Upload & Sell: Off
Apologies in advance for the length of this post...
I've used Canon L glass for the last 20 or so years. A couple years ago I made my first foray from Canon and picked up a used M9 and added a few Zeiss ZM lenses: 21/2.8, 35/2.8, 50/2. I've never used Zeiss's ZE/ZF glass, so don't really know how the ZM lenses compare to those. When I figured I liked the M9 and would stick with it, I started adding some Leica lenses: 21/1.4, 28/2, 50/1.4 ASPH, 90/2.5. BTW, my decision to try the M9 was because I wanted a compact system with high quality lenses, particularly wide angles, which was where I felt Canon was most lacking. I considered getting some ZE lenses, but the size of some of those, and the fact my DSLR kit was already quite heavy, turned me off. So for me, it wasn't about buying a Leica because it was a Leica, but rather, because it was about the only solution that fit my criteria at the time.
Leica glass compared to Zeiss: I would agree with Jim's earlier comment that images with Leica glass seem to be a bit calmer and more relaxed in some respects. The lenses have really good sharpness, but especially wide open, are not brutally sharp. There is a slight smoothness to the sharpness. With the 50 Lux ASPH, at closer distances, there is certainly a trace of some spherical aberration. Since this is about the distance for a nice head and shoulder portrait, I don't consider it a negative. At the same time, global contrast is still quite strong with rich colours, yet not overboard. With the 50 Lux ASPH in particular, the background bokeh is very neutral, without any outlining/rings in out of focus specular light sources, but still has some 'character' to the way it renders scenes. I guess it's pretty sterile compared to some vintage glass, but it's also not completely neutral.
When I only had the Zeiss ZM glass, and maybe it was also because I was new to Lightroom and went a bit overboard learning it, but I found that the contrast/pop of many of those images really made me want to push the contrast and clarity even more. With Leica glass I find there is a softer subtlety to the images, particularly if shot wide open, that is lost by applying clarity, particularly to background rendering because clarity boosts the contrast in those areas to a degree unrepresentative of the lens's character (if that makes sense).
After some time now with the Leica lenses, I find I shoot them generally either wide open, or stopped down a lot for depth of field and to clean up any quirks. For example the 21 Lux has fairly poor calmness to the sharpness character in the image mid zone area at moderate apertures, especially when focused towards infinity. So here, if I can, I'll shoot it at f/8 or 11. In such applications the 21/3.4 should certainly be better at wider apertures. But at close distances, and at wide open, especially with some physical subject/background separation, the 21 Lux has a really nice character. Again, good but not blazingly hard sharpness with a bit of subtle "glowyness." And for a lens this fast, it surprisingly retains really good contrast in wide open backlit situations (though does purple fringe like crazy - thankfully LR4 makes this a one-click fix).
Objectively comparing Leica to Canon is for me more difficult because I'm shooting all my Leica glass on a Leica camera and Canon on Canon. It's difficult to know how much of each system's file characteristics are integral to the way each manufacturer has optimized those qualities for each of their cameras. But I suspect each is optimized to be similar to their results on film. Going back to certain L lenses on film, such as the 200/1.8, I thought Canon's look at the time was high sharpness but lower global contrast for a more subtle, pastel-like look. Compared to that lens, I thought the newer 135/2 had a lot more punch and was somewhat uncharacteristic of the line, at the time. But now with my newer Canon glass, they all seem to have somewhat higher global contrast. But there is still a pretty big difference in look to Canon files vs. Leica files. I would say a bit flatter, lower global contrast. More gray haziness that needs a good tone curve to boost contrast and saturation, along with some clarity to get the image to pop. Back when I used Photoshop a lot more, I would run images through various USM scripts with low amount and high radius passes to boost global contrast. The Leica files definitely have richer blacks and shadow characteristics. I shoot my Canon gear and the M9 side by side on jobs, and it's necessary for me to process each with significantly different settings to get them to a similar final look - generally with more aggressive settings for the Canon files. Is this a bad thing? From a post production and prepress environment (a field I also work in), not necessarily, because the Canon files contain all the info, just need a bit more 'beating' to get to the desired end result. But it also means the need for more operator experience to know how to get there, and also I believe, results in a fair amount more personal interpretation during post production.
As for colour characteristics, I'm not sure how much this is the programming in the camera vs. the lenses, but with the M9 I definitely find I'm always toning down yellow/green, especially for anything with foliage. Often it could be as much as -20 to -30 points of green saturation, especially in the spring, otherwise everything looks dayglo radioactive.
The new M will be interesting in a couple respects. I hope to eventually get one and it will theoretically mean I'll be able to use my Canon lenses on it, so would be interesting to do some side by side comparisons to see just how much of a difference there is between the two. Additionally, whether all the talk about the new CMOS sensor and how it maybe won't look like the CCD-based files of the past Leica digital cameras, will actually be the case. The Leica reps here seem to like to say it won't be an issue and that CMOS won't restrict the way they optimize the sensor to the look they want to deliver.
As for samples... I don't have any SOOC cat photos to show but have one PP'd 21 Lux image I'm pretty happy with of my cousin's dog. The PP for this was basically exposing for the background and bringing up the foreground about 2 stops in LR, and pulling back the green saturation a bit and tweaking the yellow and orange hue characteristics. It was shot at f/1.4 and I really like the separation I see, yet the background is still fairly defined.
I posted these recently on the M8/M9 thread - a quick ambient light portrait set, shot in order, on the 50 Lux ASPH, 28 Cron, 21 Lux. All wide open, all with fairly similar and minimal PP treatment:
I posted these images awhile ago in another thread, but thought they might be of interest here to show differences in OOF foreground/background rendering. Various normalish fast M mount lenses on the GXR:
The order shown above: 50 Lux ASPH, CV50 f/1.5, ZM50 Planar, CV40 f/1.4
WB based on the ZM image, brightness adjusted to match the white in the C of Canon. Of the various LR parameters, contrast was set to zero, black point at 5, clarity at zero.
Here are some Canon 50L f/1.2 images on APS-H sensors... the last one has had a fair amount of PP/retouching to the subject, but not the background rendering.