Yes, it will be an ordinary right hand thread, I have removed that part from a Flektogon myself. I'm also assuming this is a regular thread as I see no need for it to be reversed. I've tried acetone and lighter fluid in an attempt to free the ring, but to no avail. It's the top ring in the photo, immediately above the thread. Yes, the back ring is the one that will not budge. I speak from much experience with them! That said, I always managed to get them right in the end. The way they often come apart, if you've not dealt with one before, you may not always be aware you really ought to have noted and marked the relationship of certain parts, until after you've split them, and lost the orientation. You need to be careful stripping the focus of these old Zeiss lenses. Or is this what you're trying to unscrew, without success? It's unclear. What are you having trouble with, exactly? You'll have the room needed if you remove the back ring, first. Maybe using some acetone drops could help to unstack it. There is no way to get inside and remove a retaining ring (if it is there). The image in my post shows the lens almost at the closest distance. The Biotar comes very close, but when the Flektogon is set to close focus there is almost no gap between the outer body and the inner assembly. The construction of this lens is different than both of those in the videos. Thanks for your suggestions, but I'm afraid I'm still no further ahead. Giorgio Battera edited this topic 14 months ago. When you turn the focus ring to the minimum distance, on the back of the lens you will see a retaining ring, removing it, you will separate the optical block from the helicoid. Hi, it could be similar to the Biotar 58mm silver:į/disassemble-czj-biotar-58mm-f2-f22-coo. Perhaps this could give you some ideas: Good luck!

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