Okay, so this seems to be something to look into, but you gotta admit it seems almost impossible that Yuneec could make such a bone-headed mistake but if its possible okay lets figure it out. Curious, do you have access to a micrometer? I would like to rule out either Freewell or Yuneec as being the ones changing the size of the thread mount. If we can get measurements we will see which is which.
And please know I am just asking, so don't take this wrong but, you are positive that there is nothing on the the lens body of your C23 and it looks like mine in the picture above in that; it is showing the threads and they are slightly smaller in diameter than the body of the lens housing?
Also where are you located?
Hello Ty.
I feel I need to clarify something here.
As we know the C23 is the E90
I have both cameras and I have the freewell filters and they do for me fit both cameras. So we are both very lucky.
Whilst you are correct Freewell filters should fit both E90 and C23.
However the problem actually started on the E90 many many months ago.
Yuneec are shipping different size threads and on the smaller thread the free wells keep spinning and do not tighten up.
I borrowed an E90 from yuneec for a while the free wells did not fit.
Kev Waite also has this issue on his E90.
So I measured the thread size and on some E90’s the thread was 0.5 mm smaller.
So to get around this problem I wrapped PTFE plumber tape around the thread this then made the freewells fit.
But here is the weird thing.
Using the uv filter that comes with the E90 I swapped them both around and each fitted on the other E90. Go figure that out.
But the freewells didn’t.
Anyway it seems that yuneec may of had a certain number of threads manufactured wrongly.
Hope this helps the OP out by using plumbers tape to make them fit.