Sinar offers no long lenses for the ArTec, max. 135mm.
Alpa has image examples of the 180 on their site
http://www.alpa.ch/index.php?tablesearch%5...ALPA_P45_08.jpg
Hi Murray
The above mentioned examples are from me, taken with the Digitar 5,6/180mm T at infinity.
Images taken with it are absolutely stunning, I use it on my P45+ with great joy, usually between f8 and f11.
Of course the usual limitations shooting with telephoto lenses apply: haze, wind and other vibrations cause problems shooting at long distance settings.
Although I sometimes use a laser distance meter (with the other lenses), it's difficult to use for the 180mm: You simply can't see the red laser dot to aim at longer distances in daylight.
It's easy to critically focus on the ground glass though, if you are familiar with 4"x5" or larger. I use the Schneider 6x aspherical loupe for great precision.
I even do some handheld shooting at infinity with 1/500sec (the shortest available shutter speed on the Copal 1), if it's impossible to set up a tripod.
Results then are mixed as expected, so I always shoot every scene several times to be able to choose the sharpest image later.
Before I bought the Digitar, I was able to compare it to the Rodenstock APO-Sironar Digital HR (which is now called the Rodenstock HR Digaron-S 5.6/180 mm): results were practically identical!
I chose the Digitar because of it's shorter available minimum distance setting.
By the way, vignetting is no problem whatsoever, even at the maximum shift of 25mm, and there's no visible distortion.
On the ALPA site, you can find technical information about every lens, including MTF, relative illumination and distortion.
The only little problem I have with the 180mm is the fact that the sync cable on the wake-up handgrip of my ALPA SWA is about 2 inches too short, so I need an extension whenever I use that particular lens.
I also use the Phase One camera, among others with the relatively new 2,8/150mm D to compare: It's is a fine lens, too. The Digitar has the edge, though.
Hope that helps
Jost