[Nikon F] I was hesitant in purchasing this lens because I have become comfortable with Leica, Zeiss, and Voigtlander as my three manufacturers of choice for my M240. At the time of purchase, my wide options were the VM 12mm f/5.6 III and 21mm f/4. Here are some observations from tripod-based testing when comparing to the 12mm VM.

1) The Laowa is more contrasty than the VM at f/5.6.
2) The VM seems a bit sharper across the frame when approximating an equal frame, not enough for me to consider this a major factor. For example, I didn’t notice a difference until at 200% zoom in my ~10 comparison shots.
3) The Laowa is noticeably brighter per f stop. This could be due to a number of factors that I don’t have the equipment to test but I would say the Laowa is around 1/3 stop brighter at f/5.6 compared to the VM at f/5.6.
4) The Laowa rendered noticeably warmer than the VM
5) The Laowa has a tactile stop at 0.7 meters that I personally appreciated.
6) Build-wise, the Laowa seems to have very narrow tolerances. It feels like my 50 Planar ZM in build quality and smoothness of focusing.
7) The filter compatibility is a nice touch that I plan to test in the future. That said, the same option is available for the 15mm f/4.5 VM III.
8) The Laowa has noticeable vignetting wide open.
9) The whole zero distortion thing isn’t just marketing. While I was only taking test shots around the house, I think I’ll appreciated this when traveling.

In sum, I’m going to give this little guy a shot. The 12 VM is on to its next owner. I’m still on the fence as to whether to keep my 21mm VM but it will at least stay in the cabinet for a few months to see if I can live without it. I’m still fixated on the idea of having one lens wider than my 28 Biogon and don’t want the bulk of the Tri-Elmar (or the hole in my wallet). It will take some time to see if the Laowa’s focusing stays smooth and the build quality holds up. I’ll try to update my review or post a new review down the road with some images.

[9] If you are not looking for perfection at this price, but a special way of rendering the world, you have a winner with this lens.
I take any chance to slow down and to become more creative.

[13.53 lb] Perfect lens, wide and free of spherical distortion.

[Full-Frame] Excited to have these for macro photography, but buyers should know at least mine arrived dark grey rather than black.

[Fixed Focus] Best

[50x] SO GOOD

[Fixed Focus] This is fun lens, super-wide and it performs quite well. Not a lens to be used for Milky Way shooting, but great for landscapes or normal night photography, including star trails. Coma is fairly well controlled with its smallest f/5.6 aperture. If you are comfortable using fully manual lenses, this is a nice addition, very compact in the bag!

[Fixed Focus] I USE MY SPOTTING SCOPE FROM MY FRONT/REAR DECK TO LOOK AT VANCOUVER BC..ALSO THE BOATS IN SAN JUAN HARBOR.VERY EASY TO USE ,,GREEEEEAAT OPTICS.SO CLEAR AND CRISPY CLEAN....I LOVE IT!!!!!

[Fixed Focus] Vignetting, corner softness wide open, and some distortion are noticeable. But when you factor in the size and weight of this thing, it's an engineering marvel that such a lens is possible, and at such an affordable price. I own the Samyang 10mm f/3.5 XP and that lens has a very annoying green cast in the corners, and I am delighted that this lens suffer way less, and much easier to fix in Lightroom or CameraRAW. However, stopping down the lens doesn't improve vignetting, unlike the Samyang.
Strangely, the mid-frame some how isn't as sharp as the extreme corners when you focus using the center. I suspect that the plane of focus isn't a plane not a sphere. It could be mustached, but further investigation is required.
This lens works well with the Techart LM-EA9, and can get you very close to your subject as long as you are not blocking all the light. It's a shame that the TTartisan adapter would not correctly read the code of this lens as the Leica 6-bit code cannot represent9mm f/5.6 at all. Let's see what happens in the future.
Despite its many non-idealities, I am still inclined to give it a 5/5 for being a pioneer in ultra wide angle non-fisheye.

[Full-Frame] Requires very precise positioning of camera, subject and lighting to get the best out of it.