Finally I found some time to discover more details about 7artisans 12mm F2.8. I’ve been sparingly shooting with it and posted some samples from Fuji X-E2s on related Flickr public group .
I’ve recently reviewed 7artisans 12mm F2.8 on 35MMC , and during that review noticed that aperture blades are not completely opened at F2.8. Another reason for the disassembly was quite large dust particle under the rear glass in my sample.
7artisans engineers designed this 12mm ultra-wide lens without filter thread, though I see that the metal ring with letters around front glass is sitting in thread. I was not able to easy unscrew it so skipped frontal disassembly for the next time.
My lens sample has Fuji FX-Mount secured with three Torx bolts. It’s important to remember each bolt location (you’ll see later why). So gently unscrew them and store in exact order.
The Torx bolt closer to the mount lock hole has few thin aluminum shims. They simply serve to lift bolt head position, so camera locking pin will pass the bolt without catching its position. 7artisans engineers are using good amount of blue securing adhesive.
Once the mount is removed you can see that aperture ring is connected to the inner aperture mechanism through the separate (lighter gray) transmission ring. Just pull the aperture ring up to remove it. The ring can be put back in reverse order so check the aperture numbers orientation during the assembly.
You can skip unscrewing the brass pin (like it’s needed for 7artisans 35mm F1.2 disassembly), the aperture transmission ring can be easily pulled up.
The aperture transmission ring rotation is limited by the outer brass pin. However once it’s removed you can use tweezers to gently move inner brass pin that controls the aperture blades. Surprisingly it can be moved CW a little furhter!
You can see that aperture opening is now perfectly round! I’ll experiment with it in my new post to see how it affects the image. The opening area is not significantly bigger, so we can’t say it’s more than F2, so I’ll call it “F2.?” , OK? I suppose 7artisans engineers initially created the aperture module to be opened wider, but probably opening was too wide for F2.8 so the production samples are fine tuned to stop aperture opening at that point that fits F2.8.
There is quite massive (but light) aluminum ring around the rear glass. It can be simply unscrewed CCW without any tools. But be careful! Nothing is holding the glass inside to fall out, so better keep the lens facing front element down.
Here’s the final stage of this particular disassembly. It unveils access to four rear glass elements of 7artisans 12mm F2.8, that can be gently pulled out, cleaned, and inserted back (which I successfully did and cleaned the dust).
Here’s my article on 7artisans 12mm F2.8 wider aperture opening mod.