Eye glasses cleaner from the drug store is adequate for most external lenses. Isopropyl alcohol is another good alternative, but don’t use on plastic lenses.

镜头包装完好，初步检查显示没有任何机械缺陷。镜筒或镜片上没有任何划痕。为了正确检查外镜片，我使用无油空气压缩机彻底吹掉镜头上的碎屑，并用无尘纸和镜头清洁液仔细清洁前后镜片。药店买的眼镜清洁剂足以应付大多数外部镜片。异丙醇是另一种不错的选择，但不要用在塑料镜片上。

Is this broken??? 这真的坏了吗？？？

I mounted the lens to my Lumix S5 and with seemingly too much force, it clicked into place. The camera booted up fine and even displayed a live image, but no electronic controls worked whatsoever. None of the dials or switches on the lens responded to user input. The control dials on the camera did not register movement. Clearly, there was something electrically wrong with the lens. The control PCB is usually found on the rear of the lens nearest to the rear lens contact block. It would also provide a good time to investigate the very stiff lens mount.

我将镜头安装到我的 Lumix S5 上，感觉用了过大的力气才“咔哒”一声装好。相机启动正常，甚至能显示实时图像，但没有任何电子控制功能起作用。镜头上的拨盘或开关对用户输入毫无反应。相机上的控制拨盘也无法识别移动。显然，镜头在电气方面出了问题。控制电路板（PCB）通常位于镜头后部，靠近后部触点块的位置。这也是检查那个非常紧的镜头卡口的好时机。

Tools 工具

The barriers to entry on this repair are low. Most of these tools are pretty standard and generic at this point. The biggest expense besides the lens is filtered air, but even a compressed air duster can suffice. Note: Since most of the camera industry design folks are centered in Japan, the JIS screw is standard. Using a Phillips will work but it tends to wear down the heads on the JIS screws faster.

这次维修的门槛很低。大多数工具在目前看来都是非常标准和通用的。除了镜头本身，最大的开销是过滤空气，但即使是压缩空气罐也足够了。注意：由于大多数相机行业的设计人员都集中在日本，因此 JIS（日本工业标准）螺丝是标准配置。使用十字螺丝刀（Phillips）也可以，但往往会更快磨损 JIS 螺丝的头部。

• Kimwipes / lint-free lens cleaning wipes (无尘纸/无绒镜头清洁纸)
• Spray Isopropyl Alcohol (ipa) (喷雾异丙醇)
• Eye glass cleaner (眼镜清洁剂)
• Microfiber cloth (超细纤维布)
• Nitrile gloves (丁腈手套)
• Highly filtered shop air / oil free compressor (高过滤车间空气/无油压缩机)
• Tape (胶带)
• Sharpie (记号笔)
• Scalpel (手术刀)
• Plastic Spudger (塑料撬棒)
• Magnifier / optic (放大镜/光学镜)
• JIS x 2.5mm / Philips #00 screwdriver (JIS 2.5mm / 十字 #00 螺丝刀)
• JIS x 3.0mm / Philips #0 screwdriver (JIS 3.0mm / 十字 #0 螺丝刀)

Disassembly 拆解

For disassembly, I orient the lens with the aperture mark facing me and the table front edge. The rear plastic beauty spacer around the rear element is removed first along with (3) black machine screws. Following, the two nickel plated screws that fixture the side of the plastic lens block terminal interface to the metal lens mount are removed. The screws are placed on double sided tape in an orientation that matches the lens orientation. This makes future reassemble substantially easier.

拆解时，我将镜头放置在光圈标记朝向我及桌面边缘的位置。首先拆除后镜片周围的塑料装饰垫片以及 3 颗黑色机械螺丝。接着，拆除将塑料镜头块终端接口侧面固定到金属镜头卡口上的两颗镀镍螺丝。将螺丝按与镜头方向一致的方式放置在双面胶上，这会让未来的重新组装变得容易得多。

Next order of business, the lens mount bayonet and shims. The orientation and order of these shims matter so they deserve their own bit of tape. This lens had trouble mounting to a camera body so I thoroughly inspected the shims, bayonet mount back and the lens body for imperfections and surface contamination. I cleaned all surfaces with ipa and moved on.

