Optically though, Contax Zeiss has some blisteringly good zooms. Our DP this weekend, Joe Victorine, texted me this after using my Contax 28-85 on the Ferry:
He then addedI just jizzed my pants over your Contax. I want!!!
When he came back to set, he checked the wave forms of the shots, and when compared to his Leica R's, the low-con Contax look was giving him about an extra stop on latitude, which he loved.Contrast and sharpness are insane. But still somehow soft.
Optically, Contax has some great zooms. Here's a great starting point:
CONTAX 28-85 3.3-F4
--> This to me is the most USABLE Contax Zoom. It's very large, and very heavy, has great range, and has fantastic all manual focusing. The focus rotation is massive, easily btw 270 and 360 degrees. It's the lens Joe is talking about in his texts above. Zeiss in their literature on this lens state that they were trying to make this zoom essentially a variable prime, as the MTF ratings clearly show this lens being WICKED SHARP. At 28mm, it close focuses even better than the 28mm 2.8 prime.
This lens is FANTASTIC.
CONTAX 35-70 3.4
--> This is arguably Contax's most famous zoom. It's become something of a cult classic, because it's even more conservative and high performing than the 28-85. It's become quite popular with travel photographers, as stopped down it delivers massive resoltion for landscapes. Also, the MACRO function is between a 3:1 and 2:1 and is incredibly useful. The IQ on this lens is pretty insane. It's getting very, very hard to find, so get it now because in a year...it will be gone.
Also, the constant 3.4 aperture is very useful.
That being said, I still find the 28-85 more versatile for shooting.
CONTAX 80-200 F4
--> This lens is insanely cheap. You can get a perfectly clean one for $300. I'd argue it's one of the best $300 you'll ever spend on a lens or any piece of gear. It's not INSANELY sharp, the MTF charts place it just below the other zooms listed above, but the LOOK and IQ are through the roof. I use this lens ALL THE TIME. The focus rotation is like like the 28-85, from 270 to 360 degrees. Also it has a great Marco 4:1 function when you are at 200mm. Paired with the 28-85, this zoom is KILLER.
CONTAX 100-300 4.5-5.6
This is a very famous zoom. I've seen it referred to as "the 35-70 on steroids". Essentially, this zoom has MTF ratings that BLOW primes out of the water. It's quite slow, but the sharpness and IQ are supposed to be mind boggling. People like to pair it up with the 35-70 for a great one two punch. I've only used this zoom once, and I think it needed to be serviced, so I can't speak first hand about this one. But it's reputation precedes it. Priced usually way over $1000, if you can find one affordably, run don't walk to get it.
CONTAX N 17-35 2.8
WARNING!!! This is a Contax N lens. From Zeiss's very short lived AUTOFOCUS line. This zoom though is supposed to be AMAZING. It's frequently compared to the superb Nikon 17-35. The CONTAX N mount is extremely hard to adapt to ANYTHING. However, CONURUS in Vancouver (for $500) can completely replace the mount and make it EOS. If you find this lens affordably, I'd give it a shot.
Hope this helps!!!