Church -- NEX-5N & Canon FD 35mm f2.0. Click for larger.
Today is sort of a perfect day for photographs -- overcast sky after a light misty rain and the greens are very green and colours seem to jump out at you. I was eager to try out the FD 35mm f2 that I bought from the camera show yesterday.
It turns out that the warming effect was from the yellowing of the glass elements. This version of the lens is "radioactive", because the glass contains thorium. This is similar to the famous yellowing on many old Takumar 50mm f1.4 lenses. The solution is to expose the elements to UV light. For me, it really does not matter, as one of the advantage of shooting RAW is that you can adjust white balance afterwards. I actually like slightly warmer colours.
The lens is very sharp, which is the consensus of most of its users. There are six or seven versions of this lens and later design has a different optical formula with a convex front lens surface, whereas the older design has a convcave front element (my EF 180mm f3.5 Macro also has a concave front element). Regardless design, all versions are very good lenses.
So far, the only aspect of the lens I don't like, is the bokeh. The lens itself has an 8-bladed aperture, which I thought should give better looking bokeh, but to me, the bokeh just looks weird.
Bokeh -- NEX-5N & FD 35mm f2. Click for larger.