What does a paraxial digital camera mean? How about reverse documentary ratio?

Paraxial digital camera is a digital camera with the light path next to the light path when framing.

Paraxial camera is an ancient technology. Because what you see when looking at the camera is different from what you see when imaging, there is a certain parallax, that is, what you see is what you get, so it was replaced by the later SLR in the field of professional cameras.

In other words, from the big direction, the paraxial digital camera belongs to amateur machine, and the SLR belongs to professional machine.

As for the imaging effect you mentioned, because of the machine positioning problem of paraxial digital camera, the photosensitive elements and lenses directly related to the imaging quality are incomparable to SLR. Of course, the price is not the same. As you said, Leica's D-LUX4 is only a few thousand yuan, and even the limited edition of Military Green is only about 15 thousand, which is an order of magnitude worse than the price of Leica SLR of more than 2 million.

However, due to the German origin of Leica camera, the imaging quality of its lens is extremely excellent, which is unmatched by Japanese cameras. Personally, I think the imaging quality of Leica's D-LUX4 can surpass some entry-level SLR kits!

This camera of yours is worth collecting.