Zeiss Distagon T* 21/2.8
Excellent! Simply excellent. Yes is true, this lens is big, heavy and expensive but the results on the field are terrific.
This lens, in the ZF.2 version that permits the control of diagphram by camera, is a manual focusing how all Zeiss lens.
The focus is extremely precise and smooth until at infinity. The great construction is in metal, also the optimum hood included.
The important dimension and weight (c.a. 600gr in ZF.2 model) can be managed very well with excellent ergonomics.
Zeiss introduced this lens in 2008 and today, in my opinion, is the best wideangle in its range (20-21mm).
On field, this Distagon 21mm, permit the closest focusing available for this kind of wideangle. This detail, for me,
is very important because this feature can allowing beautiful perspectives in macro photography. In this regard,
I've try the lens with Nikon K1 ring adapter. In this configuration you will lose all the automatisms (and, obviously,
you cannot the focusing at infinity) but you can shot some terrific macro photos with a unusual perspective.
The distorsion is really minimal both at short distances and to infinity. The vignetting isn't a real problem.
I've shooting also with Zeiss circular polarizing filter (slim) and the results are very good.
I've tried this lens on D800E and A7 digital cameras and the results are always been excellent.
But... a photo is worth a thousand words.
My opinion ( 1 Poor - 5 Excellent )
(Tested: D800E and Sony A7)
(Solidity and precision: all glass and metal)