Comments about Zeiss Zeiss Ikon 35mm f/2.0 T* ZM Biogon Lens, for Standard M-mount Range Finder Cameras, Black:

My last camera had a 35mm lens that was a poor performer, so this lens is a real treat. Check the MTF charts on the Zeiss site for the fuller story, but basically the lens is superb. I use it mostly at f2.8 and f4 where the lens really shines, with excellent out of focus rendition. It's nice to be able to go to f2 in a pinch, but that's rare for me.

The lens has essentially no distortion, making architectural photography (or any photography with straight lines near the edges of the frame) easier.

The only gripe I have is the abysmal lens cap which is an embarrassing afterthought of a design for such a nice lens. It's so frustratingly bad I don't use it at all; instead I use the combination of the lens hood and a filter, which actually works surprisingly well.

It's a great lens, which I highly recommend.

Comments about Zeiss Zeiss Ikon 35mm f/2.0 T* ZM Biogon Lens, for Standard M-mount Range Finder Cameras, Black:

I recently bought a used Leica M8 and wanted a 35mm lens for my standard lens as they are roughly normal on a 1.3 factor camera. I evaluated this lens and the Voigtlander 35mm f/1.2 Nokton and chose this lens because 1.) it was sharper from f/2 to f/4, 2.) it weighs half as much, and 3.) it's build quality was superior (specifically, the aperture ring and focus tab). If you are considering both lenses, I think that ultimately the weight and whether you really need apertures below f/2 (the Nokton is soft here) are the main factors to think about; they are both fantastic lenses.

Bottom line -- this is my favorite lens and I highly recommend it.

Sharpness

This lens is very sharp even at f/2 with improvement until around f/4. By f/2.8 it is extremely good, and even at f/2 you will be hard pressed to find fault with the sharpness unless you are doing a controlled test. A friend of mine described my photos with this lens as "scary sharp". This lens will let you see extremely fine details throughout the entire frame at f/8. I've read some reports that this lens is softer than the Nokton at f/2, but not my copies.

Color and Contrast

Zeiss lenses are famous for their contrasty look that makes colors pop, and this lens is no exception. Subjects tend to take on a 3D look due to how this lens transitions between in and out of focus. This lens has noticeably more contrast than the Nokton (of course you can tweak this when post-processing if you want more or less).

Construction, Size and Weight

This is a small, lightweight lens, though not quite as small as the Leica 35mm Type 4 Pre-ASPH. It's 1/2 the weight of the Nokton which is really huge and protrudes into the viewfinder. It is made out of metal with no plastic to be found, except for the lens cap (see Cons below). The aperture ring has a very nice resistance to it where each click represents 1/3 of a stop. You can easily select the aperture you want without looking if you count clicks. It focuses quickly and accurately; I swear I take more in focus pictures now than with my Canon 20D and autofocus lenses. The Nokton was slightly off at infinity (a common problem, apparently), but not this lens. The focus ring is nice and smooth with a focus tab (a bump on the focus ring) which lets you feel roughly where you are focusing (e.g. 6 o'clock is roughly 6 feet away). This greatly aids pre-focusing (guessing the focus before you look through the viewfinder). I don't ever want to shoot a rangefinder lens that lacks a focus tab from now on.

Bokeh

The bokeh is excellent. Out of focus lights are nearly perfectly circular. It's hard to get a lot of background blur due to the 35mm length and the short focusing distance, but given enough distance between your subject and the background you will get some very pleasing blur.

Chromatic Aberration

I haven't noticed any significant chromatic aberration with this lens. When shooting subjects outside on bright days, no purple fringes have reared their ugly heads yet.

Distortion

None -- this lens has 4x less distortion than the current Leica 35mm Summicron!

Flare

I'm not a real stickler for flare, but this lens has the best flare resistance I've ever seen. I've shot directly into the sun with a UV/IR filter and still didn't get any flare. I've only taken one picture with any flare so far which was a night shot directed at a bright light (also with filter). If you care about minimizing flare, this is the lens for you.

Cons

* The focus ring is slightly harder to turn when the camera is held vertically. In practice I haven't found this to be a problem and have taken plenty of great portrait orientation photos.

* The lens cap is pretty bad. It's made of plastic and is hard to secure properly. It does fit when the lens hood is in place, which is a plus.

* The lens hood is expensive. As a Canon shooter, I'm used to paying extra for lens hoods. I'm also used to them being plastic, which is not the case here. The lens hood is metal and vented. It works well and it looks very nice. It feels like less of a rip off than the Canon lens hoods due to its high quality construction.