yukosteel

I've used Fuji TC 2x on many adapted Nikon DSLR lens. Optically that Samyang 135mm F2 is designed for DSLR which means it has at least 30mm more space between rear glass and sensor comparing to Fuji, so TC protruding front block should definitely fit the space and work with Samyang great. The only cons is expected IQ degradation because Fuji TCs are optimized for modern formulas of Fuji tele lens, however resulting IQ may be higher comparing to image right out of Samyang cropped 1.4x or 2x times.

When I travel light single lens works best, because I don't need to think about switching lens. It happens that I miss some focal or extra aperture steps form lens left home, but that's the price of traveling light, so it's not disappointing : ) I'd choose single lens by "number of favorite shots" like MailerDaemon suggested. If you can't decide on single lens, take two and use this trip as a training for future more light trips.

Since that time I've disassembled few more XF 27mm F2.8, here is updated and extended guide of Fuji XF 27mm F2.8 disassembly. If you discover any mechanical damage, please let me know, I'll think how it can be repaired.

I still have some working electronics parts from my XF 27mm converted to manual. If you are interested I can try to look at your lens and see if AF drive replacement helps, or check if there is any mechanical damage inside which I can also fix by reusing parts I have. At least it worths trying. If it's easy fix you don't need to buy another XF 27mm, if it's non-mechanic or AF module problem (e.g. failed other component) I'll just send it back and you can list it for parts or convert to manual lens.

It may be gear problem due to use time. There are few blocking stoppers keeping focusing range and they may crack over time allowing lens to overfocus causing error. Another problem - could be electronics, common recommendation is to try to clean the lens contacts and see if it helps. Can you write more about your lens symptoms? I'll try to help discover what is wrong with it. If the lens is not repairable, then it can be reused to create manual focus mod of XF 27mm with constant F2.8. At your place I'd try to find the way to repair the lens, and if that is not possible would sell it for parts and purchase new one on eBay - there are plenty of them for about $200

I've purchased used XF 35mm F1.4 with similar symptoms you are describing. Closer inspection unveiled mechanical problem I've managed to fix - here's related article. I'd recommend to test lens focusing while camera is positioned on different angles and also check if fully extended front module is tilting to one side more than another.

XF 50-140mm F2.8 has thin metal plate with lens marking that need to be removed first, it sits on four thin adhesive tape pieces. Once removed there is a plastic ring under it that need to be unscrewed CCW. It is secured with glue in three points I can't try it on my current lens sample because it is still under warranty. Though under that plastic ring I'd expect to see bolts that are securing filter thread ring and front lens module.

From what you describe it looks that there is more damage inside than just the manual focus ring, because this lens has focus-by-wire. It means there are no mechanical interaction of focus ring and autofocus, so that ring can not physically stop autofocus. If autofocus does not work, it may be the focusing module is physically jammed (glass elements 9-11 on the picture above). It will be extremely complex disassembly process to get into the core of the lens. It may be also electronic problem, though in that case I'd expect lens to show any error to camera. I'd suggest to check first what would be Fuji repair cost as it doesn't look trivial problem to solve. If the disassembly is the only option you can consider, then I'll try to help you with steps.

It looks like plastic got cracked from the area near the stripped bolt head. Thanks for sharing useful pictures of XF 50mm F2 !

Firmware can not be downgraded on Fuji lens. Which camera do you use?

Here's article on disassembly related to your question: https://yukosteel.wordpress.com/2019/08/19/mitakon-zhongyi-35mm-f0-95-mark-ii-part-3/

Yes it is expected behavior. Aluminum-to-aluminum helicoid has a lot of grease inside. It's not something wrong, just mechanical redistribution of grease.

That is very good question. I'm sure I'd also like to use a collar for tripod especially on less durable mount cameras like X-T30/X-E3. By looking into lens shape and optical elements position I'd try following solution steps: Purchasing lens collar that can accept front area of about 63mm diameter Making or purchasing sliding tripod mount plate. Mounting lens with tripod collar positioned with leg toward the camera to the sliding mount plate. Attaching camera, and securing it on other end of the sliding plate. That should be very durable way to mount lens on a tripod for precise macro without stressing lens body and camera mount.

Can you try to switch X-T3 camera into M focusing mode, then zoom to 140mm and measure what is the minimal distance lens can be manually focused ?

Just checked XF 50-140mm F2.8 with Fuji X-T30, it can focus to 1m distance on all focal range up to 140mm.