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Introduction

Carl Zeiss Distagon T* 18mm f/4 ZM is one of the recent additions to the company's recent additions to the rangefiner lineup. The lens is the widest rangefinder coupled prime in the current ZM lineup - the wider angle Carl Zeiss Distagon T* 15mm f/2.8 is also the only lens in the lineup that is not rangefinder coupled. The origins of Distagon T* 18mm go back to the SLR version of the lens first released in 70s for the Rollei SL35 cameras. Interestingly, the 18mm Distagon is the only other 18mm prime besides Leica's $3,000 Super-Elmat M 18mm f/3.8  ASPH, currently manufactured for Leica M mount. I am not counting Leica's WATE here. The lens sells for ~US$1,300 new (after $200 price hike in late 20009), while used copied of the lens in good condition sell for ~US$900.

The optical construction of the lens consists of 10 elements in 8 groups. The build quality of the lens is superb as is the case with all ZM lenses currently in production. The lens is fairly compact and light, particularly when compared to its SLR variant. The lens measures 65 x 71mm, and weighing 350g. The aperture ring moves from f/4 to f/22 in 1/3 f-stop increments. The ring is located in the front of the lens and is easy to rotate by feel. The minimum focusing distance is 50cm, although M8 couples rangefinder only from ~60cm. The filter thread is 58mm, which is a very uncommon thread in the rangefinder world.

Carl Zeiss Distagon T* 18mm f/4 ZM is a traditional 35mm rangefinder lens designed for regular M systems like Zeiss Ikon and so if you are using it on a Leica M8, its effective FOV will be 24mm. The manufacturer's box includes Carl Zeiss Distagon T* 18mm f/4 ZM, shallow metal lens hood, front/rear caps, manual and warranty card. Given Leica's registry distance, the rangefinder lenses made for M system can only be used on Micro Four Thirds cameras like Olympus E-P1 in addition to the native mount rangefinders. Within the scope of this review, the lens was tested on APS-H type Leica M8.

 

Summary
Lens Composition 6 elements in 6 groups
Angular Field 98 degrees
Minimum Focus 50cm/19in
Focusing Action MF
f-stop Scale f/4-f/22, manual
Filter Size 58mm
Lens Hood Metal (included)
Weight 350g/12.3oz
Dimensions 65x71mm/2.55x2.79"
Lens Case N/A

 

Handling

First thing first. I am not a Leica-phob. Nor I am a Leica-phile either. While my first camera was actually a Russian made Leica copy, I switched to SLR systems pretty quickly. Rangefinder never cut it for me as its limitations always outweighed its benefits. Once every five years or so I'd pick up a used rangefinder with a lens or two, primarily because of my longing for something light and compact. I'd also end up selling it pretty quickly, typically right after re-confirming that the rangefinder limitations still annoy me. And so given the fact that I am not a rangefinder die-hard, you should not expect the reviews of rangefinder lenses to be any different than other reviews I've been putting up so far. If you expect to read many adjectives like 'dreamy', 'classic', 'glowing' etc. you're reading a wrong review - tune on to someone else who adores Leica just because it is Leica. With that, let's get to the actual review.

Mechanically, Carl Zeiss Distagon T* 18mm f/4 ZM has a very nice, solid, almost precision instrument like, feel to it. The lens does not balance particularly well on rangefinder bodies, as the center of weight is shifted towards the front - while by SLR standards the Distagon T* 18mm f/4 is not particularly bulky, in the rangefinder world is might be considered to be a 'larger' lens, particularly if you compare it to a lens as tiny as Voigtlander  Super Wide Heliar 15mm f/4.5. As with most UWA lenses, the focusing ring does not have much precision and rotates only for ~90 degrees. Generally speaking, this should not be much of a problem in most cases, considering that UWAs offer a much deeper DOF that most small focusing errors would be masked anyway. And if you preset the lens to f/11 or smaller aperture, your effective focusing range would cover everything from 50cm all the way to the infinity - you can pretty much forget about precision focusing at that point and use the lens as a point and shoot.