接下来是镜头卡口和垫片。这些垫片的朝向和顺序很重要，所以它们值得拥有自己的一块胶带。这枚镜头安装到机身上时有问题，所以我仔细检查了垫片、卡口背面和镜身，看是否有缺陷或表面污染。我用异丙醇清洁了所有表面，然后继续下一步。

Note: be extra careful when handling the lens contact block flex cable. At this point in the disassembly, the lens contact block can be freely removed from the control PCB. The contact block for L-mount features 10 terminals that connect to the control PCB via a flexible polyimide cable. This flex cable has a tendency to tear easily, especially if not handled carefully. Before continuing further with the teardown, take a multimeter and check the continuity of each trace. If there are visible tears in the flex cable, repair that first before continuing to diagnose any problems.

注意：处理镜头触点块的柔性排线时要格外小心。在拆解的这个阶段，镜头触点块可以从控制 PCB 上自由拆下。L 卡口的触点块具有 10 个端子，通过柔性聚酰亚胺电缆连接到控制 PCB。这种柔性排线很容易撕裂，尤其是在处理不当时。在继续拆解之前，请用万用表检查每条线路的连通性。如果柔性排线上有明显的撕裂，请先修复它，然后再继续诊断任何问题。

The flex cable metered out to be flawless, so I proceeded the teardown. The rear CNC machined aluminum shell of the lens is up next. Two grounding straps are fixtured to the rear shell using nickel plated machine screws. The straps are oriented around the 2pm and 7pm clock position. A push-in switch flex connector is positioned around the 11pm position that can be wiggled out using a pair of tweezers. There are (4) black oxide self tapping screws that mate the shell to the center plastic lens module. The rear shell can now be safely lifted up and set aside, with the aperture mark positioned toward the table edge. The control PCB and remainder of the flex cables are now easily accessible. Three black self tapping screws mate the PCB to the plastic lens module at the 2pm, 7pm, and 10pm clock position, respectively. Once the flex cables are wiggled loose, the control PCB can be freed from the lens body and more closely scrutinized.

柔性排线经测量完好无损，所以我继续拆解。接下来是镜头后部的 CNC 加工铝壳。两根接地带使用镀镍机械螺丝固定在后壳上，位置分别在时钟的 2 点和 7 点方向。一个推入式开关柔性连接器位于 11 点方向，可以用镊子轻轻摇动取出。有 4 颗黑色氧化自攻螺丝将外壳与中心塑料镜头模块连接在一起。现在可以安全地提起后壳并放在一边，保持光圈标记朝向桌面边缘。此时，控制 PCB 和其余的柔性排线已清晰可见。三颗黑色自攻螺丝将 PCB 固定在塑料镜头模块上，分别位于 2 点、7 点和 10 点方向。一旦柔性排线松开，控制 PCB 就可以从镜身上取下，进行更仔细的检查。

PCB Analysis PCB 分析

The C-shaped PCB looks right at home with the dozens of other lens control PCBs I’ve analyzed. There’s a main microcontroller, DC-DC controller, motor controller, crystal oscillator, and a slew of passives. The reverse side is adorned with FPC (Flexible Printed Circuit) connectors, test points and an 8-pin SPI flash package directly below the main microcontroller. Inspecting any unknown PCB for faults can be quite intimidating, but I find it easiest to start with tracing the input power lines first. Where is this board supposed to receive power from? Where do the V+ and Gnd traces first begin on the PCB?

这块 C 型 PCB 看起来和我分析过的其他几十块镜头控制 PCB 如出一辙。上面有主微控制器、DC-DC 控制器、电机控制器、晶体振荡器和大量的无源元件。背面装饰着 FPC（柔性印刷电路）连接器、测试点以及位于主微控制器正下方的 8 引脚 SPI 闪存封装。检查任何未知 PCB 的故障可能会让人望而生畏，但我发现最简单的方法是先追踪输入电源线。这块板子应该从哪里接收电源？V+ 和 Gnd 线路在 PCB 上是从哪里开始的？