When mounted on Leica M8, the lens brings up 50/75 frame lines and so you would need to use an external viewfinder if you want to have accurate framing. Current choices include Leica's Universal Wide-Angle Viewfinder, which offers 21/24/28 frame lines for M8 (or 16/18/21 for regular film and M9 cameras), Carl Zeiss 25mm Viewfinder and Voigtlander's 25mm and 15-35mm Zoom Viewfinders. Out of these, Voigtlander's finders are the most practical in my opinion - both finders are super bright and priced right. The 25mm film finder costs US$128 new at CameraQuest and 15-35mm Zoom finder costs US$529 also at CameraQuest. Compare that to Zeiss' US$420 for its 25mm finder and Leica's US$920 for its Universal Wide-Angle finder.  Of course if you are using the lens on a M9 or traditional film body, then you'd need a matching 18mm viewfinder. Your selection is pertty much the same in this case as well. However, since EFOV of Distagon T* is 24mm, you can also try replacing the mount of the lens to bring up the 24/35 frames on M8 - there are a number of 3rd party companies offering this service, but I can't really recommend any particular service since I never used one to begin with. I ended up borrowing the Voigtlander 25mm viewfinder for my tests (24/25mm focal length is not really my cup of tea on a rangefinder and so I don't keep a dedicated film finder for anything in that range). The viewfinder worked like a charm, but gave a slightly tighter framing area then what you'd actually get with the lens. A bigger annoyance was using the external viewfinder - I really disliked the process of focusing the lens, then using external viewfinder to frame and then snapping a picture. I hated this process so much that I ended up using camera's frame selector to temporarily bring up built-in 24mm frame lines to roughly get me where I wanted and then cropping the final image if it got shifted while I took the picture.

Speaking of the framing area. Because of the size of the lens, you'd experience some blovkage of the viewfinder. Without the lens hood, the blockage is minimal - you can see the tip of the lens in the extreme right lower corner. With the hood attached, you end up with slightly larger partial blockage of the viewfinder area  - not very significant  though (less then 10%, approximately).

Assuming you are using the Distagon on a digital body like M8 or M9, you need to consider whether to code the lens so it can be recognized by the camera. The main advantage of that is the ability to rely on camera's built-in logic for applying lens specific corrections like compensating for cyan drift  (if you're using an UV-IR filter) and removing vignetting. Unfortunately, Carl Zeiss Distagon T* 18mm f/4 is not that easy to code. You can use a self-coding kit and a marker, but the markings will not hold for long and will get smudged after attaching/removing the lens a number of times. An alternative (once again, I have not tried this option and so cannot comment on its long-term benefits) is to machine the mount to create grooves that then can be permanently painted. The goal of this exercise is to make the camera think that you're using WATE at 18mm or the Super-Elmar M 18mm f/3.8.
At this point, someone not familiar with Leica M system might gasp and say 'What the @#$%$#?'. This seems like a bunch of band-aid patches applied to fix a whole slew of design kluges. And you'll be correct here - the tolerance levels of the 'rangefinder crowd' for the favorite tool far exceeds the tolerance levels of the 'SLR crowd'. An SLR system with the same number of problems as Leica M8 would have been dead on arrival so to speak. For better or worse (rhetorical statement, really), but the lack of competition in the digital rangefinder space breeds inadequacy and high prices. So what is the alternative? Don't bother with all this coding issues and use software to fix these problems in post-processing. Coded or not, the lens would still produce an image, which can be manipulated and enhanced. And fortunately, there is a dedicated software package that specifically helps you deal with M8's shortcomings called Cornerfix. I am going to skip detailed explanation on how Cornerfix works (just download and try it - it is fairly intuitive), but this is what I've been using to correct M8 files with fairly good overall results.

On the final note worth mentioning here, because the front filter thread of the lens is significantly wider then the front lens element, you can use a step down ring to attach 55mm filters, which are much more common, then a 58mm one required natively. Of course by using a smaller filter you are also risking increasing vignetting, but by how much, I can't tell, since I did not try using a 55mm filter in the first place